NEVER put a 750 on a 318........

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The 'math' says to run a 850 on my 383 stroker 360. The 'math' is wrong. It only likes a 1050 Dominator.
 
You can run a big carb on a small cube engine if it's a Carter/Edelbrock or a Holley vac. secondary, or a Thermoquad. Your stock Teen may not like a 850 double pumper, dual inlet Holley with 50 cc Reo pumps. Now take the dual quads for instance, you run off of 2 or 4 barrels depending on your linkage on the dual quads. I don't know the specs, but the primaries of a 600 cfm carb are 300cfm or less. Even if your linkage is not progressive, a teen should be able to handle 600 cfm. Kick the secondary's in and the air valves will only give the engine what it needs. The 6 packs run off the center 2 barrel. Depending on which set up, they are what 390 cfm? The outboard carbs are vacuum operated so they only give the engine what it needs as well but you guys know all this. It's like preaching to the choir! LOL
 
I have run 750 DP Holleys on 318's with stock converter, stock 318 heads, stock short block but just a MP cam. I'm not saying it was "needed", just say'n it worked great.
 
toolmanmike said:
You can run a big carb on a small cube engine if it's a Carter/Edelbrock or a Holley vac. secondary, or a Thermoquad. Your stock Teen may not like a 850 double pumper, dual inlet Holley with 50 cc Reo pumps. Now take the dual quads for instance, you run off of 2 or 4 barrels depending on your linkage on the dual quads. I don't know the specs, but the primaries of a 600 cfm carb are 300cfm or less. Even if your linkage is not progressive, a teen should be able to handle 600 cfm. Kick the secondary's in and the air valves will only give the engine what it needs. The 6 packs run off the center 2 barrel. Depending on which set up, they are what 390 cfm? The outboard carbs are vacuum operated so they only give the engine what it needs as well but you guys know all this. It's like preaching to the choir! LOL
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I disagree. IMO the VS Holley is worthless. And a properly tuned Holley will make more power and not give up anything to any Carterbrock, QJ or TQ.

The biggest issue with the Holley and all the clones is all the misinformation, disinformation and downright ignorance of how any carb functions, let alone a Holley. Rivers of ink have been spilled writing books by different authors who all repeat the same crap. And then it gets handed down via magazine articles, forums and such.

I am amazed at how much time and effort people spend learning EFI, yet they didn’t spend 1% of that time learning carburation. I suggest it’s because for decades they have been told carb tuning is a “mystery” filled with voodoo and one must be adept in conjuring the spirts of carb tuners long past. And that isn’t the case at all.

The other issue is this, and I point this out because you suggested the VS as an alternative as does David Vizard and a host of others.

All of the carbs designed and built by Holley (and now the clones regardless of the name on the box it comes out of) that were “street” carbs had a very clean tune (for lack of a better term) that were far better suited to street use than the “universal” performance carbs they made and still make.

For example, if you went out and bought a brand new 3310 it has an entirely different tune in it than the same carb (4779) in a 750 double pumper. And it showed in all around driveability, fuel consumption, hot starting and even WOT.

The Holley, by design or engineering mistake all get rich as the RPM goes up at a far greater rate than other brands of carbs. It’s relatively common knowledge that a Holley is rich at idle, lean in the middle and fat up top most of the time.

All the “universal” performance Holley carbs come with a very fat tune on every circuit to begin with and they always had bigger jets than its street carb equivalent.


Had Holley and all the writers, tuners and such had taught even the most rudimentary principles of carburation rather than sit on the knowledge for whatever reason the end user could have made an educated decision when buying a carb rather than listening to the stooge behind the parts counter (who also was never trained in carburation) or relying on magazine articles and such to pick a carb.

Even the Holley charts used today to pick a carb are wrong. It’s no wonder the Holley is universally hated by those who never spent the time to understand carburation, even on the most basic level.

I never advise anyone to use a VS carb for anything. There are much better choices IF the end user is willing to learn, or pay someone to get the carb tuned.

EDIT: I forgot to mention that another issue is carb sizing using a dual plane intake verses a single plane intake. If you are using a DP intake and a 750 carb and you switch to a single plane and keep the same size carb, you will lose power below peak torque every time.

This is because the DP intake effectively cuts the carb size in half. The SP intake now is “seeing” all of the 750 carb while the DP intake only saw half of it.

The equivalent of this scenario would be removing the 750 from the DP and dropping on a 1500 CFM carb. You’d lose everywhere. No one would consider doing that, yet it happens all the time when switching from a DP to SP. And the intake manifold gets blamed.

It is horrible policy to buy a carb based on CFM. It should be based on venturi and throttle blade diameter.

And then we could discuss booster options that make the Holley much more tuneable than other carbs due to lack of parts. Some will claim the Carterbrock, QJ and TQ boosters are so good that you can’t improve on them. That’s just rediculous. A production booster was chosen for the broadest possible usage across the product line. The ability to zero in booster design and gain is a bug tuning capability that can’t or shouldn’t be ignored.
 
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Rat Bastid said:
I disagree. IMO the VS Holley is worthless. And a properly tuned Holley will make more power and not give up anything to any Carterbrock, QJ or TQ.

The biggest issue with the Holley and all the clones is all the misinformation, disinformation and downright ignorance of how any carb functions, let alone a Holley. Rivers of ink have been spilled writing books by different authors who all repeat the same crap. And then it gets handed down via magazine articles, forums and such.

I am amazed at how much time and effort people spend learning EFI, yet they didn’t spend 1% of that time learning carburation. I suggest it’s because for decades they have been told carb tuning is a “mystery” filled with voodoo and one must be adept in conjuring the spirts of carb tuners long past. And that isn’t the case at all.

The other issue is this, and I point this out because you suggested the VS as an alternative as does David Vizard and a host of others.

All of the carbs designed and built by Holley (and now the clones regardless of the name on the box it comes out of) that were “street” carbs had a very clean tune (for lack of a better term) that were far better suited to street use than the “universal” performance carbs they made and still make.

For example, if you went out and bought a brand new 3310 it has an entirely different tune in it than the same carb (4779) in a 750 double pumper. And it showed in all around driveability, fuel consumption, hot starting and even WOT.

The Holley, by design or engineering mistake all get rich as the RPM goes up at a far greater rate than other brands of carbs. It’s relatively common knowledge that a Holley is rich at idle, lean in the middle and fat up top most of the time.

All the “universal” performance Holley carbs come with a very fat tune on every circuit to begin with and they always had bigger jets than its street carb equivalent.


Had Holley and all the writers, tuners and such had taught even the most rudimentary principles of carburation rather than sit on the knowledge for whatever reason the end user could have made an educated decision when buying a carb rather than listening to the stooge behind the parts counter (who also was never trained in carburation) or relying on magazine articles and such to pick a carb.

Even the Holley charts used today to pick a carb are wrong. It’s no wonder the Holley is universally hated by those who never spent the time to understand carburation, even on the most basic level.

I never advise anyone to use a VS carb for anything. There are much better choices IF the end user is willing to learn, or pay someone to get the carb tuned.
Click to expand...
I'm not a fan of the VC carbs either.
 
Rat Bastid said:
I disagree. IMO the VS Holley is worthless. And a properly tuned Holley will make more power and not give up anything to any Carterbrock, QJ or TQ.

The biggest issue with the Holley and all the clones is all the misinformation, disinformation and downright ignorance of how any carb functions, let alone a Holley. Rivers of ink have been spilled writing books by different authors who all repeat the same crap. And then it gets handed down via magazine articles, forums and such.

I am amazed at how much time and effort people spend learning EFI, yet they didn’t spend 1% of that time learning carburation. I suggest it’s because for decades they have been told carb tuning is a “mystery” filled with voodoo and one must be adept in conjuring the spirts of carb tuners long past. And that isn’t the case at all.

The other issue is this, and I point this out because you suggested the VS as an alternative as does David Vizard and a host of others.

All of the carbs designed and built by Holley (and now the clones regardless of the name on the box it comes out of) that were “street” carbs had a very clean tune (for lack of a better term) that were far better suited to street use than the “universal” performance carbs they made and still make.

For example, if you went out and bought a brand new 3310 it has an entirely different tune in it than the same carb (4779) in a 750 double pumper. And it showed in all around driveability, fuel consumption, hot starting and even WOT.

The Holley, by design or engineering mistake all get rich as the RPM goes up at a far greater rate than other brands of carbs. It’s relatively common knowledge that a Holley is rich at idle, lean in the middle and fat up top most of the time.

All the “universal” performance Holley carbs come with a very fat tune on every circuit to begin with and they always had bigger jets than its street carb equivalent.


Had Holley and all the writers, tuners and such had taught even the most rudimentary principles of carburation rather than sit on the knowledge for whatever reason the end user could have made an educated decision when buying a carb rather than listening to the stooge behind the parts counter (who also was never trained in carburation) or relying on magazine articles and such to pick a carb.

Even the Holley charts used today to pick a carb are wrong. It’s no wonder the Holley is universally hated by those who never spent the time to understand carburation, even on the most basic level.

I never advise anyone to use a VS carb for anything. There are much better choices IF the end user is willing to learn, or pay someone to get the carb tuned.
Click to expand...
4779 ..... my favorite all around carb. It will run a mild 318 or a 10 second 440. Nobody that supports VS can explain why the 4779 on my Duster when it had 2.45 gears, stock converter, and stock exhaust manifolds, stock 360 heads, and a cam smaller than a factory 340 cam, cut a better 60 ft, ET, and MPH than the 770 VS or 600 eddy. That was a combo MADE for the "VS or 600 eddy", right ? Yet, the DP was the only carb to run it into the 13.9's and cut the best 60 ft time. And that was with the 10.5 PV.
 
Ah-I have a Holley 1050 3 barrel, thought I would put it on my 273 2 bbl engine. How do you think that would work?:rofl:
 
lemondana said:
Ah-I have a Holley 1050 3 barrel, thought I would put it on my 273 2 bbl engine. How do you think that would work?:rofl:
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That might be a little too big. Holley never figured out how to do the adjustable air valve thing. They were too busy selling vacuum secondary carbs and power valves. You should trade that Holley 3 barrel to me for a 400 cfm Holley. :rofl: I have run a 750 cfm 340 TQ on a 1967 273 2 barrel motor. Ran fine for what it was.
 
Rat Bastid said:
I disagree. IMO the VS Holley is worthless. And a properly tuned Holley will make more power and not give up anything to any Carterbrock, QJ or TQ.

The biggest issue with the Holley and all the clones is all the misinformation, disinformation and downright ignorance of how any carb functions, let alone a Holley. Rivers of ink have been spilled writing books by different authors who all repeat the same crap. And then it gets handed down via magazine articles, forums and such.

I am amazed at how much time and effort people spend learning EFI, yet they didn’t spend 1% of that time learning carburation. I suggest it’s because for decades they have been told carb tuning is a “mystery” filled with voodoo and one must be adept in conjuring the spirts of carb tuners long past. And that isn’t the case at all.

The other issue is this, and I point this out because you suggested the VS as an alternative as does David Vizard and a host of others.

All of the carbs designed and built by Holley (and now the clones regardless of the name on the box it comes out of) that were “street” carbs had a very clean tune (for lack of a better term) that were far better suited to street use than the “universal” performance carbs they made and still make.

For example, if you went out and bought a brand new 3310 it has an entirely different tune in it than the same carb (4779) in a 750 double pumper. And it showed in all around driveability, fuel consumption, hot starting and even WOT.

The Holley, by design or engineering mistake all get rich as the RPM goes up at a far greater rate than other brands of carbs. It’s relatively common knowledge that a Holley is rich at idle, lean in the middle and fat up top most of the time.

All the “universal” performance Holley carbs come with a very fat tune on every circuit to begin with and they always had bigger jets than its street carb equivalent.


Had Holley and all the writers, tuners and such had taught even the most rudimentary principles of carburation rather than sit on the knowledge for whatever reason the end user could have made an educated decision when buying a carb rather than listening to the stooge behind the parts counter (who also was never trained in carburation) or relying on magazine articles and such to pick a carb.

Even the Holley charts used today to pick a carb are wrong. It’s no wonder the Holley is universally hated by those who never spent the time to understand carburation, even on the most basic level.

I never advise anyone to use a VS carb for anything. There are much better choices IF the end user is willing to learn, or pay someone to get the carb tuned.

EDIT: I forgot to mention that another issue is carb sizing using a dual plane intake verses a single plane intake. If you are using a DP intake and a 750 carb and you switch to a single plane and keep the same size carb, you will lose power below peak torque every time.

This is because the DP intake effectively cuts the carb size in half. The SP intake now is “seeing” all of the 750 carb while the DP intake only saw half of it.

The equivalent of this scenario would be removing the 750 from the DP and dropping on a 1500 CFM carb. You’d lose everywhere. No one would consider doing that, yet it happens all the time when switching from a DP to SP. And the intake manifold gets blamed.

It is horrible policy to buy a carb based on CFM. It should be based on venturi and throttle blade diameter.

And then we could discuss booster options that make the Holley much more tuneable than other carbs due to lack of parts. Some will claim the Carterbrock, QJ and TQ boosters are so good that you can’t improve on them. That’s just rediculous. A production booster was chosen for the broadest possible usage across the product line. The ability to zero in booster design and gain is a bug tuning capability that can’t or shouldn’t be ignored.
Click to expand...

I got David Vizard's "How to Super Tune Holley Carburetors" book a couple years ago and it really opened my eyes on the finer details of not just how carburetors work but how they interact with different engine combos. Pretty much all of what you're saying is in line with what I've read in his book. You can't expect an OOTB carb that's as tune-able as a Holley to work anywhere near its max potential without knowing how to properly set it up and tune it for your specific combo, not just engine but the entire drivetrain and vehicle. And you can't approach them with the same mindset as Carter-based carbs like TQ, AFB etc. they just work differently.
 
MopaR&D said:
And you can't approach them with the same mindset as Carter-based carbs like TQ, AFB etc. they just work differently.
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I couldn't tune my Holley 750 DP worth a piss after some engine work, I lost track of what I did and slapped an Edelbrock on so I could drive the thing. I still haven't taken the time to learn, but I may down the road. I can always bring it to my buddy who just retired, he knows what he's doing, and I just have to bring some beer!
 
LocuMob said:
I couldn't tune my Holley 750 DP worth a piss after some engine work, I lost track of what I did and slapped an Edelbrock on so I could drive the thing. I still haven't taken the time to learn, but I may down the road. I can always bring it to my buddy who just retired, he knows what he's doing, and I just have to bring some beer!
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Beer always makes the carb guy happy.
 
I think why many would think a 750 is way over carbing on a small displacement especially stock ish is people slapping on a 750 probably tuned for a larger more aggressive engine and they never tuned it to work.
 
273 said:
I think why many would think a 750 is way over carbing on a small displacement especially stock ish is people slapping on a 750 probably tuned for a larger more aggressive engine and they never tuned it to work.
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I see no reason or gain using a 750, a properly tuned 650 dp would be perfect for most 318's. imo
 
375 cfm x 2
So primary cruising is essentially like a 375cfm 2 brl.

But hey lets not come back with a generalized take away, we know small primaries mix at a greater velocity and work.
Small port heads or small 280 cfm primary thermoquads... we can make a lot of things work... and we can stand in both lanes if the combo is edgy or intended for rpms that will use that larger cfm carburetor.
Booster design, secondary actuation type, tune, weight , gear. Rpms..
It would be naive to say or use a generalized example that paints this picture of a stock 318 with a 750...when it's not.
 
fishmens67 said:
I see no reason or gain using a 750, a properly tuned 650 dp would be perfect for most 318's. imo
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Personally around 350-400 hp I’d think about stepping up to a 750 no matter the the cid.

under 350 hp definitely 600-650 cfm, would find it hard to find a combo where I’d go less.

But I don’t think 750 is need for under 350. -400 hp but don’t really think it’s over carbing either
 
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thesiren74 said:
Not many ones are salvageable getting scarce.
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If you are talking about Thermo-Quads, you might be right. I have had mine since the 70's and I used to buy good ones up for years. I still see quite a few at swap meets though. You just have to pay more now, since people have realized the value.
 
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