The Dyno run at 11° total timing demonstrates how poorly an engine runs when the distributor advance mechanism gets stuck so that it no longer provides any advance.
From my experience tuning my standalone, AFR doesn't change much when you adjust timing. That's why I dial in the fuel with a safe timing first, adjust timing for best safe torque, then go back and make small adjustments to the fuel as needed.
being 55, this was he most informative info i have ever seen. (carb guy) i tuned cars this way, but i had know idea that these big changes were so minimal, thanks rich!
Thank You! Since AFR gauges have become so popular, time and time again I see people trying to tune to the gauge. “ I’m too fat (@12.5 hg) at part throttle”, thinking the engine needs to be near perfect AFR throughout the entire operating range they spend hours tuning one area out and now they are fat or lean somewhere else. Round and round they go. Unless it’s too Lean or grossly fat and has drivability issues don’t sweat AFR! People, after the initial setup of the carb spend your time dialing in the TIMING. Optimizing timing will improve drivability and maximize peak power.
I've been doing my own tuning for a very long time and something I've always tried to explain to people is no two engines are identical.... even in laboratory conditions. It can be the same bore same block same piston the same valve springs.... literally everything identical and they're going to tune different . It can be really close but they will not be the same. That's why I always laugh when people say I want that identical set up and I wanted to run identical but the tuning is just a jet size different or a degree of ignition timing off or whatever but it's never literally identical and that's something people just don't understand. I'm glad you're explaining that. I love watching your videos. I always learn something. you have to be open-minded and be willing to learn. if you think you know everything you probably don't know anything. Lol remember persistence overcomes resistance every time
This is your best one yet Richard. Dispelling all the internet BS in a single bound 😊 I would like (at some future point) to see you do a test with either the Holley or other brand carb style EFI system and do a similar test. Why? I’ve only used Holley and FiTech, what I learned is that the fuel tables are ‘elastic’ because they will self learn/tune, but the timing table is a ‘hard’ parameter set by the user. I honestly thing a video in this area would be very helpful to a lot of folks. Once again, awesome job on this video!! Cheers
More SBC, my heads spinnin' Mr Holdener. When I bought my SBC it was straight out of a Drag Bracket car (72 Chevelle, ran 10.20s), was told by the previous owner that carb was an on/off switch (tricked out 850 DP), so I put a 750 HP DP out of the box on it---set the idle circuits, been drivin' it for 2 1/2 years, reasonable throttle response (was told it likes 36/38 total timing, runnin' 28/30 on the street) and doesn't foul plugs (Autolite R133s), and I'm a happy camper. EVERYONE says they can get way more changin' every little thing. Thanks Richard, I'll continue with mine the way it is. Oh, if I needed more I'd tighten the valves a little, bump the timing, put straight 112 in it and put the 850 back on it, it does Rock&roll like that!
A long time ago, I read a book about the exploits of Smokey Yunick. This is very much like the that. Think, Test, Think again... Smokey was famous for bending rules and always looking for small advantages. One thing he always stressed was air fuel balance between cylinders. One lean cylinder can destroy a motor. Also timing balance, This is not as big a problem anymore, as most of the new distributors are electronic and very good. Have you ever looked into how timing balance effects how much timing an engine will accept? How slop in the timing chain and cam gear / Distributor drive gear effects this? I remember him talking about gear drives instead of timing chains. One thing many people don't realize is that the oil pump being driven off the distributor gears keeps all the gears and chains tight, also keeps the distributor gear up against it's thrust washer. Minimizing these timing variations. It also damps out the vibrations from the cam opening and closing the valves. There is so much to this subject.....
This is GOLD! Its answered so many of questions, I didn't know how to ask. Gives me a better understanding on how loose I can be with timing up top and still keep a detonation barrier.
I've been a professional mechanic for over 30 years. I used to get TBI Chevy trucks in my shop for tune ups. The factory setting for initial timing is 0 degrees but most would be at 2 to 4 degrees atdc probably due to gear or timing chain wear. I would advance the timing to 4 degrees btdc. That is about as much as you can go before you get detonation. This made my shop very popular. Almost all the owners with these trucks would either call or stop by a day or two later and exclaim how the truck had never run so good, even when it was new. I never divulged my secret tuning trick, lol!
I just love your stuff... i am almost 70, have been doing stuff that basically, what all the so called experts say you cant do, and getting great results a budget $... Now you come along and prove what i have been saying and doing on paper.... Here in Australia we had in start 2 Holden V8,s one was 253 CI & 308 CI the smaller one had a 2 barrel and was well just boring, and the bigger had a Rochy Q jet quiet ok.. i used to take the 4 barrel and manifold COMPLETE, and unchanged and bolt it on the small one with amazing results, really woke it up, but much ridicule... O its two big, it will flood the motor, bla bla bla, the proof was in the driving, snappy, great economy and rev like a 2 stroke.. Again thanks,, i feel more than vindicated.. keep up the incredible site.. many people should be happy with what you are doing... Eddie C4 Australia.
@@ilovethephilippines8991 . No doubt that putting a 4 barre intake and carb on a 2 barrel engine is going to make it go alot better. But to say that a 253 Holden V8 was alot quicker to rev is just plain bullshit. I have built many 253's and 308's over the years and I also had a lot to do with the Commodore Cup series that ran the 253. You had to do alot of work with heads and cam to make them even slightly better than standard to rev. The blue 253 was slightly better with a standard 4 barrel but by that stage they were getting choked by pollution crap.
Richard, Thank You for backing up what I've been preaching for decades. I have witnessed, and I'm sure you have too, people take band new out of the box carbs that ran almost optimum and loose power fiddling around with jets/air bleeds/pump shots, ETC.... I've seen "tuners" try to prove how good they are by running shit on the ragged edge for 4 HP just to badmouth the other guy. This will shut a lot of the self proclaimed tuning Jedi's up. This old gearhead always learns a thing or two from your comparisons, BRAVO!!!!
Timing does not directly affect A/F and vise versa. The relation comes down to engine temperature. That is why you tune A/F for optimal volumetric efficiency, and the you tune timing for power (minimum best timing). Something I tend to do in EFI is to put a base timing around the whole table, say 10 degrees, then tune the VE table, and then tune the time properly. That way I reduce stress from the engine in half and helps me troubleshoot anything before something breaks. That's just my method. Cheers and great video!
If you have screw in emulsion bleeds you can lean or richen an rpm range but it still has an effect everywhere like you said. Play with them enough and rejet to correct the overall afr you can somewhat tune out bad areas just not specific rpms. But I'm sure you know that but most don't.
I actually have had these questions for a few years. Now that I am installing an AFR gauge to a carburated car I will benefit a lot from this. Thank you for sharing Mr. Richard.
Efi and carbs are the same - on a carb you use a screwdriver and efi you use a laptop. If you have a wideband o2 sensor on it just keep an eye on it and remember at what rpm range you need to change.
Timing is about syncing up peak cylinder pressure with the mechanical sweet spot based on the geometry of the crank.... AFR is about using all the air molecules available to oxidize fuel. Carbs and fixed timing distributors are pretty blunt tools, hence their demise in the OEM car world. You can definitely tune carbs to change the shape of the AFR curve, but jetting mostly moves it up or down. Things like individual 4 corner tuning of the carb and evaluating per cylinder AFR and per cylinder fill with intake manifold alterations or even rocker arm ratio changes per cylinder - all that is the beauty of having an engine dyno. Sure not going to do that for the sunday driver, but race a 350 HP motor on a road course and the difference is dramatic when working to get the area under the curve maxed out. I am sure Richard knows all this, so i guess this comment is geared to the weekend warriors here. BTW GREAT VIDS, I just found your channel and the first half dozen vids I watched are great. Jealous of your setup! :)
Thanks for clearing up this set of misconceptions . The old timers who grossly over advance Ignition timing then drill out the jets were badly mistaken.
Richard, your videos are the best. The best. So much information with the proof behind it. When I was in my twenties I worked in a machine shop and went to the tracks drag racing Wednesday nights and weekends. The shop I worked for had a NA sbc rail and a NA sbc Vega. The a machine shop had no dyno. We track tested everything. In my mind, I was good with carbs and since I was twenty years old at the time most everything I said was blown off. So I collected a few carbs and did the air horn clean up on the vacuum secondary 750's and the double pump 850's. I tested flow with a flow bench at a local carb shop who I met at the track. So tracks with lots of grip I gave them the 750 and tracks that had little traction I gave em the 850. The 850 was lazy on the line but would make it up on the top end and the 750's flow a lot more then 750 cfm. The first few were good and then the changes I made didn't seem to affect them much at all. I would never tell the guys what was done to the carb's, I would just give it to them and ask them to "Try this one, I did something for this track". So when one of the guys would say "The carb needs a set of 78's in the secondary's" I would say it has 78's in the secondary's because I found out it doesn't make any change as long as the carb is a good working carb. It automatically, mechanically adjusts to every application, very hot days, cold days, dry, humid, except altitude (which we never dealt with). After a while the timing never changed and the carbs were never questioned. Cam's, cam timing and valve adjusts made more of a change then either of the other two. The info in these video's you make confirm and explain why. That is one thing I never could do. Thanks for all these videos. I don't see how they could be any better. EDIT: I do have a complaint. The advertisements on your video. Most of us know you get paid something if we watch the advertisement without "Skipping" and if we click on the ad you get a little extra for that. It's always been my thing to leave the adds running and watch em, if there interesting and even click on them to let them play in the background. But here's the thing. Your video is a little over 17 minutes long and the first advertisement is over 38 minutes long. You're getting 38 minute ad's tacked onto your videos. I can watch a 15 second or a 30 second ad or even as much as a 3 minute ad. Even worse is the 38 minute ad that's selling something that makes a 102 year old person have the same energy as if they were 60 years old. Okay so I am 63 years old so I know first hand how 63 years old feels like. I still bang gears in my 70 427 Nova, but I don't think I want any hundred and two year olds out in the streets banging gears, just sayin. I don't know if you have control over what or how long the ad's are or if TH-cam controls that but I am pretty sure that any ad over 5 minutes long is going to get skipped and some video's have more then one of these ad's.
Been tuning for years, but it's very interesting to see it all graphed out in detail. Lol, when I was a kid I used to attach my distributor to a choke cable so that I could retard the timing, to make the engine sound like it was cammed while circling the drive-ins.
@@xmo552 Yes, we used to have a Model A, and it had a retard lever on the steering column. I think it was there for starting with the crank. Otherwise you might break your arm...
I don't think you will see much difference between 160 and 205 for ECT. The big difference is heat soaking the intake and the increases that has to IAT, Intake Air Temp is where it's at.
@@iamblaineful On my carbed Pontiac it would slow down a little anything over 160. My LT1 corvette slows a tenth of a second or more going from 170 to 190. Probably loses 10HP.
When I worked in the Netherlands at the official HRC Superbike and Supersport 600 team as head porter and engine tester I did those tests also. As for example in South Africa Kyalami circuit the temperature above the road exceeded 50 degrees Celsius causing the coolant temperature rising to 115 degrees Celsius........ Well.... as at 75 degrees the hp from a 600cc was about 125 hp.......at 90 it would be down to say 118 hp. But even worse was that the curve of the hotter engine was at all not as straight and tight as the 75 degree Celsius coolant engine. Hugely affecting driveabillity. I did not dare testing beyond 105 degrees as engine yhen really lost power
180-185F is a pretty good spot IMO if you're racing and want the engine to last a while but aren't too concerned about maximum life or efficiency. Though 180 is about the point that will lead to unexpected tolerances in the engine and often increased cylinder wear, from an experiment I saw a long time ago. Also, colder temps mean it might take longer to clear condensation out of the oil/crankcase. Hotter can limit the total advance you can run since it might increase the propensity for pre-detonation/knock, plus overall things getting hotter like intake tract or fuel system, which decreases air density and power. Higher temps also mean larger temperature cycling of the materials, so more stress and also more movement due to difference in expansion rates, such as aluminum head on iron block, or intake/exhaust manifolds to head. Also more expansion in terms of head thickness and gasket thickness, which can compress the gasket or strain the fasteners more. Hotter does improve efficiency when that's a concern, like endurance racing or street fuel efficiency. That's why a lot of engines in the last 20ish years have pushed the normal operating temp up to 200-220 (maybe emissions reasons also). Torque-to-yield bolts have probably helped address the expansion issues with higher operating temps.
Bench racers and keyboard cowboys getting shut down with basic facts never gets old... Thanks Richard. You're stuff is always entertaining and informative.
That was another great video Richard. I have a Moates Quarterhorse on my Fox Mustang. I have been playing with fuel and timing with good results. It is nice to know that timing doesn't mess up air fuel ratio. I always learn something in your videos.
And some aren't. I've had times where, no matter what "demon tweak" I made, I couldn't go any faster. Because I wasn't addressing the real problem, the true cause of my slowness, whatever it was. I was messing with jets, power valves, squirters, vacuum diaphragm springs, pump cams, timing, point gap, ad nauseum. The 600 carb was too small. New 750, untouched, right out of the box, and Boom, 3 tenths.
I was literally thinking about the timing vs af ratio on my 78 blazer last night! Then this video showed up on my notifications this morning. You’re a wizard 🧙♂️ mr holdener!
Richard would you be able to do an exhaust heat wrap dyno comparison to see if it adds scavenging? Try like DEI titanium wrap vs ebay fiberglass vs nothing maybe..
I know it causes embrittlement of the header tubes. It ruining mine in 3 years. Now I paint them with the DEI wrap paint. It lasts so long people think they are coated!
More of an underhood temp deal in my opinion and it's been proven to damage headers if you over wrap but I've done it correctly on a few cars n been fine.
Would not add much scavenging if at all but could lower engine bay temperatures which could have an effect. Even, so, ceramic-coated headers would do that better.
It won't do anything but ruin your headers in the long run..it will keep under hood temps down..thats a fact. Thats about the only thing it does EDIT: Late to the show..everyone covers what I said..lol
Running a 95 Chrysler Jeep 4.0 in lieu of the 72 AMC 258 in a 72 IH Scout II with a FAST EASY EFI 2.0 handling ignition and EFI. 100+ days of fiddling with it on the road says timing has way more effect than AFR’s. Thankfully I can adjust it all with the handheld controller!😉. Thanks for the excellent talk and graphs. I’ll be putting what I have learned to use!!
You know what I think it is? I think it's that old school guys are used to idle tuning a carb/distributor car. In that scenario it feels super interactive because as you lean the idle it accelerates, as you add timing it accelerates, etc. But that's not about power, it's just about the engine running better as it gets dialed in and thus speeding up.
Thanks for this Rich. I had a 500hp 440 that I didn't think quite ran what it should. During a refresh, when degreeing the new cam I found the damper timing mark was off by six degrees. What I thought was 38 total was 32. I was thinking I cost myself a good bit of power. Your vid helps me think it was not such a big deal. Thanks again!
You are the man! I can’t say enough about how much I appreciate all the work you do. I think all the car mags people read for years and year conditioned us to think that changing timing means you need to adjust the timing as well as the other way. Thank you for clearing out the smoke.
This was a great comparison, to see the actual figures. It lines up with my experience in that a carburetor is quite forgiving, it may be a miss match at times but it will work and work well in the top end and note that a street car will be more streetable with a carby that is not too big for bottom end and mid range driveablity. The timing is an interesting one too, I have learnt through experience the engine only needs enough timing to make it happy, no more and no less. On some high comp engines running on pump octane I have had to pull the total timing back to 25deg to stop detonation and once I found that sweet spot for the fuel one particular cleveland engine was more exciting to drive than a similar spec engine with less comp and more timing. How I think about spark timing is its all about how quick that flame front moves across the top of the piston and produces the maximum pressure to push that piston back down the bore, if there is not enough timing some of that pressure is in effect wasted and too much just slows down the piston as the pressure is made too early. I like to run a soft tune on my drag car, running race fuel with 32 total so on race day I can enjoy the racing. The engine sounds sweet and happy there and makes good power and all the comments you mentioned that others say I have heard too.
Another great post....I'm glad to see this as my wife loves to drive my Malibu that has a 388 stroker in it and I would take 16* if timming out of it so she would stay out of the ditches..my carb buddy experts would always bring up fouling the plugs....I never hurt the plugs....be safe..
Another fantastic information video! But you do a lot of power adder videos, so it would be cool to see how the timing curves might vary between nitrous, turbos, and centrifugal blowers? Like does nitrous work best with a flat timing "curve?" Does a turbo need more timing at higher rpm? Is a centrifugal blower "curve" linear or curved? Keep up the great work!
Great video. In the late 90s and onwards i street tuned my efi for fuel economy, running much leaner on mild acceleration and cruise compare to factory cars which at the time would run too rich everywhere other than on closed loop. I noticed manufacturers leaned it off over the years but took them along time
I'm gonna guess here, but the newer engines have knock sensors and much more efficient combustion chambers, aluminum heads, and fuel injector placement and the quality of the fuel injector itself.
@@superkillr I would say nothing to do with engine tech, more about tuning knowledge. For example in Aust we have the Ford straight 6 from 1989 to 2002 is basically the same engine with alloy head and efi with knock however the tune was greatly refined over the years with much improvements with fuel economy. With older engines it used to come out of closed loop under very light load and very rich under light acceleration when in reality you can hold stoich in a much larger window which they did in later tunes
Having tuned my own EFI car from scratch, and had the benefit of a "rich/lean" knob, where I could change the AFR's +/- 25% at a constant timing and load while driving, I can confirm that what Richard Holdner says in this video is the truth... super easy to "feel" how insensitive the engine is to small changes in AFR's at the same timing and load, but much easier to feel changes in timing for a constant AFR and load.
I thought about this and a few thoughts, I went from sea level racing in seattle/bremerton to 5000 feet in albuquerque and had to take 6-10 jets out to get rid of the rich running and sheer laziness, this was on a 400ish hp 302 *basically a 1.90 valved performer rpm combo with a 650 dp* I didn't have a drag strip handy to figure out timing so i backed it down a couple degrees because I didn't know the fuel, but otherwise it ran fine it was just lazy. So I had a good idea what was going to happen with the rich a/f, the timing I wasn't expecting a lot of change maybe .5 on the a/f .3 is pretty close to my thoughts. For non carb guys that maybe a jet.. maybe 2 at most in fueling changes. What I'd like to see is dyno tuned on the dyno vrs actual changes needed for the drag strip, timing vrs jetting and mph changes *et isn't a good indicator mph is because it takes hp to make mph vrs car weight* If you have any kinda testing on that, I'd like to see it as I could never afford a dyno tune.
Leaned it down to 72 on a vacuum secondary 750. Went up to on the shooter! The bandage on the daily driver was great. Ran as much timing as I could get away with! It was a 306 in a foxbody Capri! The 31 shooter really helped it to catch its breath till the old 750 vacuum secondary was ready! Drove it every day! A 50cc pump and 31 shooter made it think it had a bigger carb on it!
Thank you for an informative and unbiased assessment on this subject. I suspect many have fallen for the BS given out over the years, its good to know that guys such as your good self are out there.
This applies to EFI and carb: volumetric efficiency from idle to max RPM will dictate both fuel and timing. Dial in the fueling with safe timing and then adjust timing for max torque (MBT). EFI lets you add timing under light loads with leaner fueling (lean mixture burns slower, needs more timing) and increase MPG. WOT on a well tuned EFI setup with very efficient heads (chamber) typically only wants 18-22* You don’t adjust fuel to accommodate timing changes- if anything the reverse is true, at least in EFI for most efficient burn/ MBT at a given (or all) RPM.
I'm no engine guru by any means but I could not see a relationship between Ignition Timing and AF. Now advancing / retarding the cam I could see a little because the signal would change a little. Great video, I learn a lot here.
You need to wear a cape and mask and introduce yourself as Captain horsepower !!! Or Major torque !!! Another great video Sir and all the best to you and yours.
Great as always. As a young man I always heard 14.7:1 is the optimal A/F ratio. I always thought 12:1 was too rich. Not that we measured this scientifically or anything. We measured by ET slip. What about those Chrysler lean burn motors? I heard they ran in the 16:1 range. Of course, they were pitiful dogs for motors. I learned the timing thing early. I put a 340 4 BBL on my 318 Dart, set the timing by ear and went cruising that night. Did okay and even beat another 340. The next day I put the light on it only to find out I was 15 degrees too low. It was a tire fryer after that.
So glad you did this video. It’s almost daily that I get asked to find people 30+ HP on a car or 10+ HP on a bike that’s NA with just a tune. Now going from stock ecu programs to a custom tune can indeed net that realm of power gains, but if your vehicle is already tuned and you just changed a muffler section or changed intake filters that minute 1/2 degree or so of timing or few tenths AFR I adjust in either direction is not going to break the dyno with massive power gains lol.
Side note: I would like to see this test done on a boosted application and would be especially curious of the timing aspect and it’s effects. I say this because I really can pick up significant power on say a turbo setup with small incremental timing changes in most cases, but it would make sense to magnify NA gains on a boosted setup. I would just be curious to see if the changes follow suit to doing it NA just by way of larger gains.
I’d love to see these AF charts in Lambda. I switched to lambda when I went to e85 and it made life easier on the gm stuff.. good stuff as always Richard!
A billet metering block with multiple bleeds in fuel well can trim the curve somewhat with rpm , not efi but there is a something there . But fantastic information , thanks again .
While I'm not gonna argue that, can you imagine the number of top carb tuners Richard has been exposed to over the years? Do you think they don't know about billet this and new sensational carb product that?
Basic question Basic car Hypothetical old carb'd... "If I could" what would be "ideal": 1)idle AFR 2)acceleration AFR 3)cruise AFR 4)WOT AFR Thanks guys 🙏
Depends on the engine combination. For fun, 14.7, 12.6, 13.6-8, 12.6. There's too many variables to define an absolute AFR. There are some generalizations that work ok but even still, every engine is different.
Timing was my big problem for lack of performance during RMRW. The mechanical advance wouldn't advance more than 8 degrees even at more than 4000 rpm. I had to run the initial timing at near 30 degrees in order to get 36 degrees total. My 1/4 mile times shown I was down near 100 hp.
11 degrees? I'd think that to be a very hot engine to walk around when it was running, glowing headers and all that. Good times. Something worth mentioning is that the jet sizes on a Holley may seem like the hole diameter difference is small but it can make a big difference because the area is calculated by pi*R^2. As an example going from a 74 jet to a 79 jet is an area increase of about 20%. In this case it means going from a 74 jet to a 100 jet is about a 60% increase in fuel! Vizard said to get the timing close, adjust the AFR then dial in the timing in his Holley book because there would be minimal change. Definitely validated in this dyno testing. Were you even within the range of the WB on those super rich tests? Not sure where the limit hits on a higher end WB but on an LSU4.2 I believe you'd have been out of range rich e.g. it could have been even richer than it showed up as. Based on my guestimates I'd think you'd be nearer to 8:1 if not dipping into the 7s. RE:changing part of the RPM band on the carburetor. Obviously you're not going to change say a 100 or 1000 RPM band but I would think you could alter the PVCRs, the HSABs and the Emuslifiers to influence the higher RPM power. Typically that is a big proportion of the stuff that's done to a blow through carb e.g. reduction of the HSAB, increase the PVCR and decreasing or elimination of the emulsification. Well that and vent tube extensions in a lot of cases. On a QJ that curve would be influenced by the taper rate of the metering rods. I'd think it to be very noticeable in some of the smog era rods compared to the performance era stuff.
Great video Richard - this kinda explained why the First Gen Z/28s came with a Holley that was almost identical to the Holley on the L- 78 396 cars of the same era
Hey Richard, glad to see another video, you always make such great content. If there’s one thing I could request is to see a 5.4 2valve ford from a junkyard with a few bolt ons and boost, I know they aren’t the greatest engines for power, but they are super common and I havent seen much content about them ever.. thanks!
If the subject was about how these changes effect emissions and fuel mileage there would probably be a much more significant difference in their values , and perhaps that`s where some confusion exists, but then you have to start talking about regulations and five gas analyzers and that would just take a lot of the fun out of it. Fuel injection technology has come a long way and we can probably thank regulators and engineers for that because now days you can actually talk about high performance and high efficiency in the same conversation. Thanks for another great video.
True if you can hear it. Open header racecars dont make that real easy, unless it's real bad. By that point you have probably hurt the engine. Plugs on the other hand can tell you, if you know what to look for. I.E.- small shiny dots on the plug, is ONE indication of detention.
Excellent video! One thing I've noticed in my car WRT timing, We run 40 degrees in first gear, 37 in second and 34 in third gear and the car does ET better.
Cool thank you for this Richard! Learned a lot. I thought messing with the A/F ratio would affect the engine to a larger degree. I have no experience tuning tho unless u count changing parameters on my lil pocket plug in tuner 🤣
Richard - this video is so valuable in terms of information and education. Thank you so much! I have always wondered how much timing changes affect air fuel ratios, and now I know! One more thing Richard - I love your tests you do with large boost numbers, can you do some testing with big big nitrous? Like 500-600hp worth of direct port nitrous? I’d love to see the low amounts of ignition timing used with that much nitrous. SBC, BBC or LS I’m sure us nitrous guys will love it!
I've had engines I've built be extremely sensitive to timing like 40-50hp going from 32-36* and other engines that almost dont gain hardly anything doing the same change, it really depends on the combination, and that's why imho you always want to dyno tune a new engine because everyone is different!
@@dennisrobinson8008 no, E85 isn’t common at the pump up here the the PNW and I mainly do NA engine builds so I haven’t played with it much but I’d like to!
@@DSRE535 I can imagine! On a 400-500HP N/A engine they are getting 5-10% gain with E85 and adjusting the timing 2-5 degrees. Plus it's a more forgiving fuel for detonation. If you were going to be ALL E85 all times, you could literally run 14-15:1 on the street N/A, and 12:1 boosted with E85.
@@DSRE535 Damn! I had a thought too, so there is a loss in MPG of about 20-30% over gas. I was curious if going up in the compression ratio can get over this somewhat by making the engine more efficient? Each pt of CR is worth 4% on gas, so going from 10:1 to 13:1 is 12% gain in torque across the board.
My comment is 455. ☺ Thank YOU, Richard. U may have saved my engine. I'm in agreement: give up some horses to ride another day. I'm sending this to some buddies. 👍
Would the A/F change on the major timing sweep just be a reflection of unburnt fuel therefore throwing off an accurate reading of what is going on in the combustion chamber?
Very educational video, Richard! Do you ever do part-throttle power pulls to see what the A/F is under conditions more like regular street daily driver conditions? Below certain torque levels, A/F can be right at 14.5 for good fuel economy. Then can the carb be tuned to get 12.5 at WOT to keep the power and detonation margin?
The Dyno run at 11° total timing demonstrates how poorly an engine runs when the distributor advance mechanism gets stuck so that it no longer provides any advance.
I had a friend that refused to fix that probably had a 80 horsepower 305.
From my experience tuning my standalone, AFR doesn't change much when you adjust timing. That's why I dial in the fuel with a safe timing first, adjust timing for best safe torque, then go back and make small adjustments to the fuel as needed.
being 55, this was he most informative info i have ever seen. (carb guy) i tuned cars this way, but i had know idea that these big changes were so minimal, thanks rich!
Thank You! Since AFR gauges have become so popular, time and time again I see people trying to tune to the gauge. “ I’m too fat (@12.5 hg) at part throttle”, thinking the engine needs to be near perfect AFR throughout the entire operating range they spend hours tuning one area out and now they are fat or lean somewhere else. Round and round they go. Unless it’s too Lean or grossly fat and has drivability issues don’t sweat AFR!
People, after the initial setup of the carb spend your time dialing in the TIMING. Optimizing timing will improve drivability and maximize peak power.
I've been doing my own tuning for a very long time and something I've always tried to explain to people is no two engines are identical.... even in laboratory conditions. It can be the same bore same block same piston the same valve springs.... literally everything identical and they're going to tune different . It can be really close but they will not be the same. That's why I always laugh when people say I want that identical set up and I wanted to run identical but the tuning is just a jet size different or a degree of ignition timing off or whatever but it's never literally identical and that's something people just don't understand. I'm glad you're explaining that. I love watching your videos. I always learn something. you have to be open-minded and be willing to learn. if you think you know everything you probably don't know anything. Lol remember persistence overcomes resistance every time
thousands of Corvettes roll off the production line. All are within 1%. dynos can't read within 1%. that's not going to take different tuning.
Persistence overcomes resistance 💪😁♂️
This is your best one yet Richard.
Dispelling all the internet BS in a single bound 😊
I would like (at some future point) to see you do a test with either the Holley or other brand carb style EFI system and do a similar test.
Why?
I’ve only used Holley and FiTech, what I learned is that the fuel tables are ‘elastic’ because they will self learn/tune, but the timing table is a ‘hard’ parameter set by the user. I honestly thing a video in this area would be very helpful to a lot of folks.
Once again, awesome job on this video!!
Cheers
More SBC, my heads spinnin' Mr Holdener. When I bought my SBC it was straight out of a Drag Bracket car (72 Chevelle, ran 10.20s), was told by the previous owner that carb was an on/off switch (tricked out 850 DP), so I put a 750 HP DP out of the box on it---set the idle circuits, been drivin' it for 2 1/2 years, reasonable throttle response (was told it likes 36/38 total timing, runnin' 28/30 on the street) and doesn't foul plugs (Autolite R133s), and I'm a happy camper. EVERYONE says they can get way more changin' every little thing. Thanks Richard, I'll continue with mine the way it is. Oh, if I needed more I'd tighten the valves a little, bump the timing, put straight 112 in it and put the 850 back on it, it does Rock&roll like that!
A long time ago, I read a book about the exploits of Smokey Yunick. This is very much like the that.
Think, Test, Think again... Smokey was famous for bending rules and always looking for small advantages.
One thing he always stressed was air fuel balance between cylinders. One lean cylinder can destroy a motor.
Also timing balance, This is not as big a problem anymore, as most of the new distributors are electronic and very good.
Have you ever looked into how timing balance effects how much timing an engine will accept? How slop in the timing chain and cam gear / Distributor drive gear effects this?
I remember him talking about gear drives instead of timing chains.
One thing many people don't realize is that the oil pump being driven off the distributor gears keeps all the gears and chains tight, also keeps the distributor gear up against it's thrust washer. Minimizing these timing variations.
It also damps out the vibrations from the cam opening and closing the valves.
There is so much to this subject.....
Smokey Legend
Thanks Richard, this is 30 years of experience in under 20 min.
This is GOLD! Its answered so many of questions, I didn't know how to ask. Gives me a better understanding on how loose I can be with timing up top and still keep a detonation barrier.
I've been a professional mechanic for over 30 years. I used to get TBI Chevy trucks in my shop for tune ups. The factory setting for initial timing is 0 degrees but most would be at 2 to 4 degrees atdc probably due to gear or timing chain wear. I would advance the timing to 4 degrees btdc. That is about as much as you can go before you get detonation. This made my shop very popular. Almost all the owners with these trucks would either call or stop by a day or two later and exclaim how the truck had never run so good, even when it was new. I never divulged my secret tuning trick, lol!
Does the computer get cranky on those if you past 2*-4*?
One of best teaching videos I have seen on the subject.
I just love your stuff... i am almost 70, have been doing stuff that basically, what all the so called experts say you cant do, and getting great results a budget $... Now you come along and prove what i have been saying and doing on paper.... Here in Australia we had in start 2 Holden V8,s one was 253 CI & 308 CI the smaller one had a 2 barrel and was well just boring, and the bigger had a Rochy Q jet quiet ok.. i used to take the 4 barrel and manifold COMPLETE, and unchanged and bolt it on the small one with amazing results, really woke it up, but much ridicule... O its two big, it will flood the motor, bla bla bla, the proof was in the driving, snappy, great economy and rev like a 2 stroke.. Again thanks,, i feel more than vindicated.. keep up the incredible site.. many people should be happy with what you are doing... Eddie C4 Australia.
A old thong slapper reving like a 2 stroke. Mate you are dreaming.
@@MJTAUTOMOTIVE yeah mate what ever you say... lololol
@@ilovethephilippines8991 . No doubt that putting a 4 barre intake and carb on a 2 barrel engine is going to make it go alot better. But to say that a 253 Holden V8 was alot quicker to rev is just plain bullshit. I have built many 253's and 308's over the years and I also had a lot to do with the Commodore Cup series that ran the 253. You had to do alot of work with heads and cam to make them even slightly better than standard to rev. The blue 253 was slightly better with a standard 4 barrel but by that stage they were getting choked by pollution crap.
Richard, Thank You for backing up what I've been preaching for decades. I have witnessed, and I'm sure you have too, people take band new out of the box carbs that ran almost optimum and loose power fiddling around with jets/air bleeds/pump shots, ETC.... I've seen "tuners" try to prove how good they are by running shit on the ragged edge for 4 HP just to badmouth the other guy. This will shut a lot of the self proclaimed tuning Jedi's up. This old gearhead always learns a thing or two from your comparisons, BRAVO!!!!
Timing does not directly affect A/F and vise versa. The relation comes down to engine temperature. That is why you tune A/F for optimal volumetric efficiency, and the you tune timing for power (minimum best timing).
Something I tend to do in EFI is to put a base timing around the whole table, say 10 degrees, then tune the VE table, and then tune the time properly. That way I reduce stress from the engine in half and helps me troubleshoot anything before something breaks. That's just my method. Cheers and great video!
If you have screw in emulsion bleeds you can lean or richen an rpm range but it still has an effect everywhere like you said. Play with them enough and rejet to correct the overall afr you can somewhat tune out bad areas just not specific rpms. But I'm sure you know that but most don't.
💪💪👍👍 best motorhead channel.. ..
Appreciate that
Engine head! AAAHHHHH!
I actually have had these questions for a few years. Now that I am installing an AFR gauge to a carburated car I will benefit a lot from this. Thank you for sharing Mr. Richard.
How about a tuning basics series for the diy.
There's no magic bullet theory it takes years to learn how to tune like this guy theres just no way to teach all that in a few simple vidys
Nightwrencher channel
@@bill2178 I understand it is a concept that takes alot of time, trial and error but some basic rules to follow and where to start wouldnt hurt.
@Radeonr9280x A I was referring to efi not carb setups.
Efi and carbs are the same - on a carb you use a screwdriver and efi you use a laptop. If you have a wideband o2 sensor on it just keep an eye on it and remember at what rpm range you need to change.
Timing is about syncing up peak cylinder pressure with the mechanical sweet spot based on the geometry of the crank.... AFR is about using all the air molecules available to oxidize fuel. Carbs and fixed timing distributors are pretty blunt tools, hence their demise in the OEM car world. You can definitely tune carbs to change the shape of the AFR curve, but jetting mostly moves it up or down. Things like individual 4 corner tuning of the carb and evaluating per cylinder AFR and per cylinder fill with intake manifold alterations or even rocker arm ratio changes per cylinder - all that is the beauty of having an engine dyno. Sure not going to do that for the sunday driver, but race a 350 HP motor on a road course and the difference is dramatic when working to get the area under the curve maxed out. I am sure Richard knows all this, so i guess this comment is geared to the weekend warriors here. BTW GREAT VIDS, I just found your channel and the first half dozen vids I watched are great. Jealous of your setup! :)
Thanks for clearing up this set of misconceptions . The old timers who grossly over advance Ignition timing then drill out the jets were badly mistaken.
Richard, your videos are the best. The best. So much information with the proof behind it. When I was in my twenties I worked in a machine shop and went to the tracks drag racing Wednesday nights and weekends. The shop I worked for had a NA sbc rail and a NA sbc Vega. The a machine shop had no dyno. We track tested everything. In my mind, I was good with carbs and since I was twenty years old at the time most everything I said was blown off. So I collected a few carbs and did the air horn clean up on the vacuum secondary 750's and the double pump 850's. I tested flow with a flow bench at a local carb shop who I met at the track. So tracks with lots of grip I gave them the 750 and tracks that had little traction I gave em the 850. The 850 was lazy on the line but would make it up on the top end and the 750's flow a lot more then 750 cfm. The first few were good and then the changes I made didn't seem to affect them much at all. I would never tell the guys what was done to the carb's, I would just give it to them and ask them to "Try this one, I did something for this track". So when one of the guys would say "The carb needs a set of 78's in the secondary's" I would say it has 78's in the secondary's because I found out it doesn't make any change as long as the carb is a good working carb. It automatically, mechanically adjusts to every application, very hot days, cold days, dry, humid, except altitude (which we never dealt with). After a while the timing never changed and the carbs were never questioned. Cam's, cam timing and valve adjusts made more of a change then either of the other two. The info in these video's you make confirm and explain why. That is one thing I never could do.
Thanks for all these videos. I don't see how they could be any better.
EDIT: I do have a complaint. The advertisements on your video. Most of us know you get paid something if we watch the advertisement without "Skipping" and if we click on the ad you get a little extra for that. It's always been my thing to leave the adds running and watch em, if there interesting and even click on them to let them play in the background. But here's the thing. Your video is a little over 17 minutes long and the first advertisement is over 38 minutes long. You're getting 38 minute ad's tacked onto your videos. I can watch a 15 second or a 30 second ad or even as much as a 3 minute ad. Even worse is the 38 minute ad that's selling something that makes a 102 year old person have the same energy as if they were 60 years old. Okay so I am 63 years old so I know first hand how 63 years old feels like. I still bang gears in my 70 427 Nova, but I don't think I want any hundred and two year olds out in the streets banging gears, just sayin. I don't know if you have control over what or how long the ad's are or if TH-cam controls that but I am pretty sure that any ad over 5 minutes long is going to get skipped and some video's have more then one of these ad's.
Been tuning for years, but it's very interesting to see it all graphed out in detail.
Lol, when I was a kid I used to attach my distributor to a choke cable so that I could retard the timing, to make the engine sound like it was cammed while circling the drive-ins.
variable timing combined with drive by wire-I like it
@@richardholdener1727 Lol.
@@michaelangelo8001
Early cars like Model T and motorcycles were like that.
@@xmo552 Yes, we used to have a Model A, and it had a retard lever on the steering column.
I think it was there for starting with the crank. Otherwise you might break your arm...
@@richardholdener1727 Early drive-by-wire technology lol
This answers questions I've had in the past. As a bracket racer, I wonder how much power changes with coolant temp? 130 to 160 to 180 and 200.
I don't think you will see much difference between 160 and 205 for ECT. The big difference is heat soaking the intake and the increases that has to IAT, Intake Air Temp is where it's at.
@@iamblaineful On my carbed Pontiac it would slow down a little anything over 160. My LT1 corvette slows a tenth of a second or more going from 170 to 190. Probably loses 10HP.
When I worked in the Netherlands at the official HRC Superbike and Supersport 600 team as head porter and engine tester I did those tests also. As for example in South Africa Kyalami circuit the temperature above the road exceeded 50 degrees Celsius causing the coolant temperature rising to 115 degrees Celsius........
Well.... as at 75 degrees the hp from a 600cc was about 125 hp.......at 90 it would be down to say 118 hp. But even worse was that the curve of the hotter engine was at all not as straight and tight as the 75 degree Celsius coolant engine. Hugely affecting driveabillity.
I did not dare testing beyond 105 degrees as engine yhen really lost power
Engine masters did a test
Brulé said: oil hot coolant cold would be the ideal situation...
180-185F is a pretty good spot IMO if you're racing and want the engine to last a while but aren't too concerned about maximum life or efficiency. Though 180 is about the point that will lead to unexpected tolerances in the engine and often increased cylinder wear, from an experiment I saw a long time ago. Also, colder temps mean it might take longer to clear condensation out of the oil/crankcase. Hotter can limit the total advance you can run since it might increase the propensity for pre-detonation/knock, plus overall things getting hotter like intake tract or fuel system, which decreases air density and power. Higher temps also mean larger temperature cycling of the materials, so more stress and also more movement due to difference in expansion rates, such as aluminum head on iron block, or intake/exhaust manifolds to head. Also more expansion in terms of head thickness and gasket thickness, which can compress the gasket or strain the fasteners more. Hotter does improve efficiency when that's a concern, like endurance racing or street fuel efficiency. That's why a lot of engines in the last 20ish years have pushed the normal operating temp up to 200-220 (maybe emissions reasons also). Torque-to-yield bolts have probably helped address the expansion issues with higher operating temps.
Great video alot of good information
Bench racers and keyboard cowboys getting shut down with basic facts never gets old... Thanks Richard. You're stuff is always entertaining and informative.
Glad you like them!
Best video/test yet! The most usable information in one video of all of your videos that I have watched (and I've watched a lot)..... well done!
Excellent info! I’m learning more from your channel then I did in school lol keep it up!
That was another great video Richard. I have a Moates Quarterhorse on my Fox Mustang. I have been playing with fuel and timing with good results. It is nice to know that timing doesn't mess up air fuel ratio. I always learn something in your videos.
Most of carb tuning is drive-ability, some cars/combos are sensitive to changes
And some aren't. I've had times where, no matter what "demon tweak" I made, I couldn't go any faster. Because I wasn't addressing the real problem, the true cause of my slowness, whatever it was. I was messing with jets, power valves, squirters, vacuum diaphragm springs, pump cams, timing, point gap, ad nauseum. The 600 carb was too small. New 750, untouched, right out of the box, and Boom, 3 tenths.
@@donellmuniz590yes! that is why having an afr gauge is soo helpful
@@donellmuniz590 That sizing, I meant WOT & idle are easy, the hard part is all that's inbetween
@@loko306 I'm stubborn and use my plugs, I'll try an afr gauge someday
Afr is simple to measure today, but how about timing? Egt? Or is that secondary? some kind of a broad band knocking sensor maybe?
Thanks. So ignition timing has a bigger effect in HP TQ.
Awesome experiment. Best video on the subject.
I am starting to get hooked on all the info in your videos!
Love this channel no BS just the cold hard truth. Keep them coming
I was literally thinking about the timing vs af ratio on my 78 blazer last night! Then this video showed up on my notifications this morning. You’re a wizard 🧙♂️ mr holdener!
Great way to show the results of such dramatic changes.
Just think back in the day we would do this by scent of the exhaust plug reading and the sound by ear.
Still do, lol. On the carbureted stuff, at least. Only got one left.
Excellent video interesting thanks.
Richard would you be able to do an exhaust heat wrap dyno comparison to see if it adds scavenging? Try like DEI titanium wrap vs ebay fiberglass vs nothing maybe..
I know it causes embrittlement of the header tubes. It ruining mine in 3 years. Now I paint them with the DEI wrap paint. It lasts so long people think they are coated!
I doubt we see any change on the dyno
More of an underhood temp deal in my opinion and it's been proven to damage headers if you over wrap but I've done it correctly on a few cars n been fine.
Would not add much scavenging if at all but could lower engine bay temperatures which could have an effect. Even, so, ceramic-coated headers would do that better.
It won't do anything but ruin your headers in the long run..it will keep under hood temps down..thats a fact. Thats about the only thing it does
EDIT: Late to the show..everyone covers what I said..lol
Running a 95 Chrysler Jeep 4.0 in lieu of the 72 AMC 258 in a 72 IH Scout II with a FAST EASY EFI 2.0 handling ignition and EFI. 100+ days of fiddling with it on the road says timing has way more effect than AFR’s. Thankfully I can adjust it all with the handheld controller!😉. Thanks for the excellent talk and graphs. I’ll be putting what I have learned to use!!
Hard to argue with Facts! Love the vids!! Nice to see the Sbc making a come back ...
You know what I think it is? I think it's that old school guys are used to idle tuning a carb/distributor car. In that scenario it feels super interactive because as you lean the idle it accelerates, as you add timing it accelerates, etc. But that's not about power, it's just about the engine running better as it gets dialed in and thus speeding up.
Thanks for this Rich. I had a 500hp 440 that I didn't think quite ran what it should. During a refresh, when degreeing the new cam I found the damper timing mark was off by six degrees. What I thought was 38 total was 32. I was thinking I cost myself a good bit of power. Your vid helps me think it was not such a big deal. Thanks again!
Thanks Richard! Nice to see confirmed in hard data what I was taught and what I've experienced.
Fundamentals like this are critical.
Excellent video Richard!!
You are the man! I can’t say enough about how much I appreciate all the work you do.
I think all the car mags people read for years and year conditioned us to think that changing timing means you need to adjust the timing as well as the other way. Thank you for clearing out the smoke.
This was a great comparison, to see the actual figures. It lines up with my experience in that a carburetor is quite forgiving, it may be a miss match at times but it will work and work well in the top end and note that a street car will be more streetable with a carby that is not too big for bottom end and mid range driveablity. The timing is an interesting one too, I have learnt through experience the engine only needs enough timing to make it happy, no more and no less. On some high comp engines running on pump octane I have had to pull the total timing back to 25deg to stop detonation and once I found that sweet spot for the fuel one particular cleveland engine was more exciting to drive than a similar spec engine with less comp and more timing. How I think about spark timing is its all about how quick that flame front moves across the top of the piston and produces the maximum pressure to push that piston back down the bore, if there is not enough timing some of that pressure is in effect wasted and too much just slows down the piston as the pressure is made too early. I like to run a soft tune on my drag car, running race fuel with 32 total so on race day I can enjoy the racing. The engine sounds sweet and happy there and makes good power and all the comments you mentioned that others say I have heard too.
Thanks for the tuning knowledge Richard.
Another great post....I'm glad to see this as my wife loves to drive my Malibu that has a 388 stroker in it and I would take 16* if timming out of it so she would stay out of the ditches..my carb buddy experts would always bring up fouling the plugs....I never hurt the plugs....be safe..
I've always wondered about the effects of timing on A/F. Great video, thanks!
Great info. Iv found that if the power valve is close to opening a idale do to big cam and stuff timing can have a part do to incresed vacum
You've quickly become my favorite channel on TH-cam.
Yes, more sbc content! I love it Richard, you're the man! Great tuning video.
Another fantastic information video! But you do a lot of power adder videos, so it would be cool to see how the timing curves might vary between nitrous, turbos, and centrifugal blowers? Like does nitrous work best with a flat timing "curve?" Does a turbo need more timing at higher rpm? Is a centrifugal blower "curve" linear or curved? Keep up the great work!
Awesome info. These vids are top notch.
Learning alot from this channel👍
Great video. In the late 90s and onwards i street tuned my efi for fuel economy, running much leaner on mild acceleration and cruise compare to factory cars which at the time would run too rich everywhere other than on closed loop. I noticed manufacturers leaned it off over the years but took them along time
I'm gonna guess here, but the newer engines have knock sensors and much more efficient combustion chambers, aluminum heads, and fuel injector placement and the quality of the fuel injector itself.
@@superkillr I would say nothing to do with engine tech, more about tuning knowledge. For example in Aust we have the Ford straight 6 from 1989 to 2002 is basically the same engine with alloy head and efi with knock however the tune was greatly refined over the years with much improvements with fuel economy. With older engines it used to come out of closed loop under very light load and very rich under light acceleration when in reality you can hold stoich in a much larger window which they did in later tunes
Also I must add the bosch ev6 multi hole injector was a tech that certainly did help fuel economy
Having tuned my own EFI car from scratch, and had the benefit of a "rich/lean" knob, where I could change the AFR's +/- 25% at a constant timing and load while driving, I can confirm that what Richard Holdner says in this video is the truth... super easy to "feel" how insensitive the engine is to small changes in AFR's at the same timing and load, but much easier to feel changes in timing for a constant AFR and load.
Hats off.... deep respect, this type of information is golden... thank you very much.
Thank you for this video. I have tried to explain this for years and you actually showed what I been preaching.💪🏻
I thought about this and a few thoughts, I went from sea level racing in seattle/bremerton to 5000 feet in albuquerque and had to take 6-10 jets out to get rid of the rich running and sheer laziness, this was on a 400ish hp 302 *basically a 1.90 valved performer rpm combo with a 650 dp* I didn't have a drag strip handy to figure out timing so i backed it down a couple degrees because I didn't know the fuel, but otherwise it ran fine it was just lazy. So I had a good idea what was going to happen with the rich a/f, the timing I wasn't expecting a lot of change maybe .5 on the a/f .3 is pretty close to my thoughts. For non carb guys that maybe a jet.. maybe 2 at most in fueling changes. What I'd like to see is dyno tuned on the dyno vrs actual changes needed for the drag strip, timing vrs jetting and mph changes *et isn't a good indicator mph is because it takes hp to make mph vrs car weight* If you have any kinda testing on that, I'd like to see it as I could never afford a dyno tune.
very valuable. I'll probably need this to limit torque to protect the transmision on a TPI
Leaned it down to 72 on a vacuum secondary 750. Went up to on the shooter! The bandage on the daily driver was great. Ran as much timing as I could get away with! It was a 306 in a foxbody Capri! The 31 shooter really helped it to catch its breath till the old 750 vacuum secondary was ready! Drove it every day! A 50cc pump and 31 shooter made it think it had a bigger carb on it!
Thank you for an informative and unbiased assessment on this subject.
I suspect many have fallen for the BS given out over the years, its good to know that guys such as your good self are out there.
This is a video a lot of Escuela Vieja dudes need to watch!
This applies to EFI and carb: volumetric efficiency from idle to max RPM will dictate both fuel and timing. Dial in the fueling with safe timing and then adjust timing for max torque (MBT). EFI lets you add timing under light loads with leaner fueling (lean mixture burns slower, needs more timing) and increase MPG. WOT on a well tuned EFI setup with very efficient heads (chamber) typically only wants 18-22*
You don’t adjust fuel to accommodate timing changes- if anything the reverse is true, at least in EFI for most efficient burn/ MBT at a given (or all) RPM.
I'm no engine guru by any means but I could not see a relationship between Ignition Timing and AF. Now advancing / retarding the cam I could see a little because the signal would change a little.
Great video, I learn a lot here.
Advancing/retarding cam shifts the power band down / up so yes fueling will change slightly as the ve changes
You need to wear a cape and mask and introduce yourself as Captain horsepower !!! Or Major torque !!! Another great video Sir and all the best to you and yours.
Damn Richard way to knock it outa the park
Thankyou
No more no than 5 tenth Im thinking
Great as always. As a young man I always heard 14.7:1 is the optimal A/F ratio. I always thought 12:1 was too rich. Not that we measured this scientifically or anything. We measured by ET slip. What about those Chrysler lean burn motors? I heard they ran in the 16:1 range. Of course, they were pitiful dogs for motors. I learned the timing thing early. I put a 340 4 BBL on my 318 Dart, set the timing by ear and went cruising that night. Did okay and even beat another 340. The next day I put the light on it only to find out I was 15 degrees too low. It was a tire fryer after that.
the 14.7:1 (and 16) number is for idle and cruise
So glad you did this video. It’s almost daily that I get asked to find people 30+ HP on a car or 10+ HP on a bike that’s NA with just a tune. Now going from stock ecu programs to a custom tune can indeed net that realm of power gains, but if your vehicle is already tuned and you just changed a muffler section or changed intake filters that minute 1/2 degree or so of timing or few tenths AFR I adjust in either direction is not going to break the dyno with massive power gains lol.
Side note: I would like to see this test done on a boosted application and would be especially curious of the timing aspect and it’s effects. I say this because I really can pick up significant power on say a turbo setup with small incremental timing changes in most cases, but it would make sense to magnify NA gains on a boosted setup. I would just be curious to see if the changes follow suit to doing it NA just by way of larger gains.
I’d love to see these AF charts in Lambda. I switched to lambda when I went to e85 and it made life easier on the gm stuff.. good stuff as always Richard!
A billet metering block with multiple bleeds in fuel well can trim the curve somewhat with rpm , not efi but there is a something there . But fantastic information , thanks again .
While I'm not gonna argue that, can you imagine the number of top carb tuners Richard has been exposed to over the years? Do you think they don't know about billet this and new sensational carb product that?
This is great stuff Richard, keep it up! Very educational.
So my dad was right back in the day, "90% of all carb problems are in the ignition."
Came over here from UTG. Great information on true tuning tips. I like that shirt!
Basic question
Basic car
Hypothetical old carb'd...
"If I could" what would be "ideal":
1)idle AFR
2)acceleration AFR
3)cruise AFR
4)WOT AFR
Thanks guys 🙏
Depends on the engine combination.
For fun, 14.7, 12.6, 13.6-8, 12.6.
There's too many variables to define an absolute AFR. There are some generalizations that work ok but even still, every engine is different.
@@OxBlitzkriegxO
Generalizations are ok for now. Thanks. I know I had read this somewhere a long time ago.
I appreciate the response.
Wow, great information. Thanks for all your work.
Timing was my big problem for lack of performance during RMRW. The mechanical advance wouldn't advance more than 8 degrees even at more than 4000 rpm. I had to run the initial timing at near 30 degrees in order to get 36 degrees total. My 1/4 mile times shown I was down near 100 hp.
Thanks for this testing this! I've been curious about the timing/AF relationship for a while.
Great information!
11 degrees? I'd think that to be a very hot engine to walk around when it was running, glowing headers and all that. Good times.
Something worth mentioning is that the jet sizes on a Holley may seem like the hole diameter difference is small but it can make a big difference because the area is calculated by pi*R^2. As an example going from a 74 jet to a 79 jet is an area increase of about 20%. In this case it means going from a 74 jet to a 100 jet is about a 60% increase in fuel!
Vizard said to get the timing close, adjust the AFR then dial in the timing in his Holley book because there would be minimal change. Definitely validated in this dyno testing.
Were you even within the range of the WB on those super rich tests? Not sure where the limit hits on a higher end WB but on an LSU4.2 I believe you'd have been out of range rich e.g. it could have been even richer than it showed up as. Based on my guestimates I'd think you'd be nearer to 8:1 if not dipping into the 7s.
RE:changing part of the RPM band on the carburetor. Obviously you're not going to change say a 100 or 1000 RPM band but I would think you could alter the PVCRs, the HSABs and the Emuslifiers to influence the higher RPM power. Typically that is a big proportion of the stuff that's done to a blow through carb e.g. reduction of the HSAB, increase the PVCR and decreasing or elimination of the emulsification. Well that and vent tube extensions in a lot of cases.
On a QJ that curve would be influenced by the taper rate of the metering rods. I'd think it to be very noticeable in some of the smog era rods compared to the performance era stuff.
yes
thank you,valuable information 🎉😊
Keep em coming Richard
Great video Richard - this kinda explained why the First Gen Z/28s came with a Holley that was almost identical to the Holley on the L- 78 396 cars of the same era
Hey Richard, glad to see another video, you always make such great content. If there’s one thing I could request is to see a 5.4 2valve ford from a junkyard with a few bolt ons and boost, I know they aren’t the greatest engines for power, but they are super common and I havent seen much content about them ever.. thanks!
same as the 2V 4.6L-just more
If the subject was about how these changes effect emissions and fuel mileage there would probably be a much more significant difference in their values , and perhaps that`s where some confusion exists, but then you have to start talking about regulations and five gas analyzers and that would just take a lot of the fun out of it.
Fuel injection technology has come a long way and we can probably thank regulators and engineers for that because now days you can actually talk about high performance and high efficiency in the same conversation. Thanks for another great video.
Could you show a set of plugs from a 12.5- 13.0 a/f setup? I think people might be shocked at what they look like.
that's really a detonation thing
I think you may have just came up with another video idea, Richard. Would love to hear your opinion on it.
True if you can hear it. Open header racecars dont make that real easy, unless it's real bad. By that point you have probably hurt the engine. Plugs on the other hand can tell you, if you know what to look for. I.E.- small shiny dots on the plug, is ONE indication of detention.
Excellent video! One thing I've noticed in my car WRT timing, We run 40 degrees in first gear, 37 in second and 34 in third gear and the car does ET better.
Cool thank you for this Richard! Learned a lot. I thought messing with the A/F ratio would affect the engine to a larger degree. I have no experience tuning tho unless u count changing parameters on my lil pocket plug in tuner 🤣
Richard - this video is so valuable in terms of information and education. Thank you so much! I have always wondered how much timing changes affect air fuel ratios, and now I know! One more thing Richard - I love your tests you do with large boost numbers, can you do some testing with big big nitrous? Like 500-600hp worth of direct port nitrous? I’d love to see the low amounts of ignition timing used with that much nitrous. SBC, BBC or LS I’m sure us nitrous guys will love it!
that's a lot of nitrous
This is a REALLY GOOD informative lesson.. thanks for giving some clarity 2 something I've wondered about! This is the sort of stuff I love!
Great test. Great info.
I've had engines I've built be extremely sensitive to timing like 40-50hp going from 32-36* and other engines that almost dont gain hardly anything doing the same change, it really depends on the combination, and that's why imho you always want to dyno tune a new engine because everyone is different!
True. Have you had the chance to evaluate E85 in some of your combos?
@@dennisrobinson8008 no, E85 isn’t common at the pump up here the the PNW and I mainly do NA engine builds so I haven’t played with it much but I’d like to!
@@DSRE535 I can imagine! On a 400-500HP N/A engine they are getting 5-10% gain with E85 and adjusting the timing 2-5 degrees. Plus it's a more forgiving fuel for detonation. If you were going to be ALL E85 all times, you could literally run 14-15:1 on the street N/A, and 12:1 boosted with E85.
@@dennisrobinson8008 Oh yeah I know I wish it was at the pump I’d be running everything at 13.00:1 lol
@@DSRE535 Damn! I had a thought too, so there is a loss in MPG of about 20-30% over gas. I was curious if going up in the compression ratio can get over this somewhat by making the engine more efficient? Each pt of CR is worth 4% on gas, so going from 10:1 to 13:1 is 12% gain in torque across the board.
My comment is 455. ☺ Thank YOU, Richard. U may have saved my engine. I'm in agreement: give up some horses to ride another day. I'm sending this to some buddies. 👍
What about flipping the air filter lid upside down?!!! 🤣
Waaaaooooohhhh
Thats more.. VROOM VROOOOMS!!
Shhhhh dont share that 100hp free mod LoL
Dont forget about a flowmaster sticker
Chwooooop
Would the A/F change on the major timing sweep just be a reflection of unburnt fuel therefore throwing off an accurate reading of what is going on in the combustion chamber?
That's what I wondered
Awesome test !!!!
Very educational video, Richard! Do you ever do part-throttle power pulls to see what the A/F is under conditions more like regular street daily driver conditions? Below certain torque levels, A/F can be right at 14.5 for good fuel economy. Then can the carb be tuned to get 12.5 at WOT to keep the power and detonation margin?
desired AF is leaner under cruise