[72chevelle_muscle]

I have already purchased everything for my next engine which will be a 383. I will probably never dyno, what horsepower and torque will it make? 383 sbc, 9.5 to 1 cr,vortech heads, stock size valves, GM roller hot cam, comp roller rockers, edelbrock dual plane intake, holley 670 or 770, stock HEI, 1 5/8 headers. I am still undecided on what carb is best.. Car will never see anything passed 5500 RPM, mostly street driven.

 

[rustbucket79]

670 street avenger would be my choice.

 

[SWHEATON]

If it has a mild cam & you say it will never be twisted past 5,500rpm,then the 670cfm is fine.

scott

 

[Aaron]

If it is a auto, I suggest the 770 or a good old 3310 Holley 750. If it is a stick car, a good old 650 DP or 750 DP.

 

[wildman926]

if It Is A Auto, I Suggest The 770 Or A Good Old 3310 Holley 750. If It Is A Stick Car, A Good Old 650 Dp Or 750 Dp.

X2!!

 

[Dave427]

I would use a 770 also, the 670 is a bit small.

Dave

 

[Schurkey]

Baseline carb CFM is really easy.

RPM X CID / 3456 X VE X Manifold efficiency = Baseline CFM

So, 5,500 X 383 = 2,106,500

2,106,500 / 3456 = 610 (where 3456 is a constant that takes into account the number of cubic inches in a cubic foot; and the fact that your engine is a 4-stroke.)

610 X .85 = 518 (where .85 is a guess at your volumetric efficiency.)

518 X 1.3 = 674 carb CFM (where 1.3 is a guess at the efficiency of your intake manifold.)

A 670 cfm carb is nearly perfect for your application. I'm not saying the Holley 670 Street Avenger is "THE" perfect carb, but it's the right size.

A bigger carb could work just fine; but I wouldn't expect you'd gain power. On the other hand, if that was my car, it'd have an electric-choke 750 Q-jet mounted on top long before I'd spring for a Holley.

 

[dirtlips408]

My father in laws Camaro had the exact same 383 combo. Its works really good. He had a 750 Edelbrock on it and it worked really good on the street. But if it were mine like others have said.....3310 or 770SA.

 

[BigRed-L72]

A great but often overlooked carb that works very well on 383-406 `s is a Holley 9381.
It`s an 830 annular and can be had for about $420 new.

 

[SWHEATON]

FYI,just for ha ha's i ran his 383 as mildly modified with a 5500rpm max thru Holley's NEW carb estimater and it came up with 600cfm-670 cfm as the rec carb fsize for best performance,but i would have to say i would not go less then 670cfm even on a mild 383.

But i have to also aggree that a "hot 383 " with lrg cam & good breathing intake/heads/exhuast could easily use more carb like 750-770cfm & maybe even 80cmf for a real hot setup but the 670cfm would be just fine for a "mild street 383" which is the key point.

You have to remember not everyone is looking for max output/perf like when racing esp when they already stated up front it's a mild 383 that will never see past 5,500 rpm . So this 383 is more of a moderate perf lvl for street use motor and not max effort that needs more carb IMHO & i guess to be fair also Holley's opinion too since i ran it through thier NEW carb estimater.(LOL!!!!)

Scott

 

[Autoengineer]

You should check out the August edition of Car Craft. They built pretty much what you described...383, vortech heads, GM hot cam. They got 412 hp and 466lb*ft trq.

 

[SWHEATON]

Nice combo at 412 hp and 466lb*ft trq,should be a fun setup.

Scott

 

[72chevelle_muscle]

thanks for all of the advice? I will probably go holley 670.

 

[webfoot]

I have a holley 650 DP on my 383, it really snorts. Probably need to step it up a notch though.