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