I have had many small block chevys with 600 and 750 CFM carbs and the 750 never seemed to make a hill of beans difference. Now keep in mind these engines were no more than 350 flywheel HP. Recently I had beat the 600 drum on a 350 buildup. While I still feel that 600 CFM is enough to feed a small block 350 under 6000 RPM I did not anticipate the IMENSE DIFFERENCE in idle quality, engine sound and engine wrap up due to the larger primary butterflys supplying more instant on demand airflow. On my 425HP 350 I still think that the 750 CFM rating will never be fully used but I do believe that the small primaries of the 600 choke the engine until the secondaries open. DAMN WHAT A DIFFERENCE! I have not had a chance to drive the car yet but if it is anything as dramatic as the changes I have seen i'm sure I will not be dissapointed. I can not belive the sound difference, it's as if I just found another 50HP. So props to all those who use 750's on hot small blocks over 305 cid. From now on I believe that 750 on a 350+ HP engine is THE ONLY WAY TO GO!

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84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Recently Ported Heads, Installed Larger Race-Flo Valves and RPM Air Gap Intake (No new times)
Other Mods: You name it and I have probably changed it.

2001 Dodge Ram Quad Cab 5.9L 4*2

The Bowtie
ASE Certified Auto Tech
LIVE AND DIE BY THE ALMIGHTY BOWTIE!

 

welcome to the darkside

 

You know I've been wondering about that myself...I'll still be using the 650 DP I was on my 305, on my new hotter 350. Might just be worth upgrading....thanks Mike.

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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports

 

In the late 70's, I had a 302 (yes, a SBC 4" bore x 3" stroke) with 12.5 compression, the "original LT1" solid lifter cam, 2.02/1.60 angle plug heads, Torker intake, headers, and 600 DP (it was all the guy I got it from had to put on it at the time). With an aluminum powerglide w/stock convertor, it would fall on its face unless RPMs were above 2500.

I picked up a new 3310 (which they called a 780 cfm at the time), vacuum secondaries, and was told "That's way too big for your engine - it'll never work right." It started and idled just as good; but off-idle throttle response improved, I could stomp it from below 2500 RPMs without eating the steering wheel (mostly because of the VS vs DP), and gas mileage improved.

I never knew exactly how much power it made, but the 396 I've got now has just bettered the 1/8 mile time I got with the 302 the one time I took it to the track in 1978 (I had put it into a different '57 by that time): running the 302 with that 3310 with a stock 3-speed stick tranny (Hurst floor shifter), 3.55 open rear, next to no traction through 1st gear vs the 396 in my sig minus the Powertrax.

Yep, sounds too big to me...

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/'87 LB9 block, ZZ3 cam and intake, World 305 heads, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" Hedders, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere w/open diff & slipping tranny. Daily driver while Camaro was being put together.

 

No problem Jester!

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84 Camaro ZZ4 with HOT cam. 1.88 60' (12.98 @ 105MPH E.T.)
Recently Ported Heads, Installed Larger Race-Flo Valves and RPM Air Gap Intake (No new times)
Other Mods: You name it and I have probably changed it.

2001 Dodge Ram Quad Cab 5.9L 4*2

The Bowtie
ASE Certified Auto Tech
LIVE AND DIE BY THE ALMIGHTY BOWTIE!