In like a 650CFM to 750CFM range,
what is the best model/brand for a carb?
I have an edlebrock 600CFM, however.. on a 350SBC how much flow is like the over kill mark with a dual plane manifold, and no super/turbo?

I was thinking either a
Demon
or a
Quick Fuel.

Demon:
Mighty Demon, 650 cfm, Square Bore, 4-Barrel, Dual Inlet (MECHANICAL SECONDARY), Silver, Each

Quick Fuel:
650 cfm, 4-Barrel, Down-Leg, Billet Metering Blocks, Dichromate, Dual Inlet, MECHANICAL SECONDARY

Thanks guys,
-Louis

600 to 650 cfm is all you need for a stock or slightly modified engine. Much over that and you can have some stumbling problems on low end. The Q-Jet is rated at 750 to 795 cfm but due to its spread bore design it only flows as much as needed at low speeds and the large secondaries open up when necessary.

I don't have any experience with Demon or Quick Fuel carbs, but a local speed shop swears by Demon carbs. If you're running a stock or near stock cam, you might want to stick with vacuum secondaries as they're simpler to deal with. With a bigger cam, you'll have low vacuum anyway so go with the mechanical secondaries.

For a street car a dual plane intake is what you need. It will have better low end and better idle. A single plane is better for higer rpm needs but low end will suffer somewhat.

GM put the Q-Jet on those things for a good reason. In my opinion it is the best street carb.... period. On the L48 it is rated at 750 CFM.

If you plan to race a lot or seriously modify your engine, which you gotta do to the '77 L48, go with a Demon, but for mostly street use the Q-Jet can't be beat. It noticeably outperforms a 600 CFM Holley or Edelbrock in my ZZ4 powered '78. Don't waste your dough on anything else.... Q-Jets rock and they are getting increasingly hard to find.

The q-jet has smaller primaries and larger secondaries than the others.   A carb works best at 1/2 to wide open.  It's more efficient then when closed further.

Due to the smaller primaries, they are open further for the same power application.  This makes the carb and engine more responsive at part throttle openings, and creates better fuel mileage.  At wide open you still have total volume available.  It is the best street carb out there.

Now for straight up performance the Holly is better.  Why?  The bores are equal spaced, and therfore deliver fuel more evenly to all cylinders under hard engine operation.  They win on the track.

Now what do you want to do with the car?  Choose your carb.

Ken,

Very eloquent presentation!! I had mine remanufactured by Jim McGowan at "The Quad Shop" in Rockford, Ill. It is as responsive as a tuned port now, but not cheap at $345.00..........

Dave