zraffz

I am converting my old 1994 Z28 from fuel injection to carbureted. This car is just plagued with electrical issues from the previous owner's hack job on the harness and I just don't feel like wasting any more time chasing wires.

It's a 355 that sees upwards of 6,300 RPM at WOT (ported LT1 heads 2.02"/1.6" valves, ported dual plane intake, CC503 (224/230 cam). Makes right around 390-400 crank horse.

I have always been biased to Holley and feel like I am over complicating my decision. My gut is telling me to just go ahead and pull the trigger on a 670 Street Avenger and a few friends are trying to push for the 4160 style 750 or 770 SA.


Am I right with my choice of the 670 or should I step up to a 750 or 770?

FRMULA88

http://www.holley.com/applications/C...bSelection.asp

650-770 CFM is what I come up with.


It is important to remember that smaller CFM carburetors will provide better low-end throttle response while higher CFM carburetors will deliver high rpm power

The bigger carb makes perfect sense on a track only car that is going to see 6300 RPM on a consistent basis. HOWEVER you may like the slightly smaller carb for a street car.

A bigger carb can be fine tuned if you get one with air bleeds and the 100CFM is hardly going to make a difference here..

sofakingdom

iTrader: (1)

750ish is about right for max power. 650ish for the street.

Don't mess around with some weenie 4160 regardless. Get one that's somewhat tuneable.

zraffz

So we are all on the right track... with this being mainly a street car with the exception of a few visits to test & tune a year; I should just stay with the 670?

I've never built strictly a drag car, I heard 770cfm and instantly thought it was overkill but I guess it really isn't.

FRMULA88

Stay with a 4150 style carb

I have a 950 CFM QFT Q series. It will start right up and idle all day, LOL my right foot is the "choke" on cooler days until it warms up.

BUT it is properly tuned and more importantly the right size for the intended application. 421 CU IN with a 6800-7200 RPM peak power band.

Not a daily driver by any means but I have put some street miles going to car shows.


You may be happier with the slightly smaller carb on a 80% street 20% strip car, if it was the other way around I would opt for the larger carb..