I just had my engine built and not sure what SA I need, I was told 670 by one machinist and 770 by another at the shop.
My set-up is:
350 bored .040 over
Vortec heads reworked ( new springs, valve job, roller rockers)
Comp XE 262 cam
speed pro 10 to 1 compression coated pistons
shorty headers
performer RPM intake
700r4 with 3.42 ( no stall) can get one.

Any advice would be great.

a 650dp would be fine.. your cam is tooo small for a 750

With that gear ratio and auto trans I would go with a Holley 650 VS...why does everyone always suggest a double pumper on our heavy cars with auto transmissions? Unless the only speeds you are going to go is full throttle or stop I myself have learned to stay away from double pumpers.

If you're going to be snow plowing or towing, get a vacuum secondary carb like the Street Avenger.

If you're after performance, get a double pumper.

I thought with an automatic I needed VS? My other question is will a 650 still be enough if I eventually get a one or two size bigger cam and a stall?

VS is a "safe" recommendation for automatics. It certainly is not a "need".

I have a DP on both cars in the sig.

http://www.holley.com/data/TechServi...Carburetor.pdf

You need to be between the two charts - at least as big as the size recommended by the first, and no bigger than the one recommended by the second.

A 650 DP meets your needs.

You don't need VS with an auto tranny. You should have a vacuum advance on the distributor though. If you have emissions equip on there it may be hard to do. With your compression ratio a 650 double pumper should work great...if you are looking at more high end vs drag you can go bigger. But a 650 DP with a hotter cam than what you have is just going to shave time off that 1/4. Check out the Holley website, you can compare carbs based on your setup. Sounds like your off to a great start! Your running a really close setup to mine. Keep us posted...

would a Holley 700 double pumper be ok? model 4778?

i would say you need a bigger cam before you need the 700dp.. you can have the bigger carb, but the cam is too small to take advantage of the flow..

do you know the rest of your cam specs?? lift? duration @ .050" lift? LSA? rpm range? or just tell me if its a hydro cam or roller or what??

It's hydraulic Gross Valve Lift0.462 0.469 Duration At 0.006 Tappet Lift262 270



lobe separation 110

It's going to be more fuel than the motor needs, resulting in poor acceleration, weaker torque, but an increase in top end. It's hard to break a hundred with all the po po out there these days...I keep mine quick in the 1/4, who cares after that. Nascar runs anywhere from 750 to 850 and those motors are running constantly at 8 to 9000 rpm producing 8 to 900 hp. Trust me, get a holley 650, maybe even a 600. I wasted $500 on an oversized carb and wasn't happy. To give you an idea: my car is running 227cc intake ports, Lift .468''/.489 '' Duration 262°/268°, with a 600 carb, and it is an absolutley an outstanding setup for it. Granted you have a more displacement than I do, but technically my car should probaly run a 570. I know where your coming from, all of us on here do, when I first got my LG4 I was stupid and put a 700 on, it sucks when your in 4th and stomp it and that motor says BBBBBOOGGGGGGGG. Good Luck

my statement stands.. not enough cam for a 700.. stick to the 650dp

Hey guys, thanks for the posts I will go with the 650, I'm not a carb guy so tuning it will be guess work but that's how we learn.
thanks agian

Don't stress, I bought a new Holley about 4 months ago. They pre-set the floats from the factory to get you really close, the main thing you will have to worry about is adjusting your idle. Thats only one screw...pm me if you need help, good luck with her!

I know I'm extremely indecisive but the more I thought about buying a carb the more I would like a VS, I won't be at the strip much so it makes sense to me. My latest question is; would I be ok with a speed demon 750 vac? They used it for my exact setup in the danger mouse superchevy write up. Speed demon does have a crate 385hp 750vs that would be close to what I have. maybe