A MASTER MECHANIC/ RESTORER taught me; WHEN PROPERLY TUNED, TIMING SET & CARB SET PROPERLY ITS: 1 2 3 relatively quick pumps to floor & wait 10-15 seconds for fuel to atomize and turn to vapor. Then turn key and it fires everytime and idles smooth and clean!! IT WORKS!!
I like your tunnel ram demo. It explains my hair loss when I was 24. I was helping a buddy with a hesitation problem on his tunnel ram in a '65 Chev pickup. I was watching under the hood when he hit the gas. It lean back fired and this huge fireball came out from under the hood and burned the hair off the top of my head... My hair never came back... HAHAHA
tony I am an old gezzer, my fist attempt at racing was a Pontiac 261 6. I made a 3 signal manifold, it did basically the same thing, the first couple laps it was a dog, so I a made a heating device for /under the manifold and plumed heater water to it and back , it worked great
I have been trying to balance this low temp boiling point problem with street driven carburetors for many years. I demonstrated this once for a customer who brought me a small block Chevy/Nova combo. It was properly and neatly installed, all new and the tune was reasonably close. He had a steady power loss as the temp came up but no overheating, max 195f. I cooled the engine with a larger radiator down to a steady 170deg f. Helped a little but after several miles on a warm/hot day he still started losing power. I plugged the exhaust crossover in the intake and fabricated a heat shield with insulator gasket under the Edelbrock carb, helped more. I demonstrated the gas boiling in the carb by running the Edelbrock carb with the top off, manually keeping the fuel bowls filled. Did this from a cold start to full temp. As the carb bowls reached around 150 deg f you could see the fuel start to boil. It, the fuel, looked really hot boiling. When I stuck my finger in the boiling fuel in the bowl and held it there it demonstrated that it wasn't as hot as it looked.
Australia 1970 , Chrysler Australia used the mighty Valiant VG 4 door Pacer as their race cars , the standard 245 CI HEMI 6 was taken out to 251 CI and a 4 BBL Carter carb fitted , these cars went HARD ! kept up with the Ford and GM V8's on the long tracks and beat them on Australia's short tacks because of a 3 speed manual gearbox just using 2nd and 3rd . But ,, as you say Uncle Tony they had no end of trouble with the 4BBL flooding when fitted the standard V8 way ,, it had big top end power but bogged and with a 3 speed was slow at start and out of the corners . So what they did was exactly what you have done here and turned the 4BBL 90 degrees and it fixed that major problem , they became very competitive , then in 1971 the VG was superceded by the mighty VH 2 door Charger with 265 CI and triple Webbers and 280hp on the E38 3 speed and 320hp on the 4 speed E49 ,, Australia's fastest accelerating production car until 2002 when Ford made the 6 cylinder 'Barra' Turbo 6 , Falcon BA . So from 1971 to 2002 they were the fastest ,, good history . FYI , the 4BBL Pacer was named so , not because the had a 4 barrel carb , 4BBL stood for ' Four Big Bad Litre's ' Love Plan Z and look forward to Saturday , Thanks Uncle Tony .
P.S. I'm 78 years old so that theory has been around for a long, long time. All us Motor / Gearheads love your show. Been a MOPAR man since 1962, when I first got interested in speed and noise. Only new car I've ever owned was a 1964 Plymouth. Thank you very much for that idea ( RICHARD PETTY )❗👍🇺🇸🇺🇸🇺🇸🇺🇸🇺🇸✌
I remember people doing that, saying it improved performance. But they were wrong. Or confused. Modern Dyno testing has proven that there's no HP gains from using a cool can. It's cold air that allows for better combustion. Cold air with hot, well atomized fuel is the golden ticket. 👍 😉 I've read something about cooling the return fuel/air mixture that didn't burn though. But I believe that's for a fuel injected setup with a return system and all that stuff. 🤔
often that was a percolation issue as the mechanical fuel filter soaked up engine heat as the closed hood would trap heat in the summer. Roadkill once made the mistake of putting their Hemi Bee's fuel cell in the trunk of the super bee...no air flow..and they showed the fuel just bubbling away. so they spent $100 or more filling the trunk with bags of ice in 100 degree desert driving. as for performance, here's Richard Holdener's view th-cam.com/video/ymFjK3PRL_A/w-d-xo.html
The Clifford intake has a water box built into it. When I first installed that intake on my slant, I didn't hook it up because I didn't have any extra heater hose. I barely made it around the block. Next day, hooked it into the cooling system and I've been driving without a problem since.
I run all my engines at 160 Fahrenheit 70 Celsus. Dyno tests have shown this temp to make the most Horsetorques. So what you are saying makes total sense to me.
Fabricate an aluminum plate and bolt it to the bottom of your intake. Drill and tap two 1/2" pipe thread holes in the plate. Screw in two heater hose fittings. Attach a heater hose to each pipe fitting. You now have a heated intake manifold. So very simple and easy to do. Install a shut off valve on one hose to limit heat buildup. I made one for my old Plymouth flathead six and the drivability increased by 50%. You got this!
You could make a small heat exchanger out of copper pipe and stick it to the bottom of the intake and circulate coolant through it. Use a heater valve to regulate the flow so you can get the temp you want.
Had two darts as a teen and both had slant sixes. The stock configuration had the exhaust manifold attached to the intake (And both cars would vapor lock on summer days). This configuration was the norm going back to the inline 4's, 6's and inline 8's of the 20 -30's. On Chevy v8's I would restrict both heat runners with a piece of stainless sheet metal with a 1/4 inch hole in each because the Holly carb would warp the throttle plate and cause air leaks. Another important thing with engine temp is making sure your oil gets to 215~220 to cook off any moisture that can accumulate in the crankcase from the PCV system sucking humid air in.
After several attempts with wraps and oil line cooling hoses we came up with either an oil cooler or a heater core for under the manifold. Installed a temp probe at the plenum to maintain temp at 150 to 165 degrees F. It was definitely a street killer of V8's. Just some thoughts.
I believe that as soon as you stomp the gas after the intake reaches 150 degrees, the intake charge (atmosphere) will suck most of that heat away, I have a homemade aluminum intake that even in the summer would develop a layer of frost/ice between the carb and the head, I wrapped the runner with the oil cooler hose and improved driveability enormously
I'd say it's highly likely you're correct, might finally get the manifold to heat soak and it just cools itself again. Luckily it's a drag car so he only really needs the one warm hit
The gasoline vaporization requires energy as the gasoline molecules such energy out of the aluminum it will cool Key is to have sufficient mass or weight such that temp drop is within acceptable range Interesting experiment would be to get manifold up to 150 at idle then monitor temperature under plenum as you pinch the throttle
@@ccpgmike620 I can assure you that as soon as the gas/air mixture hits the hot aluminum intake it (the intake) will lose heat like there's no tomorrow
@@davebaker9128 I agree! I did a very rough calculation: vaporizing 1 fluid ounce of gasoline can instantaneously drop a 20 pound aluminum manifold ~3 degrees F. Knowing specifics of fuel consumption and wieght of the slant manifold, Uncle Tony can ratio this estimate. BTW ethanol takes like twice as much energy to vaporize as crude oil based gasoline
Tony - I'd take the temperatures you were reading off that bare aluminum sheet with a BIG grain of salt - IR thermometers measure radiated infrared, and are typically calibrated for an emissivity (how readily a surface emits IR) of 0.95. Materials like that aluminum normally have an emissivity closer to half of that or less, and as a result will read lower than their actual temperature. To test it, try painting a part of the surface of your aluminum plate flat black, then heat it again and repeat your measurement with the IR gun, pointing it at both the painted area and the plain area right next to it. My bet is that the black area will "appear" a lot hotter to the thermometer, thought both are actually the same temp. Just something to be aware of with IR thermometers, and something that's much more obvious with IR cameras that show an image - shiny metal will often look cold relative to more emissive things nearby. When measuring components on a circuit board that have metal cans, I usually put a piece of blue painter's tape on them to get a more accurate reading. The painted parts of the engine are likely much closer to reading their true temp, though still might show a bit cooler than they truly are. The header should be pretty much spot on.
Yes, even running cars look like the cold sky through my FLIR scope, only the tires, tail pipe, and halo under the car look hot, even when the sheet metal feels much warmer than ambient. Predator vision is a very strange world. I can see footprints with it for about a minute, but a paper target on a wood stand is completely invisible. "Paint" the target pattern with some water or spit in dry air and you can see it from over 100 yds.
Painting the Al plate mat black is a good suggestion (the emissivity of the plack paint will be higher than 0.95, the standard setting of non adjustable IR temp guns). However uncle T's red shiny manifold is next up for guestimation of it's emissivity. Perhaps he would like to remove the red and spray it also mat black. The black paint will also help with the inlet manifold taking in more of the heat radiation of the exhaust manifold.
If you are correct ,put gas on the aluminum plate then record the reading when the gas starts to boil. That reading will be your reference number to use when recording the time it takes the cold engine to start boiling gas in the intake
Back when I was a smog mechanic. I learned that a carburetor at 100° outside temperature would run at 32°/freezing, that's why guys at the out in the desert with their sand buggies added really huge Jets to make it not stumble, what they didn't know it was ice crystals forming inside the carburetor. Thanks for remind me of something I forgot. Keep up the good work I like the way you teach these new kids.
Assuming those sand rails were running VW engines, I know exactly what you are talking about. Guys will put a big center mount carb but will not try and make any provision for heating the intake manifold. So then they were jetting rich for the stumble. With dual carbs and short intake manifolds all that goes away. But sand rails are used, well in the sand and desert. Having a carb hanging out on the side of your engine makes it quite vulnerable to rocks and dust. The center mount carb is for practicality. But it creates it’s own problems without intake heat.
Yes, that's why aircraft gas engines have carb heaters to prevent icing as incoming air at altitude cools as it accelerates into the throat of the carb.
@@joehoeing6590 , I'm aware of carburetor icing but this is a race car that doesn't get driven in winter and surely doesn't fly at high altitudes (hopefully). I still fault the design of the intake manifold and I also question the logic of that orientation of the carburetor since all air/fuel from the primaries is directed towards the front 3 cylinders and the rear 3 will be lean until the secondaries open. And if this is a vacuum secondary carb there is a chance that the secondaries will open late or possibly not at all.
Not knocking the carb, but I now see why port injection is more controllable and preferred in modern engines when it comes to fuel efficiency and energy production. The injector is atomizing cold fuel right on the hot bits.
Garage 54 in Russia made a perspex intake manifold for a Lada, the result was interesting and probably shows what you are talking about at cold manifold temps. worth the 20 mins or so to watch
I’ve always wondered why small planes have Carb heat and was told it’s for icing. While I know that’s partly true, I’m sure this also helps vaporization.
Just for fun, I looked up C16: boiling begins at 193 and the upper end of vapor range [90%] is 226 degrees. That puts a midpoint around 209 degrees. Vaporization is done [no liquid remains] at 351 degrees. Jenkins was near a walking encyclopedia of all things combustion engine.
My wrenching mostly occurs in the context of my 1951 pickup with a slightly later 235 “Stovebolt” inline 6. This is a familiar issue to those with Stovebolts. The factory 216/235 setup works really well for a driver. It’s a heat flap on the exhaust manifold that warms the intake under the carb. A bimetallic spring opens/ closes to regulate it. One of the challenges for those who run aftermarket aluminum intakes or especially headers, is having a way to heat the intake absent the factory setup. Some intakes have provisions for a tube that supplies coolant or exhaust via copper lines. Some have rigged up their own setups. Lots and lots of disparate opinions on how well the aftermarket setups work, if at all. For your application…a drag only car, I suspect your idea of a long warm up is the most logical place to start. One concern: since you’re running with no charging system, will the battery voltage drop enough during the warmup to create ignition system weirdness?
After watching the entire video, I can suggest to get the engine temp to normal operating temp. If I can recall, the thermostat in those engines were 180/190 deg. I'm old, so I may be off on the thermostat. But it would help the engine efficiently to warm it up before you run it.
I had a 1980 LeBaron that the previous owner put large piece of aluminum under the carb. And a shroud under the exhaust to the intake. 30 pluse years being a mechanic, was wondering what they were thinking. Now I know why my slant 6 ran so good. You figured it out. Sad part is somebody beat you to it. Love your channel. Keep it up.
You gotta understand Uncle Tony some people are just here to criticize you they don't need to look at the video and see what really happened or what you put on the car when you build it they just look for any reason to complain But if you don't have ignorant haters you're doing something wrong
I agree with @ homotorsports . Will the higher air fuel mixture flow during burnouts cool off the plenum more than it can reheat before you make your run. You should test it before the weekend so you don't waste the trip to find out it doesn't reheat and it does the same as your other runs and bogs.
And a water line. Gonna hook one or both back on tomorrow now that I have my carb sorted. Couldn't tune out a mid speed detonation. Brand new power valve wasn't opening. Now I can get the intake heat working again.
You're on to something here. I had a 39 year career as a Chief Engineer in a power plant and during that time I worked along with quite a few combustion engineers. We wouldn't have used air pre-heaters, on power boilers, ahead of burner windboxes if hot air didn't speed combustion. There is a lot going on in an engine intake manifold. A cool dense air mixture is a good thing going in but once the fuel enters the plenum it should pick up enough heat to give a kick (you call flash) to the fuel mixture to get efficient combustion so there is no stumble or bog coming off the line. I'd be careful adding auxiliary heat. You're probably better with an extended warm up time if you can make due with that. Fred
Tony, a simple and low-cost mod is to install a temp sender to measure the manifold temp. not the air temp! the temp of the metal of your manifold. Your pick of a coolant or oil temp sensor, then use a toggle switch to display it on a suitable OEM gauge! FWIW use a toggle switch with enough poles to include the switching needed for indicator lamps..
I wonder if you drilled and tapped the intake to take a temp sensor, let the sensor butt up against the casting, so it reads the casting temp then add a temp gauge for it. It may not read the exact temp but I'm sure you could likely figure out a delta using a gauge and the temp gun. That could make for some fun and easy data collecting and testing.
Tony I went through this year's ago. The direct connection manual is wrong. If you turn the carburetor sideways, all your plugs will burn clean everybody that follow follows the direct connection manual, has to run plugs of varying ranges As proof, the same manual shows you how to weld a 2 barrel Plat on, rember? And they welded it sideways for racing. I daily drove one for years, tried every way just to be sure. Hollies, carters, even factory thermoquad and even GM quadrajet? Many would suffice, but the best I found was the one off my cross ram Hemi. Also mounted sideways...
Why not make a plate that bolts up like the stock exhaust manifold and run engine coolant through the plate? You could run a 160 thermostat and hopefully get your 150 under the carb. I used to be in the Ford 300 scene and that’s what we did. Your correct on how the carb needs to be facing. The 300’s would do the same thing without heat. With no heat my 300 was not drivable at outside temps under 55 degrees F. I love the Slant content btw
You are over thinking hot rodding the slant six with that POS intake. You need a 883 close ratio four speed 4:56 gears ,13 to 1 compression , big solid flat tappet cam , high rpm and light weight fiberglass body parts to make that manifold work with a four barrel carburetor for racing. Put a Gear vendors on it if you want to drive it.
Wicked good vid Uncle Tony! I love how you break it all down in easy ways to understand. Can't wait to see the vid of Plan Z's next pass! Cheers from Maine!
Well, since you brought up how the tunnel ram works, I'd get a custom tunnel ram made for a slant six that lifts and centers the carb.....problem solved????? Besides-how cool would that be :)
It is interesting to note that not a single slant 6 racer heats the intake and none of them is having your problems. Maybe you you should reach out the "rusters" owner and ask his advise.
Use a heated coolant from the heater feed ports to a heat a block bolted to the bottom of the intake. You could use a heater control valve to regulate temperature.
G'day, I recon a heat riser pipe, bolted to underside of manifold, extending down to exhaust. 4-6 inch dia. or multiplesmaller pipes. If it's too hot, drill holes in it. If not hot enough, add more pipes. Anyway, good luck with it.
Balancing the heat is tricky. Hot air expands, takes up more space in the runner. Same with fuel. I think it was Smokey that said you wanted it as cold as possible from the outside air, to the plenum, just shy of allowing carb icing, then you wanted it to stay cold to about the point where the intake transitions into the head but not so cold that water vapor would build ice in the runner. From that point forward, you wanted as much heat as you could get, just to the point that the fuel would vaporize around 15-20% of the wet fuel. That mixture allowed the front end vapors to ignite better and create the heat you needed to get closer to optimizing the burn while still maximizing the amount of mixture you can get crammed into the cylinder. In Vizards book, he talks about coating intake valves and getting more HP, but his engine was more of a road racing build than a drag build. It would make sense that you would gain in a long distance engine that spends more time at full power but I think the drag racing engine would benefit less except at the top end of the track. You're needing starting line vaporization. Looks like you are on the right track. Maybe narrow up the valve seat widths on the intakes to allow less heat transfer and give a sharper edge to shear the fuel next time you have the head off.
Interesting video, how about building a tunnel ram for the slant. Simple exhaust tubing and a box for a plenum up through hood. Would be a cool experiment.
I have seen so many tuning problems that just come down from a cold intake manifold. Many always blame the carb. End up with an over jetted mess that still doesnt run well. Uncle Tony clearly shows that in this video. Like he said, i also grew up around blocked off intake heat for power. But on a hot street car, that can be a real PITA... I used to get on this forum that mostly talked on Ford 240/300 inline six truck engines. The first thing most guys did was put exhaust headers on, a open plenum 4 barrel intake. Then try and live with it as a daily driver. I tried to help many on there with their tuning issues, some figured it out. Adding a coolant plate under the intake plenum to warm it, is a good bandaid fix. On my truck set up the same way, but no tube headers. I made my own split cast iron exhaust manifolds, that retained the factory heat riser bolted the the intake manifold. My 390 Holley 4 barrel works perfect, with the jets that came in it... Any inline six engine suffers from too cold of an intake, because it hangs away from the engine heat, unlike a V8. That is any inline six modified like this... Uncle Tony, i believe you will have to bite the bullet, and add some form of heat to your Slant six intake, ( more than you want). Just to get the car to launch well, even if it costs you some top end power... Love your videos !
Great experiment! I have heard of the water passage heater blocks for those manifolds. Never had an issue with my cast iron (keyword cast iron) manifold.
You're on the right track, but lest we forget the cooling effect of the velocitized incoming charge of air and fuel combined with the surface temp of the warmed manifold, a further reduction/loss of temp will be seen inside the plenum. I say on the right track because more heat soak of the plenum will be needed to achieve your theoretical latent vapor process. Keep truckin!
I always enjoy your content Uncle Tony. It seems you broke from your normal way of optimization of the existing systems. The engineer may have had more than fuel economy in mind when they made the exhaust manifold bolt to that section of the intake, possibly they ran into the same issue you are fighting during the R&D. Keep up the good work on Plan Z!
I love how you're experimenting. Very cool. As far as testing vaporization on the aluminum plate, I'd suggesting making a plate about the size of the carburator baseplate in the form of a dish. That alum. plate you used probably has a big temp gradient making it inaccurate. The google says gas has a starting boiling point of 95F. Heat a bit of gas in that dish with an oven thermometer for temps. The infrared gun may not be as accurate as a direct reading thermometer immersed in the gasoline.
I do agree with monitoring Temps at the track before modification. But depending on what the coolant Temps are you could fabricate a water jacket under the plenum and run water lines with a valve to control flow and have some control on how much it heats the bottom of the plenum
Uncle Tony, your timing is almost perfect. I've just been watching David Vizard talking about how much fuel needs to be vapour and how insulating the intake too much from engine heat can drop power. He also expounds on booster types and how much each type reacts to flow signals and how different designs of booster atomize fuel. Have you guys been coordinating this?
ford used to use an adaptor that went between the carb and intake that had water running through it. maybe you could find one and use that. that would give you engine heat at the intake.
Tony, I'm watching your intake vaporization vid now. You are on the right track with why and how the fuel reacts in the intake manifold but your not quite there yet. Yes, a street engine needs intake manifold heat for a few reasons. The most important is to vaporize the fuel from the carb so it can the ignited and produce heat in the cylinder. To do this it needs a heat source in the manifold either from the exhaust or coolant. Your correct in that the spark plug will not ignite raw fuel (see fouled spark plugs). You are also right that not 100% of the fuel mixture is consumed in the cylinder even if you have a FI system, this is why we have the EPA and CARB on our back. Yes. it is "emissions"! So, we know we can not burn all the fuel/air mixture in the cylinder BUT the more homogenous the mixture is the more efficient the combustion will be, in other words the more vaporized fuel in the mixture the more heat that is produced. Manifold heat is there to help vaporize the incoming fuel from the carb.. Fuel is discharged from the carb nozzles as a very fine mist (no vapor) when this mist enters the intake it MUST be heated to help vaporize it so it can be efficiently ignited in the combustion chamber to make a lot of heat! Heat in the cylinder is what pushes the piston down. As we say here in Detroit: "The more heat da better"! As for your experiment with the sheet of aluminum it is not exactly what is going on in the intake as the fuel mixture in the manifold is under vacuum and this helps the mixture stay homogeneous until it is in the cylinder and it is ignited by the SP. Chryslers 2.2l four cylinder carb engine had the intake under the carb heated with coolant. If you care to understand the physics behind this theory look up "The Heat of Vaporization" this will explain what happens when a liquid (gasoline) changes state from a liquid to a vapor. It will explain that there is heat loss from the liquid, it other words the vapor change will pull heat from the surrounding area. In the case of an intake manifold it will cool down. If you need an example of this just look at the A/C system in your car>" Heat of Vaporization"! Here is another, when you get out of the shower or a swimming pool, your skin starts to cool off immediately, this is the water on your skin evaporating and changing state form a liquid to a vapor>"Heat of Vaporization"! I was a engineer at Chrysler for 33 years, ten of those in the Carburetor Lab and on the dynos. I helped develop the 440-6 Pac system. Max
From what Google just told me, gasoline has a boiling range between 95*f and 395*f at atmospheric pressure. My understanding is this boiling point would be significantly reduced in vacuum through the venturi. Generally I believe lower intake temps are ideal. Full disclosure I'm an efi guy so my fuel is basically vaporized right out of the injector
I think you got the mixtures in a CCVC engine arse about Tony. The prechamber is the overly rich one and that lights the ultra lean mixture in the combustion chamber. A great idea for taking care of emissions.
This content is fascinating. I know others may think not but they don't get it. I love this subject. Atomizing and vapour and heat. Really, really good stuff that I'm going to be watching for your results with great interest. Thanks UT!
Good stuff Tony. I like the “choke” analogy for getting enough vapor to run a cold engine. David Visard talked about racing a Chrysler that stock had a hole to vent exhaust gas onto the bottom of the intake. He blocked the hole, but had to engineer a carb that would make very fine droplets. Darin Morgan says that the droplets in the chamber when it ignites, do nothing but heat your exhaust valve. George Bryce says it’s mostly just the pressure in the power stroke for the first half that do the work. That’s why you open the exhaust halfway down on the power stroke since the pressure isn’t doing much work anymore anyway.
In high school I had a 292 Chevy 6 with a 2bbl and dual 3-1 headers, I had the Same issue the truck ran great with a 10-1 compression and a ported head but would never launch of the line it would stall pop and rip away the answer years later I figured out the solution with a manifold heater
Great great video!! Made me think back. The Wright Brothers first motor had no carb. It dripped gasoline a plate that vaporized the gas as the motor heated up. How they got it to start I can not imagine much trust this arrangement to fly blows me away😜
We never had this issue on the /6 engine, but then we did run it in middle GA (Reynolds, GA) in the middle of Summer when the days were 80-95 degrees. We did run the engine for more than 5 or 6 minutes to warm it up. If you're going to heat the engine up to 200 +* coolant temperature you better be running EVANS coolant and not water. Evans doesn't expand or boil, you can run a 2lb radiator cap and not push any coolant out.
Science with Unk Tony! The way you explain things makes it so easy for me to digest. Thank you for sharing your knowledge with us all. It's valuable, really valuable to us that are just beginning this hotrod journey
Heat, vaporization and atomization. This is a great subject. There is so much to learn here. Everybody talks about how to get heat to the intake but does not talk about how to maintain it. Since this is just a drag car you let the engine warm the intake by idling the engine to operating temperature. This solves the problem without having to do any extra work or adding parts. What suggestions do you have for making this kind of engine streetable for daily driver use?
Need to get one of those thermal cameras to see how the heat is spreading throughout the runners. Can get some decent resolution thermal cameras now for a couple hundred dollars. Also good to see how the heat is distributed through the exhaust headers.
always have to get the calculator out when it comes to talking degrees with Americans 150 Fahrenheit is 65 degrees celsius. 65 degrees after 14 minutes of idling is still pretty cold say that the air temp coming is atomizing is probably getting below 30 degrees in the air charge
General modern day fuel starts to evaporated at 40 degrees. Now theres also E FUEL that e85 it starts way earlier but when it turns from a liquid to vapour its transition is much cooler again. Then pump gas. Cooling the air charge. Maybe run a E30 blend of octane 95 mixed with E85 per litre u shouldnt have to change metering blocks just alcohol gaskests. Might be able to run more advance timing and get better atomization. Because alcohol atomizes in colder temperatures. It maybe a video in its self the E30 trail the E30 carby the pros and cons there general setup video . Idea thought process video. 5 videos should pay for the idea
i remember they used to sell thin aluminum plates that acted as a heat shield fitted between the carb an intak/spacer. don't see them available anymore. of course a phenolic spacer is commonplace these days.
1/2 inch soft flexible plumbing copper is 5/8 inch outside diameter an fits nicely inside 5/8 heater hose. Use a few solder type elbows, and a looped intake heater is created.
I had a similar problem when I hot rodded a 69 Rambler American with a 258 inline six cylinder. Like the slant six the manifolds had a boss/flange where the manifolds bolted together. When I installed headers the intake lost the heat important for winter drivability. I made a steel plate to bolt to the intake manifold flange. Welded fittings to it and ran the heater hose through it. To regulate the temperature, plumb a shut-off valve into the line. Adjust it to get the temp you want. Or… Be a little more sophisticated rig a variable thermostat into the line. You could set it for the ideal temperature. It would be self regulating to keep the manifold temperature constant. I would put the variable thermostat downstream to keep the intake manifold at the temp you want.
Don't forget too, that when fuel boils off the heat of one's intake manifold, it is flash chilling the manifold. So the heat is instantly being lost to the fuel, meaning that just heating it with the ambient heat of the engine compartment will not last very long. You need a steady heat supply to keep it from icing out.
I blocked off the exhaust crossover on my 390 FE cyl heads in the hopes of extra HP what I ended up doing was creating a stumble at take off if the motor sits for more than10-15 minutes. It all makes sense now , thanks once again for the knowledge Uncle Tony. One of these days I'm going to send you a free f@#$ing pizza.
You are probably getting less air density also to match the higher fuel atomization. Maybe not the best compromise if you could still keep the denser air but with some better atomized fuel? It would be interesting to compare to some port injection. Good stuff
PS turning the carb around, was that data from Mopar about peak power or 60' times? Keep up the channel, your posts are very engaging to us old farts. Great job.
From what I remember from technology class in high school was 200 was the degree that metal molecules become the most compact and strongest for wear (that is a brief summary)
On inline engines trottle blades have to be parallel with crankshaft axle otherwise your get unequal fuel distribution and richness wich lead to poor engine performance and impossible tune up... For this reason you should rotate your holley carb 90 degres. As it is a 4 barrels carb you should rotate it with primaries outwards intake manifold (so on the driver side to get more low end torque ) and secondaries inwards for power By doing this you should quickly see somme change and get equal spark plugs colour all around your cylinders The accelerator pump have to be completly tune up (accelerator pump cam and discharge nozzle size) Heat soaking "hide" the real trouble and help but it is not the true cure, this is a technical solution for emissions cars
You want to get one of those Dutra or Aussiespeed 4 barrel manifolds for that. You'll probably pick up a few HP too, but I think the casting is actually thicker and that one you have looks pretty thin so it'll likely shed heat pretty quickly, the opposite of what youre trying to do. I was reading the Grumpy Jenkins power secrets book the other day, and he said they use off the shelf GM block heaters to pre heat the engine before running to temp. It's amazing what they achieved back then with only factory GM blocks and castings and a tenth of the aftermarket gear available compared to today!
I am running an Aussie Hurricane 2 bl intake (500 cfm 2300 Holley) and Dutra split manifold. My cold starts at noon show 140 degrees on the Autometer mechanical gauge. It loves 100 degree air temps and never a hard start problem hot or cold from fuel boiling in the carb. (im also at 4300 feet of elevation)
Infrared type thermometers you're using definitely get different readings from shiny Services versus dull surfaces . It will probably be close enough for your experiment but the temperatures can be way off.
You have to have a good heat source because vaporizing gas takes a lot of heat because of the latent heat of vaporization. When you heat the manifold up and it vaporizes some quantity of gasoline, that process takes a bunch of heat. More than you would think. It's basically an evaporative cooling effect.
Gasoline vaporizes as soon as it enters the combustion chamber. Hence the effectiveness of direct fuel injection where we inject liquid gasoline directly into the combustion chamber. I believe Tony's problem is a very poorly designed intake manifold.
@@ChrisPBacon-ok7ir In the engine it doesn't matter because there is more than enough heat to vaporize the fuel without cooling the cylinder. But he wants it to vaporize in the manifold where there is not as much heat
Furthermore the point of heating the plenum floor in particular is that the only fuel/air that sees the floor is stuff so rich/poorly atomized it's dropping out of suspension and trying to puddle, most of the flow just goes on by and is not heated. I think short of running exhaust under it like most American V8s it's kind of hard to have too much heat in that little spot.
Those IR temperature sensors have a setting (resistivity?) that effects the reported temperature. Perhaps not super critical but the actual measured temperature is affected by the metal type and surface treatment. So a black cast iron surface needs a different meter setting vs a painted/anodized aluminum one. it's been a while but I think a 5- or 10-degree Celsius error is possible.
a lot of the old inline manifolds had either a coolant passage or a plate to connect to the bottom of the manifold for exhaust gas to heat up the plenum
For the winter time in NJ back years ago I used to have a plate that would snap in between the headers. It was a place I could stick a Sterno heater under the intake to pre heat and warm it up before I take off .
I'm adding a hot air intake to air intake here in Houston to keep carb warm so I can run it lean. Ran 1.5" conduit against headers and connected to a extra snorkel welder to the stock style air filter housing. yet to be tested. it's a 1965 chevy 292 inline six with a 1 barrel in a 1980 square body!
I find this very interesting and its a good reminder that engine needs heat to operate correctly. Trying to make everything run cool is not always the best solution. Good Work Tony.
Just a suggestion, you spoke about the clocking of the carburetor and stated that it was what Chrysler engineers stated to do. I would keep an open mind and actually try the 4 positions available if it bolts up without added expense. Can you say, trust no one? With all the different variables going on with engine build, I would have to see for myself. I am not building a 6 with a 4 bbl, almost did but a '72 Chevy van presents driving issues with a carburetor where your leg should be as the manifolds available then had longer runners and probably still do. I canned the though of hopping up the engine. It actually got worse gas mileage than it's replacement, a '76 Chevy Van with a 350 and a Q--jet in front of another 3 speed column shift. I miss that truck. Both of them actually.
Why do people block off the heat passage in a intake manifold if they need heat to performe better and faster ? Super content. Scientificaly prooven datas as its best. From simple tools and materials. I understand better temperature degrees of pre- combustion vaporisation and and it's importance from driving and racing aspects.
I had a similar offenhouser manifold on a 6 cylinder jeep I had , and there was a heat riser coming off the exhaust manifold that heated the bottom of the intake manifold
In a different video you explain the different lengths of runners on the intake work at different RPM of the engine, so if you tunned the carburetor with the primary directly over the two shortest part of the intake runners, it mite work better at low RPM just saying it's worth trying
Very interesting problem Unk. Something you might try is a whiffer....A few ounces of acetone might start that cold gas burning. Depending on how much is used, you may have to back off the timing a bit....OR....Some winter blended gas. We use lots of it in the frozen north
Hello Tony, Your plan of not adding a hot spot under the carb until more testing is done is wise. Hell this who idea (though I think likely) could be completely wrong. If this does work adding a independently powered hot spot might well be a good idea (as you said). While the traditional way of doing this is with exhaust heating or coolant heating, there has also been electrical heating. Knowing your liking of low budget, you should know that the AMC 258 using the aluminum intake for the 2 barrel carb used this system. My thought is if you could have a hot spot under the carb with the remainder of the manifold relatively cold, the accelerator pump shot would hit the heater and vaporize. Given the relatively small mass of the heater, it would cool significantly. Any following air/gas would not be overly heated leading to a best of both worlds. Well in theory. p.s. I really like your videos, it is easy to show how to go fast using $, it is nice to see someone showing how to do it with skill and time. One can always turn to the $ if I run out of either. Fortunately I have not had to, as putting someone eases skill/time in my rig would not make it truly mine.
Tony, For my build, I used a Clifford Performance 6=8 coolant heated intake manifold with great results. I put a Holley HP 4150 on it with flawless results. It might be worth the time and $ if you want to stick with the 4 barrel. I was tempted to go with the triple 2 barrel Weber side draft kit, but it was a LOT more $. I can't wait to see what you finally settle on for the solution to this issue.
A MASTER MECHANIC/ RESTORER taught me; WHEN PROPERLY TUNED, TIMING SET & CARB SET PROPERLY ITS: 1 2 3 relatively quick pumps to floor & wait 10-15 seconds for fuel to atomize and turn to vapor. Then turn key and it fires everytime and idles smooth and clean!! IT WORKS!!
I like your tunnel ram demo. It explains my hair loss when I was 24. I was helping a buddy with a hesitation problem on his tunnel ram in a '65 Chev pickup. I was watching under the hood when he hit the gas. It lean back fired and this huge fireball came out from under the hood and burned the hair off the top of my head... My hair never came back... HAHAHA
tony I am an old gezzer, my fist attempt at racing was a Pontiac 261 6. I made a 3 signal manifold, it did basically the same thing, the first couple laps it was a dog, so I a made a heating device for /under the manifold and plumed heater water to it and back , it worked great
I have been trying to balance this low temp boiling point problem with street driven carburetors for many years. I demonstrated this once for a customer who brought me a small block Chevy/Nova combo. It was properly and neatly installed, all new and the tune was reasonably close. He had a steady power loss as the temp came up but no overheating, max 195f. I cooled the engine with a larger radiator down to a steady 170deg f. Helped a little but after several miles on a warm/hot day he still started losing power. I plugged the exhaust crossover in the intake and fabricated a heat shield with insulator gasket under the Edelbrock carb, helped more. I demonstrated the gas boiling in the carb by running the Edelbrock carb with the top off, manually keeping the fuel bowls filled. Did this from a cold start to full temp. As the carb bowls reached around 150 deg f you could see the fuel start to boil. It, the fuel, looked really hot boiling. When I stuck my finger in the boiling fuel in the bowl and held it there it demonstrated that it wasn't as hot as it looked.
Australia 1970 , Chrysler Australia used the mighty Valiant VG 4 door Pacer as their race cars , the standard 245 CI HEMI 6 was taken out to 251 CI and a 4 BBL Carter carb fitted , these cars went HARD ! kept up with the Ford and GM V8's on the long tracks and beat them on Australia's short tacks because of a 3 speed manual gearbox just using 2nd and 3rd .
But ,, as you say Uncle Tony they had no end of trouble with the 4BBL flooding when fitted the standard V8 way ,, it had big top end power but bogged and with a 3 speed was slow at start and out of the corners .
So what they did was exactly what you have done here and turned the 4BBL 90 degrees and it fixed that major problem , they became very competitive , then in 1971 the VG was superceded by the mighty VH 2 door Charger with 265 CI and triple Webbers and 280hp on the E38 3 speed and 320hp on the 4 speed E49 ,, Australia's fastest accelerating production car until 2002 when Ford made the 6 cylinder 'Barra' Turbo 6 , Falcon BA .
So from 1971 to 2002 they were the fastest ,, good history .
FYI , the 4BBL Pacer was named so , not because the had a 4 barrel carb , 4BBL stood for ' Four Big Bad Litre's '
Love Plan Z and look forward to Saturday ,
Thanks Uncle Tony .
P.S. I'm 78 years old so that theory has been around for a long, long time. All us Motor / Gearheads love your show. Been a MOPAR man since 1962, when I first got interested in speed and noise. Only new car I've ever owned was a 1964 Plymouth. Thank you very much for that idea ( RICHARD PETTY )❗👍🇺🇸🇺🇸🇺🇸🇺🇸🇺🇸✌
Remember fuel line going thru a "Coolcans" full of ice?
I remember people doing that, saying it improved performance.
But they were wrong. Or confused. Modern Dyno testing has proven that there's no HP gains from using a cool can. It's cold air that allows for better combustion. Cold air with hot, well atomized fuel is the golden ticket. 👍 😉
I've read something about cooling the return fuel/air mixture that didn't burn though.
But I believe that's for a fuel injected setup with a return system and all that stuff. 🤔
often that was a percolation issue as the mechanical fuel filter soaked up engine heat as the closed hood would trap heat in the summer. Roadkill once made the mistake of putting their Hemi Bee's fuel cell in the trunk of the super bee...no air flow..and they showed the fuel just bubbling away. so they spent $100 or more filling the trunk with bags of ice in 100 degree desert driving. as for performance, here's Richard Holdener's view
th-cam.com/video/ymFjK3PRL_A/w-d-xo.html
@@lilmike2710I just saw a dyno test on motor trend where they cooled the fuel and had huge gains
@@Ep1cPvP mmmhmmm 😏
We went to a local ice cream parlor and they would sell us dry ice to put in our cool cans.
The Clifford intake has a water box built into it. When I first installed that intake on my slant, I didn't hook it up because I didn't have any extra heater hose. I barely made it around the block. Next day, hooked it into the cooling system and I've been driving without a problem since.
I run all my engines at 160 Fahrenheit 70 Celsus. Dyno tests have shown this temp to make the most Horsetorques. So what you are saying makes total sense to me.
Fabricate an aluminum plate and bolt it to the bottom of your intake. Drill and tap two 1/2" pipe thread holes in the plate. Screw in two heater hose fittings. Attach a heater hose to each pipe fitting. You now have a heated intake manifold. So very simple and easy to do. Install a shut off valve on one hose to limit heat buildup. I made one for my old Plymouth flathead six and the drivability increased by 50%. You got this!
You could make a small heat exchanger out of copper pipe and stick it to the bottom of the intake and circulate coolant through it. Use a heater valve to regulate the flow so you can get the temp you want.
That would be an interesting experiment. Live temp readings as you monitor performance
@@Fleetwoodjohnwhat about a block heater on the manifold
Maybe some insulation wrapped around the runners would help if aluminum
intake cools down too quickly. Easier to test than some heat exchanger.
How many holes worth of weight is that?
Interesting. Add a temp sensor and choke cable to control the valve. Realtime. Aren't we full of ideas for UTG? 😅
Had two darts as a teen and both had slant sixes. The stock configuration had the exhaust manifold attached to the intake (And both cars would vapor lock on summer days). This configuration was the norm going back to the inline 4's, 6's and inline 8's of the 20 -30's.
On Chevy v8's I would restrict both heat runners with a piece of stainless sheet metal with a 1/4 inch hole in each because the Holly carb would warp the throttle plate and cause air leaks.
Another important thing with engine temp is making sure your oil gets to 215~220 to cook off any moisture that can accumulate in the crankcase from the PCV system sucking humid air in.
After several attempts with wraps and oil line cooling hoses we came up with either an oil cooler or a heater core for under the manifold. Installed a temp probe at the plenum to maintain temp at 150 to 165 degrees F. It was definitely a street killer of V8's. Just some thoughts.
I believe that as soon as you stomp the gas after the intake reaches 150 degrees, the intake charge (atmosphere) will suck most of that heat away, I have a homemade aluminum intake that even in the summer would develop a layer of frost/ice between the carb and the head, I wrapped the runner with the oil cooler hose and improved driveability enormously
I'd say it's highly likely you're correct, might finally get the manifold to heat soak and it just cools itself again.
Luckily it's a drag car so he only really needs the one warm hit
The gasoline vaporization requires energy as the gasoline molecules such energy out of the aluminum it will cool Key is to have sufficient mass or weight such that temp drop is within acceptable range
Interesting experiment would be to get manifold up to 150 at idle then monitor temperature under plenum as you pinch the throttle
Suck energy not such
@@ccpgmike620 I can assure you that as soon as the gas/air mixture hits the hot aluminum intake it (the intake) will lose heat like there's no tomorrow
@@davebaker9128 I agree! I did a very rough calculation: vaporizing 1 fluid ounce of gasoline can instantaneously drop a 20 pound aluminum manifold ~3 degrees F. Knowing specifics of fuel consumption and wieght of the slant manifold, Uncle Tony can ratio this estimate. BTW ethanol takes like twice as much energy to vaporize as crude oil based gasoline
Tony - I'd take the temperatures you were reading off that bare aluminum sheet with a BIG grain of salt - IR thermometers measure radiated infrared, and are typically calibrated for an emissivity (how readily a surface emits IR) of 0.95. Materials like that aluminum normally have an emissivity closer to half of that or less, and as a result will read lower than their actual temperature. To test it, try painting a part of the surface of your aluminum plate flat black, then heat it again and repeat your measurement with the IR gun, pointing it at both the painted area and the plain area right next to it. My bet is that the black area will "appear" a lot hotter to the thermometer, thought both are actually the same temp.
Just something to be aware of with IR thermometers, and something that's much more obvious with IR cameras that show an image - shiny metal will often look cold relative to more emissive things nearby. When measuring components on a circuit board that have metal cans, I usually put a piece of blue painter's tape on them to get a more accurate reading. The painted parts of the engine are likely much closer to reading their true temp, though still might show a bit cooler than they truly are. The header should be pretty much spot on.
Yes I completely agree. IR thermometers read lower on bare shiney metal. Paint the aluminum and redo the test.
Yes, even running cars look like the cold sky through my FLIR scope, only the tires, tail pipe, and halo under the car look hot, even when the sheet metal feels much warmer than ambient. Predator vision is a very strange world. I can see footprints with it for about a minute, but a paper target on a wood stand is completely invisible. "Paint" the target pattern with some water or spit in dry air and you can see it from over 100 yds.
Completely agree, I bet water would have boiled on the aluminum plate he was heating.
Painting the Al plate mat black is a good suggestion (the emissivity of the plack paint will be higher than 0.95, the standard setting of non adjustable IR temp guns). However uncle T's red shiny manifold is next up for guestimation of it's emissivity. Perhaps he would like to remove the red and spray it also mat black. The black paint will also help with the inlet manifold taking in more of the heat radiation of the exhaust manifold.
If you are correct ,put gas on the aluminum plate then record the reading when the gas starts to boil.
That reading will be your reference number to use when recording the time it takes the cold engine to start boiling gas in the intake
Back when I was a smog mechanic. I learned that a carburetor at 100° outside temperature would run at 32°/freezing, that's why guys at the out in the desert with their sand buggies added really huge Jets to make it not stumble, what they didn't know it was ice crystals forming inside the carburetor. Thanks for remind me of something I forgot. Keep up the good work I like the way you teach these new kids.
New kids don't run slant sixes.
Assuming those sand rails were running VW engines, I know exactly what you are talking about. Guys will put a big center mount carb but will not try and make any provision for heating the intake manifold. So then they were jetting rich for the stumble. With dual carbs and short intake manifolds all that goes away. But sand rails are used, well in the sand and desert. Having a carb hanging out on the side of your engine makes it quite vulnerable to rocks and dust. The center mount carb is for practicality. But it creates it’s own problems without intake heat.
Yes, that's why aircraft gas engines have carb heaters to prevent icing as incoming air at altitude cools as it accelerates into the throat of the carb.
@@joehoeing6590 , I'm aware of carburetor icing but this is a race car that doesn't get driven in winter and surely doesn't fly at high altitudes (hopefully). I still fault the design of the intake manifold and I also question the logic of that orientation of the carburetor since all air/fuel from the primaries is directed towards the front 3 cylinders and the rear 3 will be lean until the secondaries open. And if this is a vacuum secondary carb there is a chance that the secondaries will open late or possibly not at all.
As soon as I saw that Amway squirt bottle, I knew this was going to be a great UTG !
Not knocking the carb, but I now see why port injection is more controllable and preferred in modern engines when it comes to fuel efficiency and energy production. The injector is atomizing cold fuel right on the hot bits.
Garage 54 in Russia made a perspex intake manifold for a Lada, the result was interesting and probably shows what you are talking about at cold manifold temps. worth the 20 mins or so to watch
I’ve always wondered why small planes have Carb heat and was told it’s for icing. While I know that’s partly true, I’m sure this also helps vaporization.
Just for fun, I looked up C16: boiling begins at 193 and the upper end of vapor range [90%] is 226 degrees. That puts a midpoint around 209 degrees. Vaporization is done [no liquid remains] at 351 degrees. Jenkins was near a walking encyclopedia of all things combustion engine.
My wrenching mostly occurs in the context of my 1951 pickup with a slightly later 235 “Stovebolt” inline 6. This is a familiar issue to those with Stovebolts. The factory 216/235 setup works really well for a driver.
It’s a heat flap on the exhaust manifold that warms the intake under the carb. A bimetallic spring opens/ closes to regulate it.
One of the challenges for those who run aftermarket aluminum intakes or especially headers, is having a way to heat the intake absent the factory setup. Some intakes have provisions for a tube that supplies coolant or exhaust via copper lines. Some have rigged up their own setups. Lots and lots of disparate opinions on how well the aftermarket setups work, if at all.
For your application…a drag only car, I suspect your idea of a long warm up is the most logical place to start.
One concern: since you’re running with no charging system, will the battery voltage drop enough during the warmup to create ignition system weirdness?
After watching the entire video, I can suggest to get the engine temp to normal operating temp. If I can recall, the thermostat in those engines were 180/190 deg. I'm old, so I may be off on the thermostat. But it would help the engine efficiently to warm it up before you run it.
I had a 1980 LeBaron that the previous owner put large piece of aluminum under the carb. And a shroud under the exhaust to the intake. 30 pluse years being a mechanic, was wondering what they were thinking. Now I know why my slant 6 ran so good. You figured it out. Sad part is somebody beat you to it. Love your channel. Keep it up.
You gotta understand Uncle Tony some people are just here to criticize you they don't need to look at the video and see what really happened or what you put on the car when you build it they just look for any reason to complain
But if you don't have ignorant haters you're doing something wrong
I agree with @ homotorsports . Will the higher air fuel mixture flow during burnouts cool off the plenum more than it can reheat before you make your run. You should test it before the weekend so you don't waste the trip to find out it doesn't reheat and it does the same as your other runs and bogs.
Jeep 258’s had an electric plenum heater under the carb in the intake..
And a water line. Gonna hook one or both back on tomorrow now that I have my carb sorted. Couldn't tune out a mid speed detonation. Brand new power valve wasn't opening. Now I can get the intake heat working again.
You're on to something here. I had a 39 year career as a Chief Engineer in a power plant and during that time I worked along with quite a few combustion engineers. We wouldn't have used air pre-heaters, on power boilers, ahead of burner windboxes if hot air didn't speed combustion. There is a lot going on in an engine intake manifold. A cool dense air mixture is a good thing going in but once the fuel enters the plenum it should pick up enough heat to give a kick (you call flash) to the fuel mixture to get efficient combustion so there is no stumble or bog coming off the line. I'd be careful adding auxiliary heat. You're probably better with an extended warm up time if you can make due with that.
Fred
Tony, a simple and low-cost mod is to install a temp sender to measure the manifold temp. not the air temp! the temp of the metal of your manifold. Your pick of a coolant or oil temp sensor, then use a toggle switch to display it on a suitable OEM gauge! FWIW use a toggle switch with enough poles to include the switching needed for indicator lamps..
I wonder if you drilled and tapped the intake to take a temp sensor, let the sensor butt up against the casting, so it reads the casting temp then add a temp gauge for it. It may not read the exact temp but I'm sure you could likely figure out a delta using a gauge and the temp gun. That could make for some fun and easy data collecting and testing.
Good idea..then put the electric fan sensor in it.
That is the next logical step. Good idea
Tony I went through this year's ago. The direct connection manual is wrong. If you turn the carburetor sideways, all your plugs will burn clean everybody that follow follows the direct connection manual, has to run plugs of varying ranges
As proof, the same manual shows you how to weld a 2 barrel Plat on, rember? And they welded it sideways for racing. I daily drove one for years, tried every way just to be sure. Hollies, carters, even factory thermoquad and even GM quadrajet? Many would suffice, but the best I found was the one off my cross ram Hemi. Also mounted sideways...
Why not make a plate that bolts up like the stock exhaust manifold and run engine coolant through the plate? You could run a 160 thermostat and hopefully get your 150 under the carb. I used to be in the Ford 300 scene and that’s what we did. Your correct on how the carb needs to be facing. The 300’s would do the same thing without heat. With no heat my 300 was not drivable at outside temps under 55 degrees F. I love the Slant content btw
You are over thinking hot rodding the slant six with that POS intake.
You need a 883 close ratio four speed 4:56 gears ,13 to 1 compression , big solid flat tappet cam , high rpm and light weight fiberglass body parts to make that manifold work with a four barrel carburetor for racing.
Put a Gear vendors on it if you want to drive it.
Wicked good vid Uncle Tony! I love how you break it all down in easy ways to understand.
Can't wait to see the vid of Plan Z's next pass!
Cheers from Maine!
This is awesome and great info makes sense why vapor lock is more of a thing than it used to be
Well, since you brought up how the tunnel ram works, I'd get a custom tunnel ram made for a slant six that lifts and centers the carb.....problem solved????? Besides-how cool would that be :)
The old 361s in the D600s used water heater intakes to keep them at or just below the coolant temp.
It is interesting to note that not a single slant 6 racer heats the intake and none of them is having your problems. Maybe you you should reach out the "rusters" owner and ask his advise.
Use a heated coolant from the heater feed ports to a heat a block bolted to the bottom of the intake. You could use a heater control valve to regulate temperature.
Maybe add something to reach that temp quicker then shut it off
Genuine hotrod stuff right there. Thanks Uncle Tony!
G'day, I recon a heat riser pipe, bolted to underside of manifold, extending down to exhaust. 4-6 inch dia. or multiplesmaller pipes.
If it's too hot, drill holes in it. If not hot enough, add more pipes.
Anyway, good luck with it.
Balancing the heat is tricky. Hot air expands, takes up more space in the runner. Same with fuel. I think it was Smokey that said you wanted it as cold as possible from the outside air, to the plenum, just shy of allowing carb icing, then you wanted it to stay cold to about the point where the intake transitions into the head but not so cold that water vapor would build ice in the runner. From that point forward, you wanted as much heat as you could get, just to the point that the fuel would vaporize around 15-20% of the wet fuel. That mixture allowed the front end vapors to ignite better and create the heat you needed to get closer to optimizing the burn while still maximizing the amount of mixture you can get crammed into the cylinder. In Vizards book, he talks about coating intake valves and getting more HP, but his engine was more of a road racing build than a drag build. It would make sense that you would gain in a long distance engine that spends more time at full power but I think the drag racing engine would benefit less except at the top end of the track. You're needing starting line vaporization. Looks like you are on the right track. Maybe narrow up the valve seat widths on the intakes to allow less heat transfer and give a sharper edge to shear the fuel next time you have the head off.
Interesting video, how about building a tunnel ram for the slant. Simple exhaust tubing and a box for a plenum up through hood. Would be a cool experiment.
I have seen so many tuning problems that just come down from a cold intake manifold. Many always blame the carb. End up with an over jetted mess that still doesnt run well. Uncle Tony clearly shows that in this video. Like he said, i also grew up around blocked off intake heat for power. But on a hot street car, that can be a real PITA... I used to get on this forum that mostly talked on Ford 240/300 inline six truck engines. The first thing most guys did was put exhaust headers on, a open plenum 4 barrel intake. Then try and live with it as a daily driver. I tried to help many on there with their tuning issues, some figured it out. Adding a coolant plate under the intake plenum to warm it, is a good bandaid fix. On my truck set up the same way, but no tube headers. I made my own split cast iron exhaust manifolds, that retained the factory heat riser bolted the the intake manifold. My 390 Holley 4 barrel works perfect, with the jets that came in it... Any inline six engine suffers from too cold of an intake, because it hangs away from the engine heat, unlike a V8. That is any inline six modified like this... Uncle Tony, i believe you will have to bite the bullet, and add some form of heat to your Slant six intake, ( more than you want). Just to get the car to launch well, even if it costs you some top end power... Love your videos !
Smoky Yunick used to swear on 200-210 degrees for circle track engines the hot air engine had a inlet temp of 450 degrees
Absolutely excellent video Tony !! Your explanation made perfect sense especially when you heated the plate !! Great work !!
plenum temps before n after a burnout should tell you the cooling power at full throttle.
Great experiment! I have heard of the water passage heater blocks for those manifolds. Never had an issue with my cast iron (keyword cast iron) manifold.
You're on the right track, but lest we forget the cooling effect of the velocitized incoming charge of air and fuel combined with the surface temp of the warmed manifold, a further reduction/loss of temp will be seen inside the plenum. I say on the right track because more heat soak of the plenum will be needed to achieve your theoretical latent vapor process. Keep truckin!
I always enjoy your content Uncle Tony.
It seems you broke from your normal way of optimization of the existing systems. The engineer may have had more than fuel economy in mind when they made the exhaust manifold bolt to that section of the intake, possibly they ran into the same issue you are fighting during the R&D.
Keep up the good work on Plan Z!
I love how you're experimenting. Very cool. As far as testing vaporization on the aluminum plate, I'd suggesting making a plate about the size of the carburator baseplate in the form of a dish. That alum. plate you used probably has a big temp gradient making it inaccurate. The google says gas has a starting boiling point of 95F. Heat a bit of gas in that dish with an oven thermometer for temps. The infrared gun may not be as accurate as a direct reading thermometer immersed in the gasoline.
I do agree with monitoring Temps at the track before modification. But depending on what the coolant Temps are you could fabricate a water jacket under the plenum and run water lines with a valve to control flow and have some control on how much it heats the bottom of the plenum
Uncle Tony, your timing is almost perfect. I've just been watching David Vizard talking about how much fuel needs to be vapour and how insulating the intake too much from engine heat can drop power.
He also expounds on booster types and how much each type reacts to flow signals and how different designs of booster atomize fuel.
Have you guys been coordinating this?
ford used to use an adaptor that went between the carb and intake that had water running through it. maybe you could find one and use that. that would give you engine heat at the intake.
Excellent testing…Just wondering if the the intake temp will drop during the burnout from the air and fuel flow…You can test that before you go
It could cool off the plenium more than it can reheat before the run.
Tony, I'm watching your intake vaporization vid now. You are on the right track with why and how the fuel reacts in the intake manifold but your not quite there yet.
Yes, a street engine needs intake manifold heat for a few reasons. The most important is to vaporize the fuel from the carb so it can the ignited and produce heat in the cylinder. To do this it needs a heat source in the manifold either from the exhaust or coolant. Your correct in that the spark plug will not ignite raw fuel (see fouled spark plugs). You are also right that not 100% of the fuel mixture is consumed in the cylinder even if you have a FI system, this is why we have the EPA and CARB on our back. Yes. it is "emissions"! So, we know we can not burn all the fuel/air mixture in the cylinder BUT the more homogenous the mixture is the more efficient the combustion will be, in other words the more vaporized fuel in the mixture the more heat that is produced. Manifold heat is there to help vaporize the incoming fuel from the carb.. Fuel is discharged from the carb nozzles as a very fine mist (no vapor) when this mist enters the intake it MUST be heated to help vaporize it so it can be efficiently ignited in the combustion chamber to make a lot of heat! Heat in the cylinder is what pushes the piston down. As we say here in Detroit: "The more heat da better"! As for your experiment with the sheet of aluminum it is not exactly what is going on in the intake as the fuel mixture in the manifold is under vacuum and this helps the mixture stay homogeneous until it is in the cylinder and it is ignited by the SP. Chryslers 2.2l four cylinder carb engine had the intake under the carb heated with coolant. If you care to understand the physics behind this theory look up "The Heat of Vaporization" this will explain what happens when a liquid (gasoline) changes state from a liquid to a vapor. It will explain that there is heat loss from the liquid, it other words the vapor change will pull heat from the surrounding area. In the case of an intake manifold it will cool down. If you need an example of this just look at the A/C system in your car>" Heat of Vaporization"! Here is another, when you get out of the shower or a swimming pool, your skin starts to cool off immediately, this is the water on your skin evaporating and changing state form a liquid to a vapor>"Heat of Vaporization"!
I was a engineer at Chrysler for 33 years, ten of those in the Carburetor Lab and on the dynos. I helped develop the 440-6 Pac system. Max
From what Google just told me, gasoline has a boiling range between 95*f and 395*f at atmospheric pressure. My understanding is this boiling point would be significantly reduced in vacuum through the venturi. Generally I believe lower intake temps are ideal.
Full disclosure I'm an efi guy so my fuel is basically vaporized right out of the injector
I think you got the mixtures in a CCVC engine arse about Tony. The prechamber is the overly rich one and that lights the ultra lean mixture in the combustion chamber. A great idea for taking care of emissions.
Excellent diagnosis. I'm sure you will run faster Saturday.
This content is fascinating. I know others may think not but they don't get it. I love this subject. Atomizing and vapour and heat. Really, really good stuff that I'm going to be watching for your results with great interest. Thanks UT!
I never thought about this experiment he just done. It's simple and interesting.
Good stuff Tony. I like the “choke” analogy for getting enough vapor to run a cold engine.
David Visard talked about racing a Chrysler that stock had a hole to vent exhaust gas onto the bottom of the intake. He blocked the hole, but had to engineer a carb that would make very fine droplets.
Darin Morgan says that the droplets in the chamber when it ignites, do nothing but heat your exhaust valve.
George Bryce says it’s mostly just the pressure in the power stroke for the first half that do the work. That’s why you open the exhaust halfway down on the power stroke since the pressure isn’t doing much work anymore anyway.
In high school I had a 292 Chevy 6 with a 2bbl and dual 3-1 headers, I had the Same issue the truck ran great with a 10-1 compression and a ported head but would never launch of the line it would stall pop and rip away the answer years later I figured out the solution with a manifold heater
Tony you are not an engineer, you are a scientist and a magician!
Great great video!! Made me think back. The Wright Brothers first motor had no carb. It dripped gasoline a plate that vaporized the gas as the motor heated up. How they got it to start I can not imagine much trust this arrangement to fly blows me away😜
We never had this issue on the /6 engine, but then we did run it in middle GA (Reynolds, GA) in the middle of Summer when the days were 80-95 degrees. We did run the engine for more than 5 or 6 minutes to warm it up. If you're going to heat the engine up to 200 +* coolant temperature you better be running EVANS coolant and not water. Evans doesn't expand or boil, you can run a 2lb radiator cap and not push any coolant out.
Science with Unk Tony! The way you explain things makes it so easy for me to digest.
Thank you for sharing your knowledge with us all. It's valuable, really valuable to us that are just beginning this hotrod journey
Heat, vaporization and atomization. This is a great subject. There is so much to learn here. Everybody talks about how to get heat to the intake but does not talk about how to maintain it. Since this is just a drag car you let the engine warm the intake by idling the engine to operating temperature. This solves the problem without having to do any extra work or adding parts. What suggestions do you have for making this kind of engine streetable for daily driver use?
Need to get one of those thermal cameras to see how the heat is spreading throughout the runners. Can get some decent resolution thermal cameras now for a couple hundred dollars. Also good to see how the heat is distributed through the exhaust headers.
always have to get the calculator out when it comes to talking degrees with Americans 150 Fahrenheit is 65 degrees celsius. 65 degrees after 14 minutes of idling is still pretty cold say that the air temp coming is atomizing is probably getting below 30 degrees in the air charge
General modern day fuel starts to evaporated at 40 degrees. Now theres also E FUEL that e85 it starts way earlier but when it turns from a liquid to vapour its transition is much cooler again. Then pump gas. Cooling the air charge. Maybe run a E30 blend of octane 95 mixed with E85 per litre u shouldnt have to change metering blocks just alcohol gaskests. Might be able to run more advance timing and get better atomization. Because alcohol atomizes in colder temperatures. It maybe a video in its self the E30 trail the E30 carby the pros and cons there general setup video . Idea thought process video. 5 videos should pay for the idea
i remember they used to sell thin aluminum plates that acted as a heat shield fitted between the carb an intak/spacer. don't see them available anymore. of course a phenolic spacer is commonplace these days.
The vapor fuse thing makes sense. Good explanation. I’m interested to see how it plays out.
1/2 inch soft flexible plumbing copper is 5/8 inch outside diameter an fits nicely inside 5/8 heater hose. Use a few solder type elbows, and a looped intake heater is created.
I had a similar problem when I hot rodded a 69 Rambler American with a 258 inline six cylinder. Like the slant six the manifolds had a boss/flange where the manifolds bolted together. When I installed headers the intake lost the heat important for winter drivability.
I made a steel plate to bolt to the intake manifold flange. Welded fittings to it and ran the heater hose through it. To regulate the temperature, plumb a shut-off valve into the line. Adjust it to get the temp you want. Or… Be a little more sophisticated rig a variable thermostat into the line. You could set it for the ideal temperature. It would be self regulating to keep the manifold temperature constant.
I would put the variable thermostat downstream to keep the intake manifold at the temp you want.
Also when you are using the choke it's actually dropping the atmosphere pressure to allow the fuel to vapourize.
You could always mount a block heater on the bottom of the intake underneath the carburetor to preheat the intake.
Love your videos, keep it up.
Add a pyromiter temp gauge and keep track of the bottom of the intake
Don't forget too, that when fuel boils off the heat of one's intake manifold, it is flash chilling the manifold.
So the heat is instantly being lost to the fuel, meaning that just heating it with the ambient heat of the engine compartment will not last very long.
You need a steady heat supply to keep it from icing out.
I blocked off the exhaust crossover on my 390 FE cyl heads in the hopes of extra HP what I ended up doing was creating a stumble at take off if the motor sits for more than10-15 minutes. It all makes sense now , thanks once again for the knowledge Uncle Tony. One of these days I'm going to send you a free f@#$ing pizza.
You are probably getting less air density also to match the higher fuel atomization. Maybe not the best compromise if you could still keep the denser air but with some better atomized fuel? It would be interesting to compare to some port injection. Good stuff
PS turning the carb around, was that data from Mopar about peak power or 60' times?
Keep up the channel, your posts are very engaging to us old farts.
Great job.
From what I remember from technology class in high school was 200 was the degree that metal molecules become the most compact and strongest for wear (that is a brief summary)
Jeeze, you're like the HVAC Guy of Engines over here. Brilliant explanation.
On inline engines trottle blades have to be parallel with crankshaft axle otherwise your get unequal fuel distribution and richness wich lead to poor engine performance and impossible tune up...
For this reason you should rotate your holley carb 90 degres.
As it is a 4 barrels carb you should rotate it with primaries outwards intake manifold (so on the driver side to get more low end torque ) and secondaries inwards for power
By doing this you should quickly see somme change and get equal spark plugs colour all around your cylinders
The accelerator pump have to be completly tune up (accelerator pump cam and discharge nozzle size)
Heat soaking "hide" the real trouble and help but it is not the true cure, this is a technical solution for emissions cars
You want to get one of those Dutra or Aussiespeed 4 barrel manifolds for that. You'll probably pick up a few HP too, but I think the casting is actually thicker and that one you have looks pretty thin so it'll likely shed heat pretty quickly, the opposite of what youre trying to do. I was reading the Grumpy Jenkins power secrets book the other day, and he said they use off the shelf GM block heaters to pre heat the engine before running to temp. It's amazing what they achieved back then with only factory GM blocks and castings and a tenth of the aftermarket gear available compared to today!
I am running an Aussie Hurricane 2 bl intake (500 cfm 2300 Holley) and Dutra split manifold. My cold starts at noon show 140 degrees on the Autometer mechanical gauge. It loves 100 degree air temps and never a hard start problem hot or cold from fuel boiling in the carb. (im also at 4300 feet of elevation)
Infrared type thermometers you're using definitely get different readings from shiny Services versus dull surfaces . It will probably be close enough for your experiment but the temperatures can be way off.
You have to have a good heat source because vaporizing gas takes a lot of heat because of the latent heat of vaporization. When you heat the manifold up and it vaporizes some quantity of gasoline, that process takes a bunch of heat. More than you would think. It's basically an evaporative cooling effect.
Gasoline vaporizes as soon as it enters the combustion chamber. Hence the effectiveness of direct fuel injection where we inject liquid gasoline directly into the combustion chamber. I believe Tony's problem is a very poorly designed intake manifold.
@@ChrisPBacon-ok7ir In the engine it doesn't matter because there is more than enough heat to vaporize the fuel without cooling the cylinder. But he wants it to vaporize in the manifold where there is not as much heat
Furthermore the point of heating the plenum floor in particular is that the only fuel/air that sees the floor is stuff so rich/poorly atomized it's dropping out of suspension and trying to puddle, most of the flow just goes on by and is not heated. I think short of running exhaust under it like most American V8s it's kind of hard to have too much heat in that little spot.
Those IR temperature sensors have a setting (resistivity?) that effects the reported temperature. Perhaps not super critical but the actual measured temperature is affected by the metal type and surface treatment. So a black cast iron surface needs a different meter setting vs a painted/anodized aluminum one. it's been a while but I think a 5- or 10-degree Celsius error is possible.
a lot of the old inline manifolds had either a coolant passage or a plate to connect to the bottom of the manifold for exhaust gas to heat up the plenum
For the winter time in NJ back years ago I used to have a plate that would snap in between the headers.
It was a place I could stick a Sterno heater under the intake to pre heat and warm it up before I take off .
I'm adding a hot air intake to air intake here in Houston to keep carb warm so I can run it lean. Ran 1.5" conduit against headers and connected to a extra snorkel welder to the stock style air filter housing. yet to be tested. it's a 1965 chevy 292 inline six with a 1 barrel in a 1980 square body!
I find this very interesting and its a good reminder that engine needs heat to operate correctly. Trying to make everything run cool is not always the best solution. Good Work Tony.
Just a suggestion, you spoke about the clocking of the carburetor and stated that it was what Chrysler engineers stated to do. I would keep an open mind and actually try the 4 positions available if it bolts up without added expense. Can you say, trust no one? With all the different variables going on with engine build, I would have to see for myself. I am not building a 6 with a 4 bbl, almost did but a '72 Chevy van presents driving issues with a carburetor where your leg should be as the manifolds available then had longer runners and probably still do. I canned the though of hopping up the engine. It actually got worse gas mileage than it's replacement, a '76 Chevy Van with a 350 and a Q--jet in front of another 3 speed column shift. I miss that truck. Both of them actually.
Why do people block off the heat passage in a intake manifold if they need heat to performe better and faster ?
Super content.
Scientificaly prooven datas as its best.
From simple tools and materials.
I understand better temperature degrees of pre- combustion vaporisation and and it's importance from driving and racing aspects.
I had a similar offenhouser manifold on a 6 cylinder jeep I had , and there was a heat riser coming off the exhaust manifold that heated the bottom of the intake manifold
I've made copper gaskets back in the day, and it's pretty easy. Copper will transfer heat from the head as soon as it heals up.
Great video, I really like the way you show your work. With this Saturday being another step to prove your theory.
In a different video you explain the different lengths of runners on the intake work at different RPM of the engine, so if you tunned the carburetor with the primary directly over the two shortest part of the intake runners, it mite work better at low RPM just saying it's worth trying
Very interesting problem Unk. Something you might try is a whiffer....A few ounces of acetone might start that cold gas burning. Depending on how much is used, you may have to back off the timing a bit....OR....Some winter blended gas. We use lots of it in the frozen north
Hello Tony,
Your plan of not adding a hot spot under the carb until more testing is done is wise. Hell this who idea (though I think likely) could be completely wrong. If this does work adding a independently powered hot spot might well be a good idea (as you said). While the traditional way of doing this is with exhaust heating or coolant heating, there has also been electrical heating. Knowing your liking of low budget, you should know that the AMC 258 using the aluminum intake for the 2 barrel carb used this system.
My thought is if you could have a hot spot under the carb with the remainder of the manifold relatively cold, the accelerator pump shot would hit the heater and vaporize. Given the relatively small mass of the heater, it would cool significantly. Any following air/gas would not be overly heated leading to a best of both worlds. Well in theory.
p.s. I really like your videos, it is easy to show how to go fast using $, it is nice to see someone showing how to do it with skill and time. One can always turn to the $ if I run out of either. Fortunately I have not had to, as putting someone eases skill/time in my rig would not make it truly mine.
Tony,
For my build, I used a Clifford Performance 6=8 coolant heated intake manifold with great results. I put a Holley HP 4150 on it with flawless results. It might be worth the time and $ if you want to stick with the 4 barrel.
I was tempted to go with the triple 2 barrel Weber side draft kit, but it was a LOT more $.
I can't wait to see what you finally settle on for the solution to this issue.