Mr. Powell, I truly believe what you are supplying to the UA-cam community is just invaluable to so many people, this 66 year old gear head can attest.☺️Like yourself, I came up through the school of “tweak it until you get it”. As a dyed in the wool Mopar fanatic, I can say wholeheartedly that what you are teaching the masses is the rules of universal law that are applicable to all. I campaigned the “Sixpack” cars for years and I learned a lot through trial and error…And a vacuum gauge! I can tune the dog squash out of those 2300’s any more and I even supported the hobby, albeit briefly, with my own design of outboard carb idle screws and a close-quarters adjusting tool that many have used in the past years successfully. Sorry, I digress. One thing I am glad you mentioned is the boosters. Those things, the fuel will creep out of to compensate for poor idle with low engine vacuum as well, which is what I would experience, especially with the big cams that I do. Here again, you touched on it by drilling the butterflies and changing to a lower numerical PV. I also tune this area with idle bleeds as well. Holley carbs are so much more forgiving as there are several different areas that work in conjunction which help the neighboring fuel transitional period with their superior design. Thank you so much for this insightful series. 🫡🫡
A 1980 tuneup was on a 1966-1977, so factory stuff was dust out, on a “Sun” machine, repair pivots, replace vacuum advance if needed, points filed for good ground. Condenser are used to allow current a place to go after points opened. Unplug vacuum from intake signal at carb, set to 10 degrees, pull out dial advance timing light, watch springs open, vacuum advance add (Note: 2:1 ratio, so 8 degrees at distributor is 16 at crank), total 34-36 degrees at 2,500 RPM, 4-gas in tail pipe, +/- 1ppm HC, 0.5 +/- CO, 19% O2, in-clamp air pump, check HC warm at idle with propane enrichment tool-canister-flow valve, PVC, fluids, tire pressure + spare. Test drive. Tune done w/new plugs, air filter if needed, trans/diff fluids and park it. Pays 1.5 hrs. 1980 tech flat rate @ dealer-$6.90. Aftermarket shop $11.00 Great info on Holley carbs. Now, 2024 the Holley group owns 70+ companies! Google it.
My gauge went super rich just as you described. I went 28s front and rears and the results in my instance was night and day. Had 31s front n rears previously.
A couple of comments, Holley makes anti-pullover discharge nozzles that can fix the issue you described. Regarding drilling the front butterflies, sometimes you can adjust the secondary throttle shaft stop screw 1/8 to 1/4 turn open, and crack those butterflies open a little more and achieve the same fix, allowing the primary butterflies to close and keep them below the transfer slot, but you can't go too far on the secondary stop screw and get out of their idle circuit. It's worth a try before drilling holes in the primaries. Good videos, hope they help folks!
@@powellmachineinc , interesting. Sounds like a vibration/frequency issue. We use 2.3 Fords in a marine application. At wot, 5600 rpm the engines would develop a surge. Kept thinking it was fuel related and couldn't find anything wrong. Finally put a timing light on the engine and saw the timing would retard 15 degrees then jump back up to 32 degrees once the rpms dropped. As soon as it got back to 5600, the timing would retard again, kept happening over and over. Turns out the fly weights in the Mallory distributor were bouncing off of the stops due to the engine's frequency/vibrations at 5600. Distributor checked fine spinning it in a Sun machine. Had to change weights, springs and the stop location to get the advance mechanism in another frequency range. Live and learn, never give up.
An anti pullover squirter won't fix the problem on a 4 cylinder ford engine, been there, done that and got the t-shirt! I think the little umbrella check that let's fuel into the pump from the bowl is vibrating and becomes a pump. I had this same situation and fixed it with an old fuel bowl with a captured ball check in it.
I helped a friend this past week sort out his Holley 850 on a stroker small block Mopar. It had an off idle bog. It never coughed back through the carb when bogging. He tried a lot of different things only to find out that the metering block wasn't drilled properly for the idle transfer slot. It took three of us and about 20 hours to determine what the problem was. He's 4 states away and he was able to enlist his local race engine builder's help. Talk about a challenge to find.
@@powellmachineinc I have one where you can't get the transfer slot to show up under the plates unless you really open the blades. They just aren't long enough--850 mechanical QF
Thank you so much. I certainly hope people will listen to what you're saying because it's extremely clear and that you know what you're doing. I've been tinkering with this stuff since the late '80s and it took me a long time to find out a lot of this information. Still learning things I did not realize the float level had that kind of impact. The manifold vacuum and vacuum advance for anything you drive on the street is absolutely critical. Most GM distributors pre-pollution control ran 12 to 16° additional vacuum advance at the crank and I have found that to be right for most applications.
Call me hardheaded, but I do like figuring these things out as best I can, noting that a metering block is an interface module: one side brings fuel, the other air - and the air helps manage the fuel. One of the odd things about emulsions is that [to a point] sizing them up can deliver more fuel to the boosters because there is less mass to lift [being aerated] - volume delivered can accelerate for the same signal. Air bleeds primarily dictate how much signal is needed for mains [booster] to come on. Regarding emulsions, the lower they are, the more signal at the booster is needed to start air introduction/lift fuel. Some of the craziness of the past two decades began with some magazine inspired articles about resizing air bleeds... which is probably the dead last thing to tweak in most cases, but it can happen. Holley got most their stuff right, and modern improvements are mainly float bowl design, needle & seat, and booster design/location. It does appear that boosters being just a bit lower in the venturi bore is a general improvement regarding fuel shear and signal response vs older designs - base of the booster being roughly midpoint. I'm not at all going to claim guru status... but just maybe read a little too much, alongside making classic mistakes years ago such as trying to tune my way out of needing a valve job. That, um, did not work by the way - valve runout was a disgustingly large number: maybe 0.006" or worse on five valves between both heads.
I didn’t know everything you shared with us but I completely understood what you said. Knowing what’s in a carb does not mean you understand how all the parts relate. Absolutely the best overall explanation I have personally ever heard. I especially appreciate the explanation of the relationships between air bleeds emulsion tubes and float level. Thank you!
Another excellent video of speaking hands on knowledge. I appreciate what you guys are doing here and the real life content you’re putting out. Keyboard warriors are just that. Those who can’t or haven’t and will not,are those who attempt to tell others where they’re going wrong. Excellent job with keeping your cool,you’re a better man than me for that. Appreciate you guys and and all you do.
Thank you Daniel for the blast of carb info. I am going to replay this vid so I can catch all of what you are pitching. I do carb rebuilds but I have to admit I do a" little alcohol".
Great info. Thank you. I now have a much better understanding of the emulsion circuit. I just purchased 2 used holley 750 hps to put on my tunnel ram on my boat. Engine is oval port solid roller 427. Both were out to lunch so looked up the factory calibration and i am starting with that.
Respectfully of course, and I will gladly stand corrected if shown to be in error, but as an auto service student in the early 80's, I believe we were taught that ported vacuum was used beginning with the early efforts to clean up emissions at idle by leaving the timing un-advanced. One other thought was that mashing the throttle from idle meant vacuum advance was lost which in some cases produced a stumble. Please keep in mind that I am referring to stock engines, not modified stuff. Thank you for your excellent vids and info!!
Correct. Ported vacuum was used to make the engine rot hot as shit at idle to lower emissions by keeping the exhaust much hotter than normal. (basically overly retarded ignition so there were raw flames in the manifolds). On engines with parasitic air pumps, the extra fresh air could continue the burning process in the exhaust pipe because there's plenty of unburnt air and fuel in there due to the retarded tune (and lowering your gas mileage doing it). If you get an OLD paper repair manual you can look at the vacuum MESS of lines going to the carb, manifold and distributor. They'd have a thermal switch usually on the thermostat housing. That switch would see the car running hot in still traffic and switch the distributor over to manifold vacuum to avoid a meltdown. When that happens, the car would rev up causing the fan to spin faster and make the timing closer to where it should be all the time. By not running retarded as hell, the engine could cool off because it wouldn't intentionally be boiling the coolant around the exhaust ports anymore.
Nicely done, learned tons. If you had a Patreon account, I would be inclined to send a couple of dollars a month. UA-cam you only get half I believe, but I don't see the THANKS button to give here either. You should get paid for your work
It's about to get real interesting for me. Out side of what you have covered so far. I just don't have any knowledge of, but am very interested in. Thanks for the refresher. I haven't thought about this stuff for quite some time. You've got my head in gear. Ha!
Very good information with this video. You have obviously had many experiences with Holly carburetors. I personally was never a big fan of Holly carburetors but I think it was due to people buying a Holly that was way to big for their stock engine and then bring it to me wondering why they have lost power and using more fuel 😂😂
nice show mate very informative and thanks for sharing your skills and knowledge keep the good work up perfect tutoring skills executed perfectly you would make a brilliant automotive education teacher when you get to old for picking up heavy engines and cyl heads, here in australia we call them tafe teacher (technical and further education)
great video thanks for sharing i also always run vacuum advance how much advance depends on so many things just have to in my opinion go up and down until engine is happy. we call the boosters drop boosters in southeast Alabama. i have a pile of 50cc pumps i have pulled off and at one time thought everyone needed one until i learned better.
Analyzing someones so called carb issue is like taking the bull by the horns. What people need to realize is so many things affect carb adjustments, etc. Tall gears, heavy vehicles, cast iron manifolds, too much cam. The list goes on. I always recommend an O2 censor and especially a vacuum gauge. Especially the latter for carbs with a power valve. Great video!
got a neighbor with a semi built street motor.holly double pumper stumbleing when secoundary opens up.suspect timeing and or fuel mix screws.gona put a vacuum gauge to set screws an check timeing.maybe check that rear float adjustment.burning rich.thinking the same way.thanks daniel.most people dont have a clue
i gota tell ya Daniel...u r dead on the money...when u said..u cant beat a GM HEI disturibtor...!..i live'd it first hand..!..the only issue that they had...was over 8000 rpm the kv's would drop off..mallory made a power cell...u just mount it on the firewall & connect it inbetween the brown wire run'n from the distribetor to the coil....and wala...no kv drop over 8000 rpm...!..holy reliable...!..& a dame site cheaper than (@ the time) an accel distributor...&..car ran the same time with either distributor...!..Thanks for the carb serious....!..great idea...!.p.s. of course that was shimed & the lightest springs in the stock HEI...!..no plug foul'n, misfire'n,break'n up...could NOT tell the differance..!..
Nice. Makes sense now. Chrysler/ Dodge run ported vacuum and Chevy runs manifold vacuum. I loved the Mopars and thought ported vacuum made sense. Not anymore! No wonder i always had problems with pinging! I was essentially adding timing under load when i should have been pulling timing out. That's what happens when you try to learn how to modify smog era junk with no experience of what worked before then. All the Chilton books i have or had didn't help nothin'. Now i know i could have dialed in 36 degrees total and let the idle timing land where it is; and if the vacuum advance became a problem just unplug it; yeah, i wish i had a time machine and go back 40 years! Damn!
I've been told a low stall and or heavy vehicle will usually require more squirter and a came adjustment. The more load off idle, the more demand for fuel squirter and cam lift and or duration. Until the signal in the venturi starts pulling fuel and the load demand lessons.
Really good information on the emulsion wells. Can you share more information on the air bleeds? The reason some people use ported vacuum is they have low advance at idle and as the throttle is opened it adds timing and makes the engine feel more responsive. With more initial and less in the curve for the same total manifold is better, just like you explained
Yeah, there's a whole bunch of 'experts' and 'gurus' out there that don't understand how things actually work. But REALLY think they do. Same as blocking off EGR, you have to tune the timing curve to work with your now 'more correct' tune. Ported vacuum was just a government mandated crutch to make an engine run like crap at idle to lower emissions.
The vacuum advance part of the discussion interesting. Between ported and manifold, I didn't think the actual vacuum signal was any different with any specific load when comparing the two. Just not present at idle with ported/timed. Only reason I say that is you mentioned potentially having too much vacuum advance under a load using the timed port. On my Ford big block, I measure like 18 inches at the manifold and same at the timed, just only once the throttle plates open enough. I thought under a load, the signal would drop to the same regardless of which side you have the canister hooked to. I dunno. This carb series is really interesting and I appreciate you taking time to go through it.
That’s exactly right, once the primary throttle blades are cracked open a small amount the ported/timed hole in the base plate is uncovered and subjected to manifold vacuum also, so they would be the same from that point on. At wide open throttle (WOT), the manifold vacuum would fall to basically zero, and so would the ported/timed vacuum. The myth that ported/timed vacuum increases at high rpm and WOT needs to stop. Where is this magical ported vacuum source coming from at WOT?
I have been tuning and rebuilding Holley’s for over 50 years and I get pretty good results. The thing I wish someone would come out with is tuning multiple carbs mainly two carbs on a blown application. I have a 871 blown 406 dart engine. I have been fighting with the carb adjustment for years. I can’t find any instruction on how to tune a blown application with two 4 barrels.
I think ported vacuum (for ignition timing) is mostly an emissions thing that normally need to be accompanied by a functional EGR system to be of any benefit.
The only application for ported vacuum advance is for pollution control in the '70s particularly pre Cadillac converter. It caused the motor to run hot at idle and still be firing charge in the exhaust to emulate a catalytic converter. No engine is ever going to run right like that
PSI - NEEDLE & SEAT REQUIREMENTS? Can you speak on the Minimum & Max pressures required for each size of needle & seats? .097 vs .110 vs .120 vs .130 Each requires something a little different but what is that PSI requirement? Is it listed somewhere? And thanks for putting your knowledge & experience out there for us.
Don’t you think he is in the transition slot area of the fuel curve…Doubt the booster is even active yet especially if straight leg booster. My humble opinion.
Very possible, I bet the booster is flowing, butI do think a IFR change may be the answer after I think about it further, definitely a good suggestion and we will go over that next video
hey MR powell im new to your channel and really like the way you teach about all aspects of whatever your doing thumbs up ||| I got a issue with a small block chevy 355 that for some unknown reason NOTHING has changed or fixed the problem its very strange condition happening when your at cruise speed (2200 --2700 ) engine turns headers red and engine temp rises quickly all indications are a lean condition BUT installed wide band and it shows rich 10.43and plugs show rich have jetted down to .064 ---- 4.5 power valve timing is locked now at 34 deg. tried SEVERAL different things all to no avail IF your up for a challenge please get back to me thanks JEFF
Thanks for your response. The wideband read at 11.22 after the jet change should be Lane at this point, but still showing rich I have been as low as 54s on the front side trying to limit down to no avail so far have tried four different carbs, 5 different ignition systems, change valve adjudgmen imaginable timing locked with vacuum advance, etc. in all positions@@powellmachineinc
Thanks for responding Mr. Powell I hope I’m not sending multiple responses. If possible I could call you and explain what all I have done and what all I have tried and see if you have any suggestions or if you would like to call me I would gladly give you my number. Thanks, Jeff.
Air Bleeds. Could you talk more about them please? What I know of air bleeds in the fuel circuit, is that the make the fuel flow more, richer you could say. Air bleeds make the fuel flow more by lowering the surface tension of the gasoline on the passages in the carburetor. There is another example of this, when hydroelectric dam engineers introduce bleed air into the penstock tubes that feed the turbines. It lowers the surface tension of the water, and more water flows, and the dam generates more electricity. Anyhow, I don't think many people actually know what air bleeds do in a carburetor. Could you please explain how they can be used to tune a Holley? Thanks. ---Doozer
Turning motors is one thing, but, if you can run some EGR... When warm, vac advance initiates EGR and combustion chamber contents are burning with more heat and lower temperature.
Great video. Thank you much. So you were saying annular boosters flow too much fuel? Is that what you think? My 3310 Holley worked pretty good with annular boosters but it did use a lot of fuel. Maybe too much.
It went to 11.22 the carb is a proform 750. 4 corner idle adjustment front mixture screws make very little if any difference transfer slots are pretty much closed setting idle with rear. Have been as low as 58 on jets but still rich. Tried 4 different carbs and 5 different ignition systems it’s driving me nuts lol. Thanks in advance. I’ve tried any and everything trying too correct it idk thanks Jeff
I know I just can’t find it. Ran a internal vacuum leak test and found it had 1 in lb blow by. I’ve tried 4 different carbs etc. nothing has worked. Thanks for your time and help. Jeff. Ps would like to discuss this further with you if you’re interested in helping me try to figure this crazy thing out. ??
Finally got this thing lean drilled holes in base plate. Still not much difference in idle screws on primary went with 64 jets front and rear still runs rich at idle and lean at cruise speed
Cranking compression is 175-180. Rechecked cam centerline is within a half a degree. Still searching finally got it lean at cruise but it’s rich at idle. Trying to find that line
There is a bit of truth to timing messing with your tuning of the carb. You obviously have a good idea of what's doing what. Just like anything else you are modifying it's a whole package not just a Facebook marketplace shopping list. I just saw tkms video on valve springs being a drop in. People will always think they are making a better mousetrap but not optimizing the package to work in your application.
What causes you to be on the main jet at idle? Booster looks like it is "leaking" from mild fuel flow... Runs great, afr is fine... Too much throttle blade angle? It doesn't really seem like it is too much but idk...
I bought a Holley a guy, it came off a 604 late model engine. It’s got adjustable air bleeds, could you go over those? What does what when you change them. It has 2 per barrel. I have seen some carbs with 3 in catalogs? Just curious about those. I’m getting ready to swap a carb on my 95 5.0 and need all the help I can get.
checking on two things. 1. fuel shouldn't be coming out of accelerator noozles except when pump is pushing it out, right? 2. is there a carbs 101 ep#3?
At 31:30, Are you saying that having your distributor vacuum advance connected to a ported/timed vacuum source will ADD additional timing at wide open throttle? Engine vacuum, whether manifold, or ported/timed, will be a zero, (or very close to it), at wide open throttle, right?
Ok just for my own knowledge idle o2 is set by the mixture screws but off idle it can go rich or lean cause the only thing setting the mixture is the idle fuel restrictor. So does a guy lower float level, open main bleed .001 or .002 , change idle restrictor. I would be nice to somehow have a throttle position sensor to see where the throttle is compared to what circuit is actually causing the issue using a wide band. Sorry for long rant
I can tell your no real motor guy because you've got one of those crapy Craftsman screwdrivers. Nobody uses that junk. Only snap on. I'd be more than happy to give you a tour of my shop but my parents have there cars parked in it right now. But as soon as they leave for work I'll be out there making dreams come true.
@@powellmachineinc BOY, Daniel, u sure get the gammut of the uninformed/affluent folk.....i've built 10 sec NA Engines myself, and have PLENTY of Craftsman screwdrives i use......the brand is NON SEQUITOR if the person behind the screwdriver is intellectually challenged!!
Step one remove Holley Step two install Edelbrock Step three don't f with it, because it is tuned better than you will ever get it. Step four buy the needle and jet kit because you're going to f with it. At least read the directions. Step five you change the needles to make your AFR number read one point different. And no I'm not discounting your knowledge or experience on these carburetors. I have literally swapped out a customers Holley out for an Edelbrock without them knowing. Had them drive it... They return with glowing reviews. Some get pissed off, some just want a result. I tend to have result oriented people in my circles.
![[UA] NAVI проти G2 Esports | Blast Premier Fall Final](http://i.ytimg.com/vi/QWlIm4FGESQ/mqdefault.jpg)
It is pretty modest to say you are not a guru but a novice. Sir you have a wealth of knowledge. Thanks for sharing
It's my pleasure
Mr. Powell, I truly believe what you are supplying to the UA-cam community is just invaluable to so many people, this 66 year old gear head can attest.☺️Like yourself, I came up through the school of “tweak it until you get it”. As a dyed in the wool Mopar fanatic, I can say wholeheartedly that what you are teaching the masses is the rules of universal law that are applicable to all. I campaigned the “Sixpack” cars for years and I learned a lot through trial and error…And a vacuum gauge!
I can tune the dog squash out of those 2300’s any more and I even supported the hobby, albeit briefly, with my own design of outboard carb idle screws and a close-quarters adjusting tool that many have used in the past years successfully. Sorry, I digress.
One thing I am glad you mentioned is the boosters. Those things, the fuel will creep out of to compensate for poor idle with low engine vacuum as well, which is what I would experience, especially with the big cams that I do.
Here again, you touched on it by drilling the butterflies and changing to a lower numerical PV. I also tune this area with idle bleeds as well.
Holley carbs are so much more forgiving as there are several different areas that work in conjunction which help the neighboring fuel transitional period with their superior design. Thank you so much for this insightful series. 🫡🫡
Absolutely, I enjoy hearing other's stories!
A 1980 tuneup was on a 1966-1977, so factory stuff was dust out, on a “Sun” machine, repair pivots, replace vacuum advance if needed, points filed for good ground. Condenser are used to allow current a place to go after points opened. Unplug vacuum from intake signal at carb, set to 10 degrees, pull out dial advance timing light, watch springs open, vacuum advance add (Note: 2:1 ratio, so 8 degrees at distributor is 16 at crank), total 34-36 degrees at 2,500 RPM, 4-gas in tail pipe, +/- 1ppm HC, 0.5 +/- CO, 19% O2, in-clamp air pump, check HC warm at idle with propane enrichment tool-canister-flow valve, PVC, fluids, tire pressure + spare. Test drive. Tune done w/new plugs, air filter if needed, trans/diff fluids and park it. Pays 1.5 hrs.
1980 tech flat rate @ dealer-$6.90. Aftermarket shop $11.00
Great info on Holley carbs. Now, 2024 the Holley group owns 70+ companies! Google it.
My gauge went super rich just as you described.
I went 28s front and rears and the results in my instance was night and day.
Had 31s front n rears previously.
Yep
Spot on the timing, the engine likes that advanced timing. The vacuum advance helps the mileage and helps keep the plugs clean. Great vid.
Right on
Removes all the extra fuel going in the engine that washes down the cylinder walls too.
A couple of comments, Holley makes anti-pullover discharge nozzles that can fix the issue you described. Regarding drilling the front butterflies, sometimes you can adjust the secondary throttle shaft stop screw 1/8 to 1/4 turn open, and crack those butterflies open a little more and achieve the same fix, allowing the primary butterflies to close and keep them below the transfer slot, but you can't go too far on the secondary stop screw and get out of their idle circuit. It's worth a try before drilling holes in the primaries. Good videos, hope they help folks!
The anti pullover nozzle did not cure the problem
@@powellmachineinc , interesting. Sounds like a vibration/frequency issue. We use 2.3 Fords in a marine application. At wot, 5600 rpm the engines would develop a surge. Kept thinking it was fuel related and couldn't find anything wrong. Finally put a timing light on the engine and saw the timing would retard 15 degrees then jump back up to 32 degrees once the rpms dropped. As soon as it got back to 5600, the timing would retard again, kept happening over and over. Turns out the fly weights in the Mallory distributor were bouncing off of the stops due to the engine's frequency/vibrations at 5600. Distributor checked fine spinning it in a Sun machine. Had to change weights, springs and the stop location to get the advance mechanism in another frequency range. Live and learn, never give up.
An anti pullover squirter won't fix the problem on a 4 cylinder ford engine, been there, done that and got the t-shirt! I think the little umbrella check that let's fuel into the pump from the bowl is vibrating and becomes a pump. I had this same situation and fixed it with an old fuel bowl with a captured ball check in it.
I helped a friend this past week sort out his Holley 850 on a stroker small block Mopar. It had an off idle bog. It never coughed back through the carb when bogging. He tried a lot of different things only to find out that the metering block wasn't drilled properly for the idle transfer slot. It took three of us and about 20 hours to determine what the problem was. He's 4 states away and he was able to enlist his local race engine builder's help. Talk about a challenge to find.
We had 1 with no transfer slot machined in the base plate
@@powellmachineinc I have one where you can't get the transfer slot to show up under the plates unless you really open the blades. They just aren't long enough--850 mechanical QF
Hell of a series Daniel, thanks.
Glad you enjoy it!
I've done the old school go pro riding on top of the engine myself. No one was injured, was able to see exactly what was going on!
Back then we did even have a cell phone, much less a go pro
Thank you so much. I certainly hope people will listen to what you're saying because it's extremely clear and that you know what you're doing. I've been tinkering with this stuff since the late '80s and it took me a long time to find out a lot of this information. Still learning things I did not realize the float level had that kind of impact. The manifold vacuum and vacuum advance for anything you drive on the street is absolutely critical. Most GM distributors pre-pollution control ran 12 to 16° additional vacuum advance at the crank and I have found that to be right for most applications.
Good point!, I'm definitely a novice, but we have picked up a few things over the last 25 year's
I learned a very long time ago to send my carbs to an expert so they will be right for the build. Next time I will be sending them to you.
I'm definitely not a carb expert, but I appreciate that
Call me hardheaded, but I do like figuring these things out as best I can, noting that a metering block is an interface module: one side brings fuel, the other air - and the air helps manage the fuel. One of the odd things about emulsions is that [to a point] sizing them up can deliver more fuel to the boosters because there is less mass to lift [being aerated] - volume delivered can accelerate for the same signal. Air bleeds primarily dictate how much signal is needed for mains [booster] to come on. Regarding emulsions, the lower they are, the more signal at the booster is needed to start air introduction/lift fuel. Some of the craziness of the past two decades began with some magazine inspired articles about resizing air bleeds... which is probably the dead last thing to tweak in most cases, but it can happen. Holley got most their stuff right, and modern improvements are mainly float bowl design, needle & seat, and booster design/location. It does appear that boosters being just a bit lower in the venturi bore is a general improvement regarding fuel shear and signal response vs older designs - base of the booster being roughly midpoint. I'm not at all going to claim guru status... but just maybe read a little too much, alongside making classic mistakes years ago such as trying to tune my way out of needing a valve job. That, um, did not work by the way - valve runout was a disgustingly large number: maybe 0.006" or worse on five valves between both heads.
I didn’t know everything you shared with us but I completely understood what you said. Knowing what’s in a carb does not mean you understand how all the parts relate. Absolutely the best overall explanation I have personally ever heard. I especially appreciate the explanation of the relationships between air bleeds emulsion tubes and float level. Thank you!
Thank you for watching!
Thank you for explaining this stuff in a way that makes sense to my dumb as way of thinking. Great videos, Randy
Our pleasure 🙏
So much learning. Thank you for your time.
My pleasure!
Thank you for sharing your experience!!
My pleasure!
Plenum volume, manifold temp, and ignition advance can make different engines stumble in odd ways.
Great video.
Great point!
no nonsense good info!
@@jimredding8315 ty!
Another excellent video of speaking hands on knowledge. I appreciate what you guys are doing here and the real life content you’re putting out. Keyboard warriors are just that. Those who can’t or haven’t and will not,are those who attempt to tell others where they’re going wrong. Excellent job with keeping your cool,you’re a better man than me for that. Appreciate you guys and and all you do.
Much appreciated!, we try hard!
A knowledgeable machinist /engine builder/carburetor tuner willing to share this information for free? I've got to bitch about this.....
Thank you Daniel for the blast of carb info. I am going to replay this vid so I can catch all of what you are pitching. I do carb rebuilds but I have to admit I do a" little alcohol".
Lol, definitely
Great info. Thank you. I now have a much better understanding of the emulsion circuit. I just purchased 2 used holley 750 hps to put on my tunnel ram on my boat. Engine is oval port solid roller 427. Both were out to lunch so looked up the factory calibration and i am starting with that.
Glad it helped
keep em comin!!! This is good stuff! Giving me some things to look at on carb. Thanks for sharing!
More to come!
This guy is intelligent listen up .
Well.... my wife may disagree, but I appreciate the vote
nice tips. I hope your cams kick some ass in the eric wiengartner cam contest.
@michaelmaher4328 thank you, we really appreciate that 🙏
Respectfully of course, and I will gladly stand corrected if shown to be in error, but as an auto service student in the early 80's, I believe we were taught that ported vacuum was used beginning with the early efforts to clean up emissions at idle by leaving the timing un-advanced. One other thought was that mashing the throttle from idle meant vacuum advance was lost which in some cases produced a stumble. Please keep in mind that I am referring to stock engines, not modified stuff. Thank you for your excellent vids and info!!
Correct. Ported vacuum was used to make the engine rot hot as shit at idle to lower emissions by keeping the exhaust much hotter than normal. (basically overly retarded ignition so there were raw flames in the manifolds). On engines with parasitic air pumps, the extra fresh air could continue the burning process in the exhaust pipe because there's plenty of unburnt air and fuel in there due to the retarded tune (and lowering your gas mileage doing it).
If you get an OLD paper repair manual you can look at the vacuum MESS of lines going to the carb, manifold and distributor. They'd have a thermal switch usually on the thermostat housing.
That switch would see the car running hot in still traffic and switch the distributor over to manifold vacuum to avoid a meltdown. When that happens, the car would rev up causing the fan to spin faster and make the timing closer to where it should be all the time. By not running retarded as hell, the engine could cool off because it wouldn't intentionally be boiling the coolant around the exhaust ports anymore.
I'm having some trouble getting mine set up and you gave me some information other people do not know. You need to talk more on the holleys.
There's another episode coming
Nicely done, learned tons. If you had a Patreon account, I would be inclined to send a couple of dollars a month. UA-cam you only get half I believe, but I don't see the THANKS button to give here either. You should get paid for your work
Wow, thank you!
Hi 1976 here again. Keep the answer"s coming, really good answers.
Ty!
A small group spring works to keep it on seat too .I road on a motor when things were cutting butt in the 70s too .
Definitely
It's about to get real interesting for me. Out side of what you have covered so far. I just don't have any knowledge of, but am very interested in. Thanks for the refresher.
I haven't thought about this stuff for quite some time. You've got my head in gear. Ha!
Excellent!
Very good information with this video. You have obviously had many experiences with Holly carburetors. I personally was never a big fan of Holly carburetors but I think it was due to people buying a Holly that was way to big for their stock engine and then bring it to me wondering why they have lost power and using more fuel 😂😂
Thank, we appreciate you watching!
Really enjoying this series.
Ty
nice show mate very informative and thanks for sharing your skills and knowledge keep the good work up perfect tutoring skills executed perfectly you would make a brilliant automotive education teacher when you get to old for picking up heavy engines and cyl heads, here in australia we call them tafe teacher (technical and further education)
Much appreciated, ty for watching
Very good information
Thanks
great video thanks for sharing i also always run vacuum advance how much advance depends on so many things just have to in my opinion go up and down until engine is happy. we call the boosters drop boosters in southeast Alabama. i have a pile of 50cc pumps i have pulled off and at one time thought everyone needed one until i learned better.
Analyzing someones so called carb issue is like taking the bull by the horns. What people need to realize is so many things affect carb adjustments, etc. Tall gears, heavy vehicles, cast iron manifolds, too much cam. The list goes on. I always recommend an O2 censor and especially a vacuum gauge. Especially the latter for carbs with a power valve. Great video!
Thank you! Very educational. Maybe some talk on carb spacers if you have time. Perhaps when to use 5/8” vs 1” in circle track applications.
Very good stuff. Great video with great info. Thank you.
That drilling the throttle for a big cam was in the Holley HP books in the late 70's. Yet people look at you like your crazy.
Yep
got a neighbor with a semi built street motor.holly double pumper stumbleing when secoundary opens up.suspect timeing and or fuel mix screws.gona put a vacuum gauge to set screws an check timeing.maybe check that rear float adjustment.burning rich.thinking the same way.thanks daniel.most people dont have a clue
i gota tell ya Daniel...u r dead on the money...when u said..u cant beat a GM HEI disturibtor...!..i live'd it first hand..!..the only issue that they had...was over 8000 rpm the kv's would drop off..mallory made a power cell...u just mount it on the firewall & connect it inbetween the brown wire run'n from the distribetor to the coil....and wala...no kv drop over 8000 rpm...!..holy reliable...!..& a dame site cheaper than (@ the time) an accel distributor...&..car ran the same time with either distributor...!..Thanks for the carb serious....!..great idea...!.p.s. of course that was shimed & the lightest springs in the stock HEI...!..no plug foul'n, misfire'n,break'n up...could NOT tell the differance..!..
Definitely
Lol .. holding on to the roll cage story. Love it.
Nice. Makes sense now. Chrysler/ Dodge run ported vacuum and Chevy runs manifold vacuum. I loved the Mopars and thought ported vacuum made sense. Not anymore! No wonder i always had problems with pinging! I was essentially adding timing under load when i should have been pulling timing out. That's what happens when you try to learn how to modify smog era junk with no experience of what worked before then. All the Chilton books i have or had didn't help nothin'. Now i know i could have dialed in 36 degrees total and let the idle timing land where it is; and if the vacuum advance became a problem just unplug it; yeah, i wish i had a time machine and go back 40 years! Damn!
I've been told a low stall and or heavy vehicle will usually require more squirter and a came adjustment.
The more load off idle, the more demand for fuel squirter and cam lift and or duration. Until the signal in the venturi starts pulling fuel and the load demand lessons.
Agree
Thats true. I've had a problem with that before.
Really good information on the emulsion wells.
Can you share more information on the air bleeds? The reason some people use ported vacuum is they have low advance at idle and as the throttle is opened it adds timing and makes the engine feel more responsive. With more initial and less in the curve for the same total manifold is better, just like you explained
Definitely
Oh boy the timed vacuum police will be coming for you now! Great video I’m gunna put the emulsion info to good use thanks.
Yeah, there's a whole bunch of 'experts' and 'gurus' out there that don't understand how things actually work. But REALLY think they do.
Same as blocking off EGR, you have to tune the timing curve to work with your now 'more correct' tune.
Ported vacuum was just a government mandated crutch to make an engine run like crap at idle to lower emissions.
The vacuum advance part of the discussion interesting. Between ported and manifold, I didn't think the actual vacuum signal was any different with any specific load when comparing the two. Just not present at idle with ported/timed. Only reason I say that is you mentioned potentially having too much vacuum advance under a load using the timed port. On my Ford big block, I measure like 18 inches at the manifold and same at the timed, just only once the throttle plates open enough. I thought under a load, the signal would drop to the same regardless of which side you have the canister hooked to. I dunno. This carb series is really interesting and I appreciate you taking time to go through it.
That’s exactly right, once the primary throttle blades are cracked open a small amount the ported/timed hole in the base plate is uncovered and subjected to manifold vacuum also, so they would be the same from that point on. At wide open throttle (WOT), the manifold vacuum would fall to basically zero, and so would the ported/timed vacuum. The myth that ported/timed vacuum increases at high rpm and WOT needs to stop. Where is this magical ported vacuum source coming from at WOT?
You touched on power valves and wot in drag application. Was hoping to get more info. Thanks great videos
Will try to address that next episode
Awesome video.
Thanks for the visit
Love the videos
Ty!
I have been tuning and rebuilding Holley’s for over 50 years and I get pretty good results. The thing I wish someone would come out with is tuning multiple carbs mainly two carbs on a blown application. I have a 871 blown 406 dart engine. I have been fighting with the carb adjustment for years. I can’t find any instruction on how to tune a blown application with two 4 barrels.
Thank you!!
You're welcome!
I think ported vacuum (for ignition timing) is mostly an emissions thing that normally need to be accompanied by a functional EGR system to be of any benefit.
Talk about, " keeping one's eye on the job "!
The old Holley trick kits had so many tuning parts but I don't think they even make those kits now .
Yep
The only application for ported vacuum advance is for pollution control in the '70s particularly pre Cadillac converter. It caused the motor to run hot at idle and still be firing charge in the exhaust to emulate a catalytic converter. No engine is ever going to run right like that
Possible power valve inch lbs of vacuum tuning can help tune in that area (if you are running a power valve)
At that point vacuum is at its highest, the pv is off
PSI - NEEDLE & SEAT REQUIREMENTS? Can you speak on the Minimum & Max pressures required for each size of needle & seats?
.097 vs .110 vs .120 vs .130
Each requires something a little different but what is that PSI requirement? Is it listed somewhere?
And thanks for putting your knowledge & experience out there for us.
With a .110 I always just set it at 7psi and left it at that but it would be nice to know more about the actual requirements.
Don’t you think he is in the transition slot area of the fuel curve…Doubt the booster is even active yet especially if straight leg booster. My humble opinion.
Very possible, I bet the booster is flowing, butI do think a IFR change may be the answer after I think about it further, definitely a good suggestion and we will go over that next video
hey MR powell im new to your channel and really like the way you teach about all aspects of whatever your doing thumbs up ||| I got a issue with a small block chevy 355 that for some unknown reason NOTHING has changed or fixed the problem its very strange condition happening when your at cruise speed (2200 --2700 ) engine turns headers red and engine temp rises quickly all indications are a lean condition BUT installed wide band and it shows rich 10.43and plugs show rich have jetted down to .064 ---- 4.5 power valve timing is locked now at 34 deg. tried SEVERAL different things all to no avail IF your up for a challenge please get back to me thanks JEFF
@jeffwarwick6124 what did the afr gaige say when u changed jets
Thanks for your response. The wideband read at 11.22 after the jet change should be Lane at this point, but still showing rich I have been as low as 54s on the front side trying to limit down to no avail so far have tried four different carbs, 5 different ignition systems, change valve adjudgmen imaginable timing locked with vacuum advance, etc. in all positions@@powellmachineinc
@@powellmachineinc
Thanks for responding Mr. Powell I hope I’m not sending multiple responses. If possible I could call you and explain what all I have done and what all I have tried and see if you have any suggestions or if you would like to call me I would gladly give you my number. Thanks, Jeff.
The aft read 11.22 I have been as low as 54 jets still running rich
Air Bleeds. Could you talk more about them please? What I know of air bleeds in the fuel circuit, is that the make the fuel flow more, richer you could say. Air bleeds make the fuel flow more by lowering the surface tension of the gasoline on the passages in the carburetor. There is another example of this, when hydroelectric dam engineers introduce bleed air into the penstock tubes that feed the turbines. It lowers the surface tension of the water, and more water flows, and the dam generates more electricity. Anyhow, I don't think many people actually know what air bleeds do in a carburetor. Could you please explain how they can be used to tune a Holley? Thanks. ---Doozer
Would love to hear your tuning thoughts on the Qjet carburator.
Turning motors is one thing, but, if you can run some EGR... When warm, vac advance initiates EGR and combustion chamber contents are burning with more heat and lower temperature.
Great video. Thank you much. So you were saying annular boosters flow too much fuel? Is that what you think? My 3310 Holley worked pretty good with annular boosters but it did use a lot of fuel. Maybe too much.
It's progressive, they get richer as airflow increases.
@@powellmachineinc Makes sense. Got it! Thanks for your reply!
It went to 11.22 the carb is a proform 750. 4 corner idle adjustment front mixture screws make very little if any difference transfer slots are pretty much closed setting idle with rear. Have been as low as 58 on jets but still rich. Tried 4 different carbs and 5 different ignition systems it’s driving me nuts lol. Thanks in advance. I’ve tried any and everything trying too correct it idk thanks Jeff
Something doesn't add up and it sounds exactly like a vacuum leak
I know I just can’t find it. Ran a internal vacuum leak test and found it had 1 in lb blow by. I’ve tried 4 different carbs etc. nothing has worked. Thanks for your time and help. Jeff.
Ps would like to discuss this further with you if you’re interested in helping me try to figure this crazy thing out. ??
Finally got this thing lean drilled holes in base plate. Still not much difference in idle screws on primary went with 64 jets front and rear still runs rich at idle and lean at cruise speed
@jeffwarwick6124 I had a thought, what's the cranking compression? Also did you confirm the intake centerline?
Cranking compression is 175-180. Rechecked cam centerline is within a half a degree. Still searching finally got it lean at cruise but it’s rich at idle. Trying to find that line
There is a bit of truth to timing messing with your tuning of the carb. You obviously have a good idea of what's doing what. Just like anything else you are modifying it's a whole package not just a Facebook marketplace shopping list. I just saw tkms video on valve springs being a drop in. People will always think they are making a better mousetrap but not optimizing the package to work in your application.
Yes, it's all relative, I say in the video
What causes you to be on the main jet at idle? Booster looks like it is "leaking" from mild fuel flow... Runs great, afr is fine... Too much throttle blade angle? It doesn't really seem like it is too much but idk...
High float will do it or a leaking n&s
How do you get the motor to crank up correctly with a locked out distributor
It's not a problem you can watch the 604 crate engine we built crank with 36 degrees no issues
I have an 11:1, 421 SBC locked out at 34* (AFR heads). With any decent size cam, they'll crank over easily hot or cold. Great video !!!
I bought a Holley a guy, it came off a 604 late model engine. It’s got adjustable air bleeds, could you go over those? What does what when you change them. It has 2 per barrel. I have seen some carbs with 3 in catalogs? Just curious about those. I’m getting ready to swap a carb on my 95 5.0 and need all the help I can get.
checking on two things. 1. fuel shouldn't be coming out of accelerator noozles except when pump is pushing it out, right? 2. is there a carbs 101 ep#3?
Correct, and #3 is coming, just busy
How do you install a different booster? Do you use a swaging tool from BLP to expand the short tube in the body or do you have a different method?
Yes, we flare the booster in place
Do you have any experience tuning a pair of dominators?
Yes
Could you touch on some of that on your next tuning video?
At 31:30, Are you saying that having your distributor vacuum advance connected to a ported/timed vacuum source will ADD additional timing at wide open throttle? Engine vacuum, whether manifold, or ported/timed, will be a zero, (or very close to it), at wide open throttle, right?
No, the port on the carb will increase with rpm, that's the issue
Wouldn’t off idle rich lean be more idle fuel restrictors pass trough transfer slot
He said idle afr's were good, absolutely could try several things, maybe even idle air bleed may solve it
Ok just for my own knowledge idle o2 is set by the mixture screws but off idle it can go rich or lean cause the only thing setting the mixture is the idle fuel restrictor. So does a guy lower float level, open main bleed .001 or .002 , change idle restrictor. I would be nice to somehow have a throttle position sensor to see where the throttle is compared to what circuit is actually causing the issue using a wide band. Sorry for long rant
Nice job. The people that understand carb. are disappearing.
Unfortunately
Are you doing another video for tuning?
Yes, probably 1 or 2 more
I can tell your no real motor guy because you've got one of those crapy Craftsman screwdrivers. Nobody uses that junk. Only snap on. I'd be more than happy to give you a tour of my shop but my parents have there cars parked in it right now. But as soon as they leave for work I'll be out there making dreams come true.
I have no doubt! Keep the dream alive! (When mommy will allow you outside)
@@powellmachineinc BOY, Daniel, u sure get the gammut of the uninformed/affluent folk.....i've built 10 sec NA Engines myself, and have PLENTY of Craftsman screwdrives i use......the brand is NON SEQUITOR if the person behind the screwdriver is intellectually challenged!!
Nothing wrong with craftsman tools. I built my nine second Mustang using craftsman and HarborFreight tools.
@@mikeyb1835 yep, that was my poin Mikey....TY sir!!!......
Step one remove Holley
Step two install Edelbrock
Step three don't f with it, because it is tuned better than you will ever get it.
Step four buy the needle and jet kit because you're going to f with it. At least read the directions.
Step five you change the needles to make your AFR number read one point different.
And no I'm not discounting your knowledge or experience on these carburetors. I have literally swapped out a customers Holley out for an Edelbrock without them knowing. Had them drive it... They return with glowing reviews. Some get pissed off, some just want a result. I tend to have result oriented people in my circles.