WHAT SIZE CARB

[andrew mangrum]

I was wondering if someone could help me I have a 91 stang that was fuel injection and now is carb it has a 331 stroker right now it has a holley 750 and its way to much for the engine any suggestions on what size would be good I would appreciate it

[12Pack]

650

[RGR]

Quote: Originally Posted by 12Pack 650

Demon 650 would be perfect for it probably.
Demon carbs seem to have better low end than a Holley.
If you want cheap then try a Holley 600 Vacuum Secondary, or a
Holley 650 Double Pumper. Or just get the jetting kits for your 750
and make it work. If it is a vacuum secondary you can make it respond
fairly well on even a 5.0 sized engine. It's all in the tune. Somewhere
out there you can find a jetting chart (starting point) for your setup,
and that will be darn close and it will run good. Good Luck Andrew!

PS: A generic Holley 600 (4160 I think) would probably be really good
since most of them are setup for a mild 350 ch*vy which is about right
for a good 331 stroker. A 4160 for the Ford 5.0 would be a good economy
carb for your 331, getting better mileage but still make good power.

[SilentNoise]

On a 331 I wouldn't go as low as a 600 because you may risk running a little lean in the higher RPMs. With a 650 you'd be safe and have a little extra for a comfort zone.

Here's the calculation used to figure out carb sizing: CI x RPM x VE / 3456 = CFM

When it comes to volumetric efficiency, a .9 VE number represents a pretty good combination (usually a good number to use on a stock motor) and a 1.1 VE number pretty much represents an all out assault on the engine block's stress handling capabilities.

I'm not sure what your red line is at, but I'm just going to guess something like 6500 for the hell of it, and I'll go with a 1.0 VE since it is a stroker and puts more pressure on the block, but isn't a monster:

331 x 6500 x 1 / 3456 = 622cfm............ so a 650 would be good.

[RGR]

Quote: Originally Posted by SilentNoise On a 331 I wouldn't go as low as a 600 because you may risk running a little lean in the higher RPMs. With a 650 you'd be safe and have a little extra for a comfort zone... ...331 x 6500 x 1 / 3456 = 622cfm............ so a 650 would be good.

A 600 will not lean it out at high RPM, any off-the-shelfer will be rich, guaranteed.

All the 600 could do is generate a slightly higher vacuum @ WOT meaning it's
just a tiny bit small. 600 for economy and good power, 650 for max WOT power.

The 650 also has better designed boosters, making better HP. But it's about twice the money as a generic 600 Holley too.