[73nova350]

What would b the best size carb to use for a sbc 350 with a comp cam kit duration 280 , 480 lift, and new valves and springs to match the cam, and a wienad team g manifold

[eloc431962]

Is that all that has been done to the engine no internal work / head work?
What heads are on it ?



Cole

[73nova350]

Stock heads 194 intake valves , msd street fire distributor, long tube headers, no internal work besides the cam, lifters and 1.5 roller rockers

[lg1969]

Were is it going in?
Is it an stick or Automatic?
What gear ratio you are running?
All this you have to consider.

[techinspector1]

Originally Posted by 73nova350

What would b the best size carb to use for a sbc 350 with a comp cam kit duration 280 , 480 lift, and new valves and springs to match the cam, and a wienad team g manifold

Not knowing all the details, I will say generally that I might use a 650 vacuum secondaries for a street cruiser, 750 vacuum secondaries for max power with a converter that stalls under 3000, 750 double pumper for max power with a manual trans or a converter that stalls at 3000/3000+.

[ap72]

Originally Posted by techinspector1

Not knowing all the details, I will say generally that I might use a 650 vacuum secondaries for a street cruiser, 750 vacuum secondaries for max power with a converter that stalls under 3000, 750 double pumper for max power with a manual trans or a converter that stalls at 3000/3000+.

I agree with this. If nothing else has been done then you could probably even use a 650 for max power as well, the stock heads, exhaust manifolds, and exhaust are going to choke back a lot of power.

[73nova350]

Automatic with a stock stall and stock posi rear (I believe 355 gears )

[73nova350]

Also has long tube headers cherry bomb vortex mufflers msd street fire HEI distributor

[lg1969]

You need a 600 vacuum secondary. The automatic and 355 gear, stock 9:1 compression, Using the 280H cam it's a Holley #1850 carb.

[73nova350]

Thanks for the advice , what is the benifit in this situation of vacuum secondaries instead of mechanical

[lg1969]

With vacuum secondary it will less of a chance of bogging when hit the gas pedal.
Mech. secondary carb will have Lean bogging because of the gears you are using and the cam you have. It's even worst you are using a stock converter. Gas mileage will suffer with DP carbs. They are for all out racing.
If you had a 4 speed tranny or a loose converter and 390, 410 gears, then 650DP will work very nice.

[techinspector1]

Originally Posted by 73nova350

Thanks for the advice , what is the benifit in this situation of vacuum secondaries instead of mechanical

The motor cannot use all the mixture from 4 venturis at low rpm. Having the manifold suddenly see that much daylight could reduce manifold vacuum to the point that there is insufficient differential of manifold vacuum/atmospheric pressure to fill the cylinders and the motor would simply die. Once the r's are up and the motor is gettin' up on the cam, the motor will abide the slightly reduced manifold vacuum which occurs when the secondaries are opened and the motor begins makin' max power a split second later. This is how I see it in my mind, I didn't read it anywhere.

[lg1969]

I agree what you wrote, tech.