I'm building an Olds 330 for my girlfriend's Firebird and would like your opinion on carb size.

Car: Pontiac Firebird Formula 1975 - 4050 lbs (!)

Drivetrain: TH350 with 3000 stall speed, 8.5" 10-bolt with 3.90 limited slip

Engine: Olds 330, stock stroke, 4.000" bore, 340 cid
6.2" rods, forged pistons, forged crank, 9.5-10:1 compression
Cam probably around 220 duration (not bought yet)
#2 heads, pocket ported, 2.07/1.71 valves, HS roller rockers
Holley Street Dominator intake, 1-3/4" headers, 2.5" exhaust

Redline: 6000-6500 rpm, 90% street
Will receive a 100-150 shot of nitrous once in a while...

I'm looking at the Quick Fuel HR series (I've got a HR-VS-680 on my Cutlass which I really like).
I'm thinking vacuum secondaries - too small engine/heavy car for a mechanical, right?
For size I'm looking at their new 735 cfm, or should I go smaller?

What do you guys think?

https://www.quickfueltechnology.com/...eet/hr-series/

 

The 750 Street Demon would be perfect.

 

While you could probably run your engine with a 700+cfm carburetor you might be better off going with a 600 cfm carburetor. Check it out :

https://www.summitracing.com/experta...cfm-calculator

 

Thanks for the replies guys.

Those calculators might be a decent start but they're a little blunt IMO. Only redline and displacement isn't much info and what does street/race really mean (I go WOT to redline almost everytime I take my street car out - would that place me more in the race category?)?

Since almost everyone usually agrees you should go bigger than the calculators say something seems to be missing in real life situations. Or everyone is doing it wrong...

I'm thinking a carb in the 700-750 range would definitely be appropriate for peak power but would it hurt driveability/atomization down low? 4050 lbs of car and a small engine might say so but then again - high stall and gears maybe offsets the effect?

And how does intake design contribute - does the bigger open plenum on a single plane mandate a smaller carb or is that of no importance?

 

The Street Demon is heavily based off the Carter Thermoquad and has a 3 barrel design, body options including Aerospace polymer and triple stacked primary boosters, meaning great low speed operation. I would think it would be close out of box but a complete tuning kit is available.