I tune a lot of Folk's carbs at different car events, and this one methodology in initial adjustments cleans up almost everybody's issues right from the GET GO as it allows the dynamics of the carb circuits to actually work as they were designed to - no chasing tunes or bandaiding misadjustments with misadjustments elsewhere ending in disappointing performance. If i can do this, anyone can !!!! Also, everyone who wants to perfect the carb tune needs to run one of these wideband "Air Fuel Ratio" gauges!!! AEM Wideband Gauge Kit - amzn.to/2wlxxL4 No Welding Exhaust Bung - amzn.to/2BCi4MO
It may be a lot to ask but because you all ready have a baseline using a ported vacuum source would you be willing to switch to manifold vacuum and retune and drive it for a bit ? It would be interesting to see back to back testing in real daily driving conditions to compare mileage and performance. I know it would basically only pertain to your setup but I think it would make and interesting video if it's not to much trouble. Thanks for taking the time and doing the work on these videos they are very helpful and greatly appreciated.
I have a lag response when the butterflies close after a heavy acceleration, low speeds.... 5.0 H.O. - 600 Holley w/vac secondaries. Any thoughts on what to check? Thanks.
Installed an AME on both our 1986 C10 and my VW engine run test stand no issues with welding in the bung. Work in Marshalltown are your very far from there ??
I was doing way too much guess work with my fast idle screw, curb idle, timing, etc... Getting under the carb to see my slots made a world of difference and really improved throttle feel. Great info!
Man I wish you were closer! I’ve been banging my head against the wall with this Holley 4160 carb. Sputtering at between 1/4 throttle and 3/4 throttle. I’ve replaced the accelerator pump diaphragm, set to .015 at full throttle, set the transfer slots like this, deep cleaned checked for vacuum leaks, tuned and tuned again, new plugs, wires, cap, rotor, coil, ballast resistor. Think it’s just time for a new carb
Same here but with my Edelbrock. I think I have found my issue to be a too heavy mechanical advance spring. The only way to get 32 total degrees at 2500 is to set my initial timing at 28. I only get more advance if I run it over 5000. As soon as my springs arrive I can test more
Hey now!! Watch those "old timer" comments. Lol I'm sure I'm not the only grey beard that enjoys your channel. You really do an incredible job of outlining the how and why of tuning.
Hey Thanks for all carb tuning videos. I have a 850 holley. When I go to install it I'll most definitely go back and watch the videos. Thanks again and have a good one!
You seem very bright and knowledgeable but some people don’t understand what you mean by squaring the carburetor you should demonstrate the processes and that would be very helpful to those that really don’t understand but would like to tryout your expertise
I understood him to say squaring the transfer slots to where only a small looking square of the slot is exposed but my question is how do you make that adjustment? And would this be true for a ‘70 Oldsmobile Quadrajet?
I just set up my 750 Holley just like you described. What a difference. I used to get a lean misfire pop though the carb when hot and other driveability issues. So smooth now off idle. Idle is smoother. I thought it was the accelerator pump setting. Glad I watched this. Thank you
Hey brother, I appreciate all your videos. I've been a fan for years and you've taught me personally so much over time. God Bless You and Glad Bless America and God Bless My Fords.
Most people don't really know the difference between ported and non-ported vacuum. I have run carbs and EFI and tuned them both. For those who do not know there is a special vacuum port on your carburetor that you would typically hook your vacuum line to from your vacuum advance distributor, and that is the ported vacuum. The ported vacuum port has zero vacuum at idle aka no vacuum advance at idle. Now if your hook your vacuum advance distributor up to any other vacuum port on your manifold or carb it will have vacuum at idle and you will get 10-15 degrees of advance on top of what you set your initial advance too with your timing light. So 10 degrees with your timing light plus 10 degrees from the vacuum advance will give you 20 degrees of advance at idle. Now why would you want so much timing at idle? Leaner air fuel mixtures at part throttle down the highway and at idle like more timing. There is less fuel in the cylinder and takes longer for the fuel to burn which is why more advance is beneficial at idle and cruise. It will help to lower your exhaust temps, engine temps, ect at idle by using manifold vacuum on your distributor. Most people also think that high idle advance is only for radical cams which is not true. I have run 20-25 degrees of idle advance on carbs/efi with no issues on stock 70s era engines. 200HP boat anchors in other words. As time goes on there is less and less knowledgeable people about how this old stuff works. Keep the videos coming thunderhead289 otherwise working on older vehicles will become a lost art.
i use manifold vacuum if the engine needs over 12* of timing to idel. most 1970s stuff needs 16-25* of timing so manifold vacuum is the way to go. i have seen how a 70 engin with 12* wold get vary hot switch to manifold it dropped the water temp 20 degrees. used less gas to. i like a fast timing curve all in at 3500 rmp 20 centrifical with a base timing of 2-5* for a totel of 22-25* so 87 gas can be used. this gives a total timing at cruse of around 40*.
By simply reading and trying things and using wideband o2s and vacuum gauges to monitor everything. Honestly I’m just an average dude who just has an eye for detail
Thanks great info, I appreciate all your videos. I am almost done rebuilding my 65 289. You have helped me degree cam ,set up Valve train now soon carb setup, much appreciated!
I saw a video where the transfer slot "square" was set without removing the carb by putting a vacuum gauge to ported vacuum and turning throttle screw out ( closing the throttle plates ) until the reading on the gauge went to zero. It was made by Junkyard Digs, very interesting explanation. I'm going to remove my carb, set the square by sight ( keeping track of the # of turns from closed to get there) then compare it to the gauge method. Thanks for the video.
This is an older video of mine - I taught him the ported vacuum thing that works 85 percent of the time depending on the carb manufacturing. If you have vacuum on the ported port though - it is in fact too much curb idle. You need to advance initial timing and reduce curb idle screw in that case.
@@ThunderHead289 You are absolutely correct on that. Keep up the great videos. I sure wish someone would undertake the task to quantitatively tune one engine( stock V8 with mild or stock cam say) with Ported vacuum and then tune same engine with manifold vacuum and and at the same time use and describe the adjustable vacuum advance. There is very little on the effects of and tuning the vacuum advance can. It's a tall order but I've not seen that on TH-cam.
Luke, you are awesome. My 78 chevy has been a fun project. After dropping in this sb i just finished rebuilding, the final tuning was at a halt until this video. Thanks man. Hope that good ol ford stays that way for you.
I called Holley and found out that idle air adjust was on the SECONDARIES! After setting the square on the primary transfer slots, it would not idle. There is a hidden secondary throttle plate adjustment that allows additional air for idle. Works great, NO hesitation coming off idle. (1973 Dodge 360 Holley 4160 carb)
Great video. When I bought my truck I adjusted a few obviously wrong things and each one made things worse due to a series of rigs and bandaids that were working in perfect harmony. I ended up saying screw it and redoing the whole top end. It took a lot of work and time but I learned a ton about tuning. I can't say for sure because I changed so much at once but I have a feeling getting the transfer slots right was one of the biggest improvements.
I love these tuning videos. They have helped me so much getting the Webber on my Mazda b2200 running decent. Just took a long cruise to Oklahoma and back to Nebraska last weekend spinning almost 4K the whole way I got constant mid to upper 20s mpg the whole trip
Yes but long duration cams with valve overlap (increasingly used on the street) benefit from a rich idle mixture and high throttle setting, which has given the use a ported advance relevance beyond the emissions debate@@mrblanche
If you hook your vacuum advance to the manifold the engine will idle faster than it will on ported vacuum. To correct this, people close the throttle and this put the transfer slot into a no-flow dead zone and creates a bog off the bottom. That is why some cars run better on ported vacuum. (ANd yes this was used before emission control but it was then abused during admission control years and hence the bad reputation.)
Luke, appreciate the clarity of your presentation. At 6:17 in the video you mention that when you set your throttle to show the "square" of the transfer slot you get a "little vacuum signal at idle." Can you tell me if the vacuum signal is measureable on a vacuum gauge. Currently I am getting about 4HG mercury in gear at 550 RPM. I have timing set at 14 Degrees (I have a comp cam 268 and the car has only 8.5 compression, and yes I know I have too much cam for the compression). The car runs great at full throttle and cruise, but does not get very good gas mileage. Not using a can, and plan to do so after resetting timing curve.
Very information dense. Love it. I now know how much I need to know. Off to do more fun research before touching the carb on my only ride. Thanks a lot!
Luke, I have a question.... I understand about adjusting the throttle primary throttle plates to reveal the "square" of the transfer slots. My question is after the Holley is bolted on the manifold and is ready for idle circuit tuning chain of events so to speak. 1. Turn idle mixture needle screws clockwise until the just bottom out. Then counter clockwise 1.5 turns for each screw. 2. Cap the ported vacuum port for the distributor canister., Connect timing light 3. Start the engine and keep the engine running by opening the throttle by hand to warm up the engine. 4. To set desired idle speed of 750 RPM, rotate the distributor until tach reads 750 RPM. 5. This is where I need help...Using a vacuum gauge connected to full manifold vacuum, adjust idle mixture screws 1/4 turn each until peak manifold vacuum is achieved. NOW... the idle RPM has increased when peak manifold vacuum is achieved. Do I rotate the distributor again to decrease the RPM's back to 750 RPM's or... do I adjust the throttle position screw??? I would think the distributor should be adjusted again to 750 RPM. But I'm not sure BTW this is a 4165 Holley Spreadbore List 6211-1 800CFM on a 427 Chevy
Michael....that is my exact question too. Luke is advocating that he wants to keep the transfer slot square for a range of good reasons, which is about 20 thou ...a square shape, and he is using rotation of the distributor to set rpm so he can maintain that square shape on transfer slot.....so I think to maintain that square shape after adjusting the idle mixture screws for max vacuum, it seems to make sense to me to rotate the distributor once again to adjust rpm back to desired level......but this is never mentioned by Luke. I think your logic is right Michael, otherwise the transfer slot shape at idle would get screwed up by adjusting the idle speed screw to reset the rpms after adjusting idle mixture screws.
One other thing. The advantage of rotating the distributor vs moving the idle speed screw is that you don’t need to readjust the accelerator pump lever arm from your initial setting. Most people forget that if you move the idle speed screw you must readjust the accelerator pump lever arm to get its gap to 15 thou.
Ooh I just thought of another thing. If you advance the base timing too much at idle (by playing with the rotation of the distributor to get desired rpms), will that result in pinging at higher revs caused from total timing (base plus mechanical and vacuum advance) being too much when the engine revs at an “all-in max timing” which may happen around 3000 rpm? I guess some experimentation is required. I just hate pinging because I want to protect the engine from any potential damage
Holy shit, can't believe a couple of these commenters. Can't win 'em all I guess. Appreciate your insights here. Always planned on going FI because gadgets, but the more I dig into your series it makes me reconsider.
You should see some of the ignorance that I decided to remove. Followed by the “well on such and such channel, they said this” - I don’t like to make war between channels, but the bad tech presented by large channels out there is appalling
Folks who say ported is designed for emissions are just wrong. So some engineer (unverified) made a claim about it that everyone has run with for years. I'm also an engineer, I also work with engineers - not all engineers are smart nor do they know what they are talking about.
@@ThunderHead289 I would say David Vizard knows what he’s talking about. That’s exactly what he says. I’ve argued with many on the subject, thought long and hard about it, and nobody has convinced me otherwise.
@@ThunderHead289 Ported vacuum is to keep NOx emissions under control at idle. That's it. It is more desirable to run manifold vacuum advance. One big advantage is your engine will run cooler at idle. If you have issues with idle speed and full manifold vacuum advance, you may need to find a mechanism to limit the total amount of vacuum advance.
Hello Luke, I’m a big fan of your tech tips, - your way of explaining things suits my learning curve perfectly. I’m not sure if you take requests, but if you’re looking for ideas - may I suggest a run through of steering box adjustment. I’ve just stumbled through this myself, and there’s not a lot out there that I could find anyway.
As always I love all the info you and JYD have on your sites. Couple of comments. 1. since you daily this truck with a late model 302 and the O/D trans. with the factory 3.70 gears what kind of performance do you get. MPG, driveability, etc. 2. You guys need to get some of your stuff on Mr. Regulars site. Maybe get him to bring the Falcon out here to Iowa or he and the Fuel Injection sucks guys can bring the LS Winnebago home to Forrest City, and then he can review this truck. LOL!
Check this out , I have flipped over a 750 holley and a demon to check were the transfer slot. Comes into perfect square is right around 1 full turn from just making contact with the throttle lever , so if your not taking carb off that's a very good starting point
Luke....love your videos and have learned an enormous amount. Thank you so much. With respect to transfer slots, I need to unbolt my Holley 4160 and flip it over to inspect the size of the transfer slot. Is there anything I need to be careful of when I do that....obviously spilling fuel....but can I damage anything by flipping it over? I am going to check my slots because I appear to be showing 3 inches of vacuum from the Ported slot, and you said in another video, that might be due to the transfer slots not being set properly....as the ported vacuum reading should be zero at idle. Many thanks
Im illiterate on the subject of carbs as a lot of folks are, could you do a vid showing where / what everything runs to when talking about time, vacuum fuel etc. thanks
Thanks for all the helpful tips you've lent to all of us over the years. All of your advice has always been helpful.Question....Would your O2 gauge set up work with an older and richer running flat tappet motor?
first of all, thanks for your continued efforts on these videos and sharing your experience and knowledge with us out here. i know you have a video or two discussing the differences between running manifold vs. ported vacuum from a debated perspective....but is there any hope for an actual "how-to" with actual footage of each step to include adjusting the canister, etc? i.e. if you choose to run ported vacuum or manifold, set you initial timing like this: (insert video link here) but here are the specific differences, and i'll walk you thru why they are so important. Just a thought. in any case...thanks again, and looking forward to more content! Cheers!
Blake, you know what - maybe I will shot a little intro video to a series like that. Iv been meaning to for a long time - tomorrow might as well be the day
@@ThunderHead289 i think there are plenty of folks that want to at least try to run manifold vacuum, but hesitate cause they dont want to screw up their rides....myself included. Your videos are always very clear and comprehensive. Thanks for responding so quickly! If you ever make it out to western Montana, the beer is on me. Cheers!
Since 1970 , ive used the two man ,power braking method to set my carbs --- and my timing ! You can also put the bumper against the tree , but its not safe at my age ,plus you dont have the vacuum draw on the brakes .😂🤣 Great to see old skool young guys teaching others the lost ways . Plus im a big fan of eec ignition ,points are pointless imo . Many are lost as far as grommet color coding for brain boxes and distributer plugs 😵 but that's a whole nother vidja . Thanks buddy love your content as always keep scrapping the motorcraft toilet bowls. 😨😂
Your bumper against a tree reminds me of my college roommate in South Dakota. We lived in a small house with an inclined driveway. In the thick of winter he enters the house and asks if I would help him get his car up the driveway. We walk out and find his 73 Vega, tires spinning in the snow, trying to inch its way toward the house. I think this may have been a very early version of an autonomous vehicle.
I can, I have a very simple concept there also - really this stuff isn’t as hard as everyone makes it out to be. All the bad info and misinformation out there has made it seem difficult.
In your opinion, is a 600CFM carb a good fit for a 390FE? The motor is old, but still runs good providing about 17 to 18 inches vacuum at idle and is pretty much stock and had the intake changed to a Ford Police Interceptor aluminum unit way before I got the car. Its been having some issues lately with the Edelbrock Performer 750CFM it has. A friend of mine gave me a Holley 4180 600CFM to rebuild and try out. This carb is a factory Ford original unit from a mid-eighties F250 (Mustang 5.0 liter in the mid-eighties used the same) and has huge primaries, vacuum secondaries, electric choke and is an emissions carb having extra vent tubes coming from the float bowls. I was going to rebuild it and give it a shot, just want to get your take on it. Thanks for the vids.
I like your videos, I got an old Q-jet I bought and got the overhaul kit. Now it works really good, and I didn't have to do much tweaking either. But I will get the wideband lambda to check how well I did and do fine-tuning. And I like that song at the end of your video, what's it called?
Q-jets always run good on near stock engines.I doubt that buying a wideband in your case would be money well spent. They use metering rods which to me are more mysterious than simple jets. One issue they do have which will greatly affect driveability is wear between the throttle shafts and the main body of the carb. If you try to wiggle the shaft up and down you should not feel any play. If you do they are worn and prone to air leakage.
Would you mind doing some motorcraft tuning videos? Mainly the 2150? Only reason I ask is because thats what I have a normally on smaller engines (V6) still have the old 2100 or 2150 carb. Ive learned a lot on my own but you are WAY MORE knowledgeable about carbs than me. Plus, inform people who dont know as much.
What do you do when you square off the idle slot and it idles low or not idle at all? Have a problem where we have a brand new edelbrock carb on a 390 fe and we made sure with the motor at TDC ( compression stroke of course) it was right inline with #1 plug. Go to fire it and she won't idle at all, tried advance it as far as it go then it will kinda idle but at like 550rpm and the timing light shows about 49 degrees advance ( vacuum advance unhook). So not sure what's going on. Also I did notice if I put the timing back where it was ( roughly 14 degrees ) and made sure to back off the idle screw to where it was ( turned it up to get it to idle ) I could hold the secondary open a little and she would idle low but would idle without messing with timing. Any ideas?
I've got a 1967 Ford Econoline van. It's got a straight six 240 CID with a 1 barrel carburetor. Do you have any advice on whether I should still use the original oil bath air cleaner or change over to some kind of aftermarket air cleaner? Thanks a lot, Tom
My 67 Bronco, with the original 289, used to vapor lock all the time. I added the wood style spacer still did it. Added a fuel cooler. What the heck is a fuel cooler you may ask... Its an old power steering cooler from a Ford explorer. Yep... See... My fuel was hot coming out of the fuel pump. My fuel pump is heating the fuel up. Sounds nuts I know, but it was. Ill upgrade to electric when I go EFI later.
I have a edlebrock 1406 on my 302 with a small .456 lift cam. I jetted it to .100 primary jets and .98 secondary jets. My fuel is pretty close. I am using a wide wideband gauge. The issue im having is fuel leaking out of the bowls. Its hard to start cold or hot. It used to only be hard to start when it was warm.
I was watching a video from webber carburetors,And I thought that the guy who was explaining how to tune them said it better than anyone else had in all my 55 years! That screw on the side of a carburetor that everyone of us has turned the crap out of when we were rookies! Is not for tuning the carburetor. He said all that should ever be turned would be just enough to keep the throttle plates from connecting with the side of the throttle bore and causing a depression if the throttle was to be let go of and snapped back closed! Absolutely no tuning benefits beyond that! Once I heard it explained like that I wondered why in the hell didn't someone tell me that years ago?1🤔
Hey just out of curiosity. I have a dumb question. I've been playing around with the timing on my chevy 350 in my 82 k10. Its bored .60, has headers, mild cam (comp 280H), not a ton of lift or duration, it just idles sorta lumpy. Double hump heads with 1.92 intake valves. I've had my timing set at 8 btdc, I'm trying 12 now. Do you think ita needs more? People have told me 8 is plenty, which I highly doubt. Some people have told me 20, which seems like too much. I'm not interested in the "all in" timing right now because it's a slow 4x4. I'll mess with that later. Just wanted to pick your brain. Thank you in advance.
I switch out the ignition module in the distributor of my 350 5.7 i got spark but it would start it back fired. Also no matter how many times i turn the needle and seat i cannot get fuel into the front sight bowl
Wow I didn't expect to see so much salt in the comment section 😅🇺🇸 I'm in the middle of your process. My carb is adjusted correctly and I'm putting in timing to the engine. I'm at 18 degrees initial now and I need another 200 rpm to make the idle smoother/better vacuum signal. How do you know if you've added enough initial timing and if you need to start modding the carb (air bleeds/holes in butterflies)? I have a large cam with loads of overlap. Carb is crispy otherwise. Thanks for the vidoes 🤙
TheSaxon25 this is where it can get tricky to tune via messages because I don’t know the build or your dynamic compression scenario - a lot of times guys overcam a bit and have low cylinder pressure at idle dictating the need for more timing. The one thing I can say is that everything is a balance, and you may be able to get more vacuum/higher idle based on how rich your mix screws are set - I’d look here next, and allow yourself a 1/2 more turn from the squared off position with a big cam. Generally the square is for 800 or less - as idle rpm increases, this needs to be opened up a bit to compensate. But if you can help it, minimize your throttle opening input 👍
@@ThunderHead289 thanks for the reply! We built the engine around the cam and heads so I know the parts are congruent or at least theoretically should be okay together. Part of the reason I am hesitant to raise the timing is because the MSD pro billet distributor I have doesn't allow for an advance stop bushing at 36° if I go over the 18° initial. 😅😅 I just ordered a wideband. I think that will let me cheat enough to figure it out 🍻🍻🍻🍻
@@TheSaxon25 How much vacuum do you have at idle? If your idle is not super choppy due to cam overlap you can use direct manifold vacuum advance which may get you the 200 rpm you need.
@@65sohc hey dude. I have 6-7". The car has a lot of chop. Isky z-35 cam. Steady fuel pressure, floats are perfect, transfer slot is slightly over square, no vacuum leaks, four corner idle set at 2.5 turns out, speed demon 750 VS (gen1), probillet msd distributor (no vacuum advance), 6al msd box. I'll find a fix that doesn't involve switching to fuel injection 😂😂😥🍻
@@TheSaxon25 Yeh. That's sounds like a pretty healthy cam with too little vacuum to run straight manifold vacuum advance even if your distributor had it. Even though you're at 18 degrees initial you can still try creeping it higher. The only limiting factor is if it becomes hard for the starter to crank the engine over.
Any way to popstion primaru transfer slot correctly wirh out removing the carb. "Vacuum at idle"' does this imply that the ported vacuum connection will show some vacuum? Could one use the the vacuum signal at the ported vacuum connection to set the amount of transfer slot exposure? Say, adjust idle screw untill vacuum apwears at Ported connection then back it off until it just dissapears?
I just had my mechanic install a brand new stock 2150 carb on my 77 Ford with a 400. It seemed to run pretty good until it started to vapour lock So I did the old heat shield around the fuel line and clothesline pins method. It hasn’t vapour locked yet but I haven’t really been driving it much either but now it seems to be blowing Black smoke??? I’ve been running shell V power in it and can’t understand why it’s blowing black? I don’t know if it’s a blown power valve or if it’s trying to vapour lock?
Hello Thunderhead 289, I just purchased a 62 Chevy C-10 it has a 327 motor bored out to a 355 with a Edlebrock Carburetor. It was running a little ruff at the idle when I test drove it and thought this guy just doesn’t know how to time the truck so I bought it. I noticed the vacuum advanced hose wasn’t hooked up and thought that was weird. I set the timing on the brand New Carb and thought I was good. When I drive it the idle jumps after I set it. It does t want to stay idled at stop lights and I have to keep it going giving it gas. I set the timing and went to 6, 8 everything and the idle still jumps. Any ideas? Ray
I could use your help identifying a particular engine in a 66 Thunderbird. I have lots of reason to believe it is not the standard motor. I'm more of a Chevy guy so any help would be appreciated.
Hello Thunderhead, My name is Mat or modiemat1978. I picked up an old 1980 Chevy Camper Special about a year and a half ago and have been chipping away at it. When the budget allows. I am having trouble getting it to run smooth consistently. Three times the it seems like my float adjustment has moved all by itself. I have watched all your videos and I think I have the order of operation for initial carb set up. But, I have some specific questions and info for you to ponder. If possible can you help me? Sorry its so late I live in on the west coast.
I'm a Ford guy, like you, but this is about the Summit carb in particular. Have you had issues with the threads being too loose with the idle mixture screws? On my 600 cfm vacuum sec. the slop is so bad that it creates a vacuum leak, the screws are extremely loose. Have you run across this issue? Do you have a fix? I've thought of a couple, but I'd like your opinion. Good luck on "ol'man 65" It reminds me of the 69 Ford Custom 2dr post that I had years ago. It came with a 429 from the factory; it was a special order police package car from a small coastal town in Georgia. It ran and handled really great; unfortunately body rust was its nemesis. Thanks for sharing your knowledge and videos.
@@65sohc That was a good idea that I actually tried; I appreciate your input. It works, but I'm looking to make a better fix and was wondering if anyone else had this problem. I'm considering the possibility of installing heli-coils if I can find the right thread size. I know that these particular mixture screws have a different thread size than the Holley 4150/4160. They're bigger in diameter, but they share the same size as the Holley 4010. They aren't available separately either so if you mess one up in the process, you're on your own. Maybe I can achieve a fix by using one or the other, I'll have to see. I think that the problem was because this particular carb was one of the early castings and as luck would have it, I was awarded the challenge of fixing a defective piece. I really should have returned the damned thing. The real reason that I bought it was because it was an updated version of the Holley 4010, which I liked the design, especially for the annular boosters.
@@65sohc That's what I was thinking, too. I have seen some pretty small sizes, but I haven't researched that particular thread size yet. Another option is good old JB weld. The original formula is pretty tough and chemical resistant. It should be able to hold a thread. We shall see.
@@williamcharles9480 I hadn't thought about that. Project Farm has some great videos comparing the various formulations of JB Weld to similar products and it is always near the top.
From the underside of the carb, with the throttle closed, only a square of the transfer slot is showing. From this point, you have about a half turn of the curb idle screw before it starts causing issues and drawing too much from other circuits. If you need more throttle, try advancing the initial timing instead
Hey Luke. Always enjoy your videos. Very informative. Just one question though. If I make my transfer slots square my engine does idle too low as you mentioned. However I don’t have the luxury of being able to adjust my timing to be able to bring the rpm up. If I set my initial timing any higher than 8 degrees I get pinging under load. Any other suggestions how I can get around this issue?
I have a demon 625 and if I make the transfer slots that size it opens the two barrels more. Is it possible that the two metal flaps, I don’t know the name were installed backwards? Any help is greatly appreciated.
mine keeps idiling rough whats the base line for Idle screw. i know the fuel mixture for holleys 1.5 turns but not sure about idle and car some times runs on after shut off.
To where on the underside of the carb, the transfer slot exposure is at a square vs more exposure would be a rectangular shape as you expose more and more of the slot
My truck has no power steering or brakes it drives horrible lol I guess what I am asking is do you have any ideas how to improve the steering and breaking on a none power steering or brake 1971 f100?
I just bought a edelbrock 2x4 intake and carburetors. I have a 57 chevy 283 small block. In 55 56 and 57 they run two carter afb carburetors. How do I tune thus set up to make it work on my car?
Hi bro got a ? I have a sbc with a 292 cam dart pro 1 iron heads I got time set on 12° and 750 summit carburetor . It starts and ideals good but will not take gas and backfire through the carb when I try to Rev it up in park .put in gear and try and get it up on the stall (3500) it black smoke like it's flooding and pops and cracks will not evon turn the tire over. I have watch your carb videos and vacuum advance video im running out of ideals. He dis with vacuum advance
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I tune a lot of Folk's carbs at different car events, and this one methodology in initial adjustments cleans up almost everybody's issues right from the GET GO as it allows the dynamics of the carb circuits to actually work as they were designed to - no chasing tunes or bandaiding misadjustments with misadjustments elsewhere ending in disappointing performance.
If i can do this, anyone can !!!!
Also, everyone who wants to perfect the carb tune needs to run one of these wideband "Air Fuel Ratio" gauges!!!
AEM Wideband Gauge Kit - amzn.to/2wlxxL4
No Welding Exhaust Bung - amzn.to/2BCi4MO
thunderhead289
It may be a lot to ask but because you all ready have a baseline using a ported vacuum source would you be willing to switch to manifold vacuum and retune and drive it for a bit ? It would be interesting to see back to back testing in real daily driving conditions to compare mileage and performance. I know it would basically only pertain to your setup but I think it would make and interesting video if it's not to much trouble. Thanks for taking the time and doing the work on these videos they are very helpful and greatly appreciated.
I have a lag response when the butterflies close after a heavy acceleration, low speeds.... 5.0 H.O. - 600 Holley w/vac secondaries.
Any thoughts on what to check?
Thanks.
Installed an AME on both our 1986 C10 and my VW engine run test stand no issues with welding in the bung. Work in Marshalltown are your very far from there ??
ThunderHead289 I’d like to know how to adjust the dual vacuum distributor on my 65 289.. little frustrating at times trying to get it dialed in
I was doing way too much guess work with my fast idle screw, curb idle, timing, etc... Getting under the carb to see my slots made a world of difference and really improved throttle feel. Great info!
This is by far the best carb tuning video I have seen to date. No b.s. just straight facts and info. Thank you sir!! I love the truck!
Man I wish you were closer! I’ve been banging my head against the wall with this Holley 4160 carb. Sputtering at between 1/4 throttle and 3/4 throttle. I’ve replaced the accelerator pump diaphragm, set to .015 at full throttle, set the transfer slots like this, deep cleaned checked for vacuum leaks, tuned and tuned again, new plugs, wires, cap, rotor, coil, ballast resistor. Think it’s just time for a new carb
Same here but with my Edelbrock. I think I have found my issue to be a too heavy mechanical advance spring. The only way to get 32 total degrees at 2500 is to set my initial timing at 28. I only get more advance if I run it over 5000. As soon as my springs arrive I can test more
Thanks Luke.... your carb tuning is always spot on... definitely a lost art. I sure enjoy seeing the '65 and the F100.
Never mind I was looking at the carb from the inside out,I took it apart no wonder it looked reversed. Thank you for the video.
Hey now!! Watch those "old timer" comments. Lol
I'm sure I'm not the only grey beard that enjoys your channel. You really do an incredible job of outlining the how and why of tuning.
Hey Thanks for all carb tuning videos. I have a 850 holley. When I go to install it I'll most definitely go back and watch the videos. Thanks again and have a good one!
Thanks for a friendly comment!!!!
You seem very bright and knowledgeable but some people don’t understand what you mean by squaring the carburetor you should demonstrate the processes and that would be very helpful to those that really don’t understand but would like to tryout your expertise
He is taking about squaring the exposed portion of the transfer slots. Look up transfer slot on Google for maybe a better idea
I understood him to say squaring the transfer slots to where only a small looking square of the slot is exposed but my question is how do you make that adjustment? And would this be true for a ‘70 Oldsmobile Quadrajet?
@@davidmorris826 square it by turning your idol adjustment screw,yes for your quadrajet question also
@@jodypierson3137 I suspect the carb needs pulled to do this? Would adjusting until you just get a bit of vacuum on the port vacuum work?
@@raymondblair3606 you want no vacuum at idle. You need to pull the carb to square the ports. It's the only way to make for sure
I just set up my 750 Holley just like you described. What a difference. I used to get a lean misfire pop though the carb when hot and other driveability issues. So smooth now off idle. Idle is smoother. I thought it was the accelerator pump setting. Glad I watched this. Thank you
Hey brother, I appreciate all your videos. I've been a fan for years and you've taught me personally so much over time. God Bless You and Glad Bless America and God Bless My Fords.
Thanks so much man, I really appreciate it, and I’m glad they have been useful!
Right back at you my friend, God bless indeed!
Most people don't really know the difference between ported and non-ported vacuum. I have run carbs and EFI and tuned them both. For those who do not know there is a special vacuum port on your carburetor that you would typically hook your vacuum line to from your vacuum advance distributor, and that is the ported vacuum. The ported vacuum port has zero vacuum at idle aka no vacuum advance at idle. Now if your hook your vacuum advance distributor up to any other vacuum port on your manifold or carb it will have vacuum at idle and you will get 10-15 degrees of advance on top of what you set your initial advance too with your timing light. So 10 degrees with your timing light plus 10 degrees from the vacuum advance will give you 20 degrees of advance at idle. Now why would you want so much timing at idle? Leaner air fuel mixtures at part throttle down the highway and at idle like more timing. There is less fuel in the cylinder and takes longer for the fuel to burn which is why more advance is beneficial at idle and cruise. It will help to lower your exhaust temps, engine temps, ect at idle by using manifold vacuum on your distributor. Most people also think that high idle advance is only for radical cams which is not true. I have run 20-25 degrees of idle advance on carbs/efi with no issues on stock 70s era engines. 200HP boat anchors in other words. As time goes on there is less and less knowledgeable people about how this old stuff works. Keep the videos coming thunderhead289 otherwise working on older vehicles will become a lost art.
i use manifold vacuum if the engine needs over 12* of timing to idel. most 1970s stuff needs 16-25* of timing so manifold vacuum is the way to go. i have seen how a 70 engin with 12* wold get vary hot switch to manifold it dropped the water temp 20 degrees. used less gas to. i like a fast timing curve all in at 3500 rmp 20 centrifical with a base timing of 2-5* for a totel of 22-25* so 87 gas can be used. this gives a total timing at cruse of around 40*.
If only you made making carbs great again in a hat or even a shirt, I'd definitely order a couple.
To the Man of the 2020 World!!!! Free advice over internet, We all owe you big time my freind, Props n Respect
IMPRESSED WHERE DID U LEARN SO MUCH AND A NATURAL AT THAT
By simply reading and trying things and using wideband o2s and vacuum gauges to monitor everything.
Honestly I’m just an average dude who just has an eye for detail
This channel needs so much more traffic! Your amazing
Thanks great info, I appreciate all your videos. I am almost done rebuilding my 65 289. You have helped me degree cam ,set up Valve train now soon carb setup, much appreciated!
thunderhead video before work? Hell yes!
I saw a video where the transfer slot "square" was set without removing the carb by putting a vacuum gauge to ported vacuum and turning throttle screw out ( closing the throttle plates ) until the reading on the gauge went to zero. It was made by Junkyard Digs, very interesting explanation. I'm going to remove my carb, set the square by sight ( keeping track of the # of turns from closed to get there) then compare it to the gauge method. Thanks for the video.
This is an older video of mine - I taught him the ported vacuum thing that works 85 percent of the time depending on the carb manufacturing. If you have vacuum on the ported port though - it is in fact too much curb idle. You need to advance initial timing and reduce curb idle screw in that case.
@@ThunderHead289 You are absolutely correct on that. Keep up the great videos.
I sure wish someone would undertake the task to quantitatively tune one engine( stock V8 with mild or stock cam say) with Ported vacuum and then tune same engine with manifold vacuum and and at the same time use and describe the adjustable vacuum advance. There is very little on the effects of and tuning the vacuum advance can. It's a tall order but I've not seen that on TH-cam.
Luke, you are awesome. My 78 chevy has been a fun project. After dropping in this sb i just finished rebuilding, the final tuning was at a halt until this video. Thanks man. Hope that good ol ford stays that way for you.
I called Holley and found out that idle air adjust was on the SECONDARIES! After setting the square on the primary transfer slots, it would not idle. There is a hidden secondary throttle plate adjustment that allows additional air for idle. Works great, NO hesitation coming off idle. (1973 Dodge 360 Holley 4160 carb)
Great video. When I bought my truck I adjusted a few obviously wrong things and each one made things worse due to a series of rigs and bandaids that were working in perfect harmony. I ended up saying screw it and redoing the whole top end. It took a lot of work and time but I learned a ton about tuning. I can't say for sure because I changed so much at once but I have a feeling getting the transfer slots right was one of the biggest improvements.
I love these tuning videos. They have helped me so much getting the Webber on my Mazda b2200 running decent. Just took a long cruise to Oklahoma and back to Nebraska last weekend spinning almost 4K the whole way I got constant mid to upper 20s mpg the whole trip
Love the info and love how you run the FB page. It’s really nice when influencers will go out of their way to help.
“Influencer” is way too powerful of a word - I’m just a messenger!
ThunderHead289 Almost forgot to say humble. Thanks for that reminder! Lol
Have a holley coming in the mail soon will been setting it up like this 👍
Ported vacuum advance came in as a smog device. It makes your engine run hotter at idle. Lean mixtures need more lead to burn completely.
And this has been explained so many times that it's just useless to try.
Yes but long duration cams with valve overlap (increasingly used on the street) benefit from a rich idle mixture and high throttle setting, which has given the use a ported advance relevance beyond the emissions debate@@mrblanche
All your videos are awesome; never too old to learn some new info; thanks !!!!!
If you hook your vacuum advance to the manifold the engine will idle faster than it will on ported vacuum. To correct this, people close the throttle and this put the transfer slot into a no-flow dead zone and creates a bog off the bottom. That is why some cars run better on ported vacuum. (ANd yes this was used before emission control but it was then abused during admission control years and hence the bad reputation.)
Awesome video Luke, look forward to seeing the Galaxy ripping hard
Dude me too! Need to finish my temporary hood so it can sit outside!
Love your videos and old rides Luke. Great tips
Luke, appreciate the clarity of your presentation. At 6:17 in the video you mention that when you set your throttle to show the "square" of the transfer slot you
get a "little vacuum signal at idle." Can you tell me if the vacuum signal is measureable on a vacuum gauge. Currently I am getting about 4HG mercury in gear
at 550 RPM. I have timing set at 14 Degrees (I have a comp cam 268 and the car has only 8.5 compression, and yes I know I have too much cam for the compression). The car runs great at full throttle and cruise, but does not get very good gas mileage. Not using a can, and plan to do so after resetting timing curve.
Great video Luke concise and to the point, easy to follow for all levels
Great explanation of the transfer slots! Thank you!
Very information dense. Love it. I now know how much I need to know. Off to do more fun research before touching the carb on my only ride. Thanks a lot!
Luke, I have a question.... I understand about adjusting the throttle primary throttle plates to reveal the "square" of the transfer slots. My question is after the Holley is bolted on the manifold and is ready for idle circuit tuning chain of events so to speak.
1. Turn idle mixture needle screws clockwise until the just bottom out. Then counter clockwise 1.5 turns for each screw.
2. Cap the ported vacuum port for the distributor canister., Connect timing light
3. Start the engine and keep the engine running by opening the throttle by hand to warm up the engine.
4. To set desired idle speed of 750 RPM, rotate the distributor until tach reads 750 RPM.
5. This is where I need help...Using a vacuum gauge connected to full manifold vacuum, adjust idle mixture screws 1/4 turn each until peak manifold vacuum is achieved. NOW... the idle RPM has increased when peak manifold vacuum is achieved. Do I rotate the distributor again to decrease the RPM's back to 750 RPM's or... do I adjust the throttle position screw??? I would think the distributor should be adjusted again to 750 RPM. But I'm not sure
BTW this is a 4165 Holley Spreadbore List 6211-1 800CFM on a 427 Chevy
Michael....that is my exact question too. Luke is advocating that he wants to keep the transfer slot square for a range of good reasons, which is about 20 thou ...a square shape, and he is using rotation of the distributor to set rpm so he can maintain that square shape on transfer slot.....so I think to maintain that square shape after adjusting the idle mixture screws for max vacuum, it seems to make sense to me to rotate the distributor once again to adjust rpm back to desired level......but this is never mentioned by Luke. I think your logic is right Michael, otherwise the transfer slot shape at idle would get screwed up by adjusting the idle speed screw to reset the rpms after adjusting idle mixture screws.
One other thing. The advantage of rotating the distributor vs moving the idle speed screw is that you don’t need to readjust the accelerator pump lever arm from your initial setting. Most people forget that if you move the idle speed screw you must readjust the accelerator pump lever arm to get its gap to 15 thou.
Ooh I just thought of another thing. If you advance the base timing too much at idle (by playing with the rotation of the distributor to get desired rpms), will that result in pinging at higher revs caused from total timing (base plus mechanical and vacuum advance) being too much when the engine revs at an “all-in max timing” which may happen around 3000 rpm? I guess some experimentation is required. I just hate pinging because I want to protect the engine from any potential damage
Holy shit, can't believe a couple of these commenters. Can't win 'em all I guess. Appreciate your insights here. Always planned on going FI because gadgets, but the more I dig into your series it makes me reconsider.
You should see some of the ignorance that I decided to remove.
Followed by the “well on such and such channel, they said this” - I don’t like to make war between channels, but the bad tech presented by large channels out there is appalling
@@ThunderHead289 I believe it. In any case I really enjoy your content. Don't let the bastards get you down!
All of this is fantastic info (except for the misinformation about ported vacuum advance). THx for sharing
Folks who say ported is designed for emissions are just wrong. So some engineer (unverified) made a claim about it that everyone has run with for years. I'm also an engineer, I also work with engineers - not all engineers are smart nor do they know what they are talking about.
@@ThunderHead289 I would say David Vizard knows what he’s talking about. That’s exactly what he says. I’ve argued with many on the subject, thought long and hard about it, and nobody has convinced me otherwise.
@@ThunderHead289 Ported vacuum is to keep NOx emissions under control at idle. That's it. It is more desirable to run manifold vacuum advance. One big advantage is your engine will run cooler at idle. If you have issues with idle speed and full manifold vacuum advance, you may need to find a mechanism to limit the total amount of vacuum advance.
Hello Luke, I’m a big fan of your tech tips, - your way of explaining things suits my learning curve perfectly. I’m not sure if you take requests, but if you’re looking for ideas - may I suggest a run through of steering box adjustment. I’ve just stumbled through this myself, and there’s not a lot out there that I could find anyway.
As always I love all the info you and JYD have on your sites. Couple of comments. 1. since you daily this truck with a late model 302 and the O/D trans. with the factory 3.70 gears what kind of performance do you get. MPG, driveability, etc. 2. You guys need to get some of your stuff on Mr. Regulars site. Maybe get him to bring the Falcon out here to Iowa or he and the Fuel Injection sucks guys can bring the LS Winnebago home to Forrest City, and then he can review this truck. LOL!
Please help Junkyard Digs with his Galaxie. It's too sweet a ride to just get rid of when he has friends like you who can fix almost anything.
Another excellent video. Thanks for sharing your knowledge with the rest of us.
Thanks so much for the positive feedback
Check this out , I have flipped over a 750 holley and a demon to check were the transfer slot. Comes into perfect square is right around 1 full turn from just making contact with the throttle lever , so if your not taking carb off that's a very good starting point
THANK YOU!
Nee subscriber here. Working on a "70 F-250 with a small block 360 and a "67 Ford Ranchero.
"MAKING CARBS GREAT AGAIN!" 👍
thanks for the video... always interested in the Galaxie progress.
Luke....love your videos and have learned an enormous amount. Thank you so much. With respect to transfer slots, I need to unbolt my Holley 4160 and flip it over to inspect the size of the transfer slot. Is there anything I need to be careful of when I do that....obviously spilling fuel....but can I damage anything by flipping it over? I am going to check my slots because I appear to be showing 3 inches of vacuum from the Ported slot, and you said in another video, that might be due to the transfer slots not being set properly....as the ported vacuum reading should be zero at idle. Many thanks
Im illiterate on the subject of carbs as a lot of folks are, could you do a vid showing where / what everything runs to when talking about time, vacuum fuel etc. thanks
Hunter Jackson I completely plan to, I just need to find the time to do so!
You may want to check out Uncle Tony’s garage... he did a video on the basics of how carburetors work
Thanks bud I’ve been chasing a carb issue on my Toyota runs good till you give it the gas pedal then she chokes
Thanks for all the helpful tips you've lent to all of us over the years. All of your advice has always been helpful.Question....Would your O2 gauge set up work with an older and richer running flat tappet motor?
It will definitely work!
If you thumb through my “recent uploads” playlist, I actually have all the links in the wideband o2 video!
first of all, thanks for your continued efforts on these videos and sharing your experience and knowledge with us out here. i know you have a video or two discussing the differences between running manifold vs. ported vacuum from a debated perspective....but is there any hope for an actual "how-to" with actual footage of each step to include adjusting the canister, etc? i.e. if you choose to run ported vacuum or manifold, set you initial timing like this: (insert video link here) but here are the specific differences, and i'll walk you thru why they are so important. Just a thought. in any case...thanks again, and looking forward to more content! Cheers!
Blake, you know what - maybe I will shot a little intro video to a series like that. Iv been meaning to for a long time - tomorrow might as well be the day
@@ThunderHead289 i think there are plenty of folks that want to at least try to run manifold vacuum, but hesitate cause they dont want to screw up their rides....myself included. Your videos are always very clear and comprehensive. Thanks for responding so quickly! If you ever make it out to western Montana, the beer is on me. Cheers!
Thanks a ton Blake 👌
Old post but new comment. How do you adjust the primaries properly? Choke open or closed? Could you make a video on that with curb idle speed screw?
Since 1970 , ive used the two man ,power braking method to set my carbs --- and my timing ! You can also put the bumper against the tree , but its not safe at my age ,plus you dont have the vacuum draw on the brakes .😂🤣 Great to see old skool young guys teaching others the lost ways . Plus im a big fan of eec ignition ,points are pointless imo . Many are lost as far as grommet color coding for brain boxes and distributer plugs 😵 but that's a whole nother vidja . Thanks buddy love your content as always keep scrapping the motorcraft toilet bowls. 😨😂
Your bumper against a tree reminds me of my college roommate in South Dakota. We lived in a small house with an inclined driveway. In the thick of winter he enters the house and asks if I would help him get his car up the driveway. We walk out and find his 73 Vega, tires spinning in the snow, trying to inch its way toward the house. I think this may have been a very early version of an autonomous vehicle.
What does setting idle to square mean
Adjust the butterfly so their is only a "square" section of the transition slots exposed .
Next ! Initial & advanced timing video ?
I can, I have a very simple concept there also - really this stuff isn’t as hard as everyone makes it out to be. All the bad info and misinformation out there has made it seem difficult.
www.hotrod.com/articles/ignition-timing-free-hp-heres-get/
In your opinion, is a 600CFM carb a good fit for a 390FE? The motor is old, but still runs good providing about 17 to 18 inches vacuum at idle and is pretty much stock and had the intake changed to a Ford Police Interceptor aluminum unit way before I got the car. Its been having some issues lately with the Edelbrock Performer 750CFM it has. A friend of mine gave me a Holley 4180 600CFM to rebuild and try out. This carb is a factory Ford original unit from a mid-eighties F250 (Mustang 5.0 liter in the mid-eighties used the same) and has huge primaries, vacuum secondaries, electric choke and is an emissions carb having extra vent tubes coming from the float bowls. I was going to rebuild it and give it a shot, just want to get your take on it. Thanks for the vids.
390 Cougars came with 600 Holleys.
I like your videos, I got an old Q-jet I bought and got the overhaul kit. Now it works really good, and I didn't have to do much tweaking either. But I will get the wideband lambda to check how well I did and do fine-tuning. And I like that song at the end of your video, what's it called?
Q-jets always run good on near stock engines.I doubt that buying a wideband in your case would be money well spent. They use metering rods which to me are more mysterious than simple jets. One issue they do have which will greatly affect driveability is wear between the throttle shafts and the main body of the carb. If you try to wiggle the shaft up and down you should not feel any play. If you do they are worn and prone to air leakage.
Would you mind doing some motorcraft tuning videos? Mainly the 2150? Only reason I ask is because thats what I have a normally on smaller engines (V6) still have the old 2100 or 2150 carb.
Ive learned a lot on my own but you are WAY MORE knowledgeable about carbs than me. Plus, inform people who dont know as much.
put a bronco 302 in my foxbody mustang, didnt know the major differences until i drove it x.x
What are they?
To bad you don't live in Longview tx. I need the carb and timing set correctly on my 63 Ford Falcon.
What do you do when you square off the idle slot and it idles low or not idle at all?
Have a problem where we have a brand new edelbrock carb on a 390 fe and we made sure with the motor at TDC ( compression stroke of course) it was right inline with #1 plug.
Go to fire it and she won't idle at all, tried advance it as far as it go then it will kinda idle but at like 550rpm and the timing light shows about 49 degrees advance ( vacuum advance unhook).
So not sure what's going on.
Also I did notice if I put the timing back where it was ( roughly 14 degrees ) and made sure to back off the idle screw to where it was ( turned it up to get it to idle ) I could hold the secondary open a little and she would idle low but would idle without messing with timing.
Any ideas?
I've got a 1967 Ford Econoline van. It's got a straight six 240 CID with a 1 barrel carburetor. Do you have any advice on whether I should still use the original oil bath air cleaner or change over to some kind of aftermarket air cleaner?
Thanks a lot, Tom
My 67 Bronco, with the original 289, used to vapor lock all the time. I added the wood style spacer still did it. Added a fuel cooler.
What the heck is a fuel cooler you may ask... Its an old power steering cooler from a Ford explorer. Yep... See... My fuel was hot coming out of the fuel pump. My fuel pump is heating the fuel up. Sounds nuts I know, but it was.
Ill upgrade to electric when I go EFI later.
great video,s!! how does one adjust throttle plates in the idle circuit?? thank you, PJP
I have a edlebrock 1406 on my 302 with a small .456 lift cam. I jetted it to .100 primary jets and
.98 secondary jets. My fuel is pretty close. I am using a wide wideband gauge. The issue im having is fuel leaking out of the bowls. Its hard to start cold or hot. It used to only be hard to start when it was warm.
Verify fuel pressure. Edelbrock likes 5.5 lbs.
I was watching a video from webber carburetors,And I thought that the guy who was explaining how to tune them said it better than anyone else had in all my 55 years! That screw on the side of a carburetor that everyone of us has turned the crap out of when we were rookies! Is not for tuning the carburetor. He said all that should ever be turned would be just enough to keep the throttle plates from connecting with the side of the throttle bore and causing a depression if the throttle was to be let go of and snapped back closed! Absolutely no tuning benefits beyond that! Once I heard it explained like that I wondered why in the hell didn't someone tell me that years ago?1🤔
Hey just out of curiosity. I have a dumb question. I've been playing around with the timing on my chevy 350 in my 82 k10. Its bored .60, has headers, mild cam (comp 280H), not a ton of lift or duration, it just idles sorta lumpy. Double hump heads with 1.92 intake valves. I've had my timing set at 8 btdc, I'm trying 12 now. Do you think ita needs more? People have told me 8 is plenty, which I highly doubt. Some people have told me 20, which seems like too much. I'm not interested in the "all in" timing right now because it's a slow 4x4. I'll mess with that later. Just wanted to pick your brain. Thank you in advance.
Where in Iowa?
I switch out the ignition module in the distributor of my 350 5.7 i got spark but it would start it back fired. Also no matter how many times i turn the needle and seat i cannot get fuel into the front sight bowl
Wow I didn't expect to see so much salt in the comment section 😅🇺🇸 I'm in the middle of your process. My carb is adjusted correctly and I'm putting in timing to the engine. I'm at 18 degrees initial now and I need another 200 rpm to make the idle smoother/better vacuum signal. How do you know if you've added enough initial timing and if you need to start modding the carb (air bleeds/holes in butterflies)? I have a large cam with loads of overlap. Carb is crispy otherwise. Thanks for the vidoes 🤙
TheSaxon25 this is where it can get tricky to tune via messages because I don’t know the build or your dynamic compression scenario - a lot of times guys overcam a bit and have low cylinder pressure at idle dictating the need for more timing.
The one thing I can say is that everything is a balance, and you may be able to get more vacuum/higher idle based on how rich your mix screws are set - I’d look here next, and allow yourself a 1/2 more turn from the squared off position with a big cam.
Generally the square is for 800 or less - as idle rpm increases, this needs to be opened up a bit to compensate. But if you can help it, minimize your throttle opening input 👍
@@ThunderHead289 thanks for the reply! We built the engine around the cam and heads so I know the parts are congruent or at least theoretically should be okay together. Part of the reason I am hesitant to raise the timing is because the MSD pro billet distributor I have doesn't allow for an advance stop bushing at 36° if I go over the 18° initial. 😅😅 I just ordered a wideband. I think that will let me cheat enough to figure it out 🍻🍻🍻🍻
@@TheSaxon25 How much vacuum do you have at idle? If your idle is not super choppy due to cam overlap you can use direct manifold vacuum advance which may get you the 200 rpm you need.
@@65sohc hey dude. I have 6-7". The car has a lot of chop. Isky z-35 cam. Steady fuel pressure, floats are perfect, transfer slot is slightly over square, no vacuum leaks, four corner idle set at 2.5 turns out, speed demon 750 VS (gen1), probillet msd distributor (no vacuum advance), 6al msd box. I'll find a fix that doesn't involve switching to fuel injection 😂😂😥🍻
@@TheSaxon25 Yeh. That's sounds like a pretty healthy cam with too little vacuum to run straight manifold vacuum advance even if your distributor had it. Even though you're at 18 degrees initial you can still try creeping it higher. The only limiting factor is if it becomes hard for the starter to crank the engine over.
Would this work on a quadrajet?
You said your initial timing is 14°. Did you have to adjust the distributor weights so the timing isn’t too far advanced? What is your total timing?
Any way to popstion primaru transfer slot correctly wirh out removing the carb. "Vacuum at idle"' does this imply that the ported vacuum connection will show some vacuum? Could one use the the vacuum signal at the ported vacuum connection to set the amount of transfer slot exposure? Say, adjust idle screw untill vacuum apwears at Ported connection then back it off until it just dissapears?
I need to get a wideband o2 guage.
I just had my mechanic install a brand new stock 2150 carb on my 77 Ford with a 400. It seemed to run pretty good until it started to vapour lock So I did the old heat shield around the fuel line and clothesline pins method. It hasn’t vapour locked yet but I haven’t really been driving it much either but now it seems to be blowing Black smoke??? I’ve been running shell V power in it and can’t understand why it’s blowing black? I don’t know if it’s a blown power valve or if it’s trying to vapour lock?
Hello Thunderhead 289,
I just purchased a 62 Chevy C-10 it has a 327 motor bored out to a 355 with a Edlebrock Carburetor. It was running a little ruff at the idle when I test drove it and thought this guy just doesn’t know how to time the truck so I bought it. I noticed the vacuum advanced hose wasn’t hooked up and thought that was weird. I set the timing on the brand New Carb and thought I was good. When I drive it the idle jumps after I set it. It does t want to stay idled at stop lights and I have to keep it going giving it gas. I set the timing and went to 6, 8 everything and the idle still jumps. Any ideas?
Ray
I could use your help identifying a particular engine in a 66 Thunderbird. I have lots of reason to believe it is not the standard motor. I'm more of a Chevy guy so any help would be appreciated.
I'm not understanding transfer slot to square. Can you zoom in on it. Is it the little spot by the plate?
Hello Thunderhead, My name is Mat or modiemat1978. I picked up an old 1980 Chevy Camper Special about a year and a half ago and have been chipping away at it. When the budget allows. I am having trouble getting it to run smooth consistently. Three times the it seems like my float adjustment has moved all by itself. I have watched all your videos and I think I have the order of operation for initial carb set up. But, I have some specific questions and info for you to ponder. If possible can you help me? Sorry its so late I live in on the west coast.
Where is the ported fitting hookup on the Summit carb?
I'm a Ford guy, like you, but this is about the Summit carb in particular. Have you had issues with the threads being too loose with the idle mixture screws? On my 600 cfm vacuum sec. the slop is so bad that it creates a vacuum leak, the screws are extremely loose. Have you run across this issue? Do you have a fix? I've thought of a couple, but I'd like your opinion.
Good luck on "ol'man 65" It reminds me of the 69 Ford Custom 2dr post that I had years ago. It came with a 429 from the factory; it was a special order police package car from a small coastal town in Georgia. It ran and handled really great; unfortunately body rust was its nemesis. Thanks for sharing your knowledge and videos.
I've got a Summit on my 66 Mustang 302 and haven't had that sort of problem. Maybe some teflon tape on the mixture screws?
@@65sohc That was a good idea that I actually tried; I appreciate your input. It works, but I'm looking to make a better fix and was wondering if anyone else had this problem.
I'm considering the possibility of installing heli-coils if I can find the right thread size. I know that these particular mixture screws have a different thread size than the Holley 4150/4160. They're bigger in diameter, but they share the same size as the Holley 4010. They aren't available separately either so if you mess one up in the process, you're on your own. Maybe I can achieve a fix by using one or the other, I'll have to see.
I think that the problem was because this particular carb was one of the early castings and as luck would have it, I was awarded the challenge of fixing a defective piece. I really should have returned the damned thing.
The real reason that I bought it was because it was an updated version of the Holley 4010, which I liked the design, especially for the annular boosters.
@@williamcharles9480 Good luck finding a heli-coil that small.
@@65sohc That's what I was thinking, too. I have seen some pretty small sizes, but I haven't researched that particular thread size yet. Another option is good old JB weld. The original formula is pretty tough and chemical resistant. It should be able to hold a thread. We shall see.
@@williamcharles9480 I hadn't thought about that. Project Farm has some great videos comparing the various formulations of JB Weld to similar products and it is always near the top.
Does setting the idle circuit apply for 2 barrel holey carbs as well?
Set to a square? What’s that measurement based on?
What does squared off mean?
From the underside of the carb, with the throttle closed, only a square of the transfer slot is showing. From this point, you have about a half turn of the curb idle screw before it starts causing issues and drawing too much from other circuits.
If you need more throttle, try advancing the initial timing instead
Hey Luke. Always enjoy your videos. Very informative. Just one question though. If I make my transfer slots square my engine does idle too low as you mentioned. However I don’t have the luxury of being able to adjust my timing to be able to bring the rpm up. If I set my initial timing any higher than 8 degrees I get pinging under load. Any other suggestions how I can get around this issue?
I have a demon 625 and if I make the transfer slots that size it opens the two barrels more. Is it possible that the two metal flaps, I don’t know the name were installed backwards? Any help is greatly appreciated.
mine keeps idiling rough whats the base line for Idle screw. i know the fuel mixture for holleys 1.5 turns but not sure about idle and car some times runs on after shut off.
What does Squareing the carburetor mean?
I consider myself highly proficient in tuning carbs...just not particularly successful. Any advice?
As soon as you install a wideband o2 gauge, everything becomes very clear as far as what needs to be done
What do you mean set the port to a square?
To where on the underside of the carb, the transfer slot exposure is at a square vs more exposure would be a rectangular shape as you expose more and more of the slot
Great job Luke that explains a lot of things I didn't know. Thanks
Hey, I have an engine Chevy 350-365 HP, What size Holly do suggest, I like the Holly, Thanks
My truck has no power steering or brakes it drives horrible lol I guess what I am asking is do you have any ideas how to improve the steering and breaking on a none power steering or brake 1971 f100?
What about centrifugal advance? Doesn’t that advance timing with more rpm?
Will this method be about the same for a Rochester 2 barrel?
good vid.
I just bought a edelbrock 2x4 intake and carburetors. I have a 57 chevy 283 small block. In 55 56 and 57 they run two carter afb carburetors. How do I tune thus set up to make it work on my car?
th-cam.com/video/OYylACoMd4M/w-d-xo.html
I hope you see this thunderhead. I was wondering what I could do to make my none power steering or brakes f100 drive better? Do you have any tips?
What do you mean?
That’s how my truck is set up - what are your concerns?
Off the subject but being from Iowa do you ever listen to William Elliot Whitmore?
I’m digging my grave oh lord I’m digging my grave!
I feel like that’s my life’s song
ThunderHead289 lol you and me both my friend!!
I don't. Just never liked his stuff. Personal preference, he has some fans.
I don’t understand the phrase “set it to a square”. What does the square mean? Thanks!
Hi bro got a ? I have a sbc with a 292 cam dart pro 1 iron heads I got time set on 12° and 750 summit carburetor . It starts and ideals good but will not take gas and backfire through the carb when I try to Rev it up in park .put in gear and try and get it up on the stall (3500) it black smoke like it's flooding and pops and cracks will not evon turn the tire over. I have watch your carb videos and vacuum
advance video im running out of ideals. He dis with vacuum advance
so set transfer slot to a square and dont touch it unless i want to idle at 700rpm or more. In that case open up the slot a half turn. ???