Hi,

I picked up a used ZZ4 crate engine that is stock with the exception of the addition of 1.6 roller rockers and an Edelbrock Performer manifold. The previous owner told me he had a 750 Holley on it and that it was probably a little too big. He recommended I get a Street Avenger 670 cfm.

The car has a 3.25 posi, T-56 manual, and will be mostly street until I can get fuel injection on it.

I think he's right, but just wanted to see if anyone else had other suggestions/opinions. Thanks!

Ryan

Anything in the 650-750 range is about right. The optimum choice would depend on your gears, the car weight, how you use the car, the torwue converter, etc. etc. GM uses a 750 as their "ratings" method, so it can't be too far off. I'd be inclined to suspect that the PO either had this in a heavy car with a stock Turbo 400 converter or some such and a highway gear, or never really got it dialed in right.

http://www.barrygrant.com/demon/default.aspx?page=12

Demon has carbs calibrated just for the ZZ4.

I'm running a 650 Double pumper on mine, and its a match made in gearhead heaven. I tried a box stock 750 (80508) vac secondary, and it was too much carb for it. It killed throttle response, and was running too rich. It would have taken major tweaking to get it to work. I didn't bother tuning it, just put the DP right back on. Excellent response with the 650, and lets the engine pull HARD to redline. The 750 is too big for the ZZ4 IMO.

Originally posted by ZZ69chevelle:
I'm running a 650 Double pumper on mine, and its a match made in gearhead heaven. Excellent response with the 650, and lets the engine pull HARD to redline. The 750 is too big for the ZZ4 IMO. I have witnessed the same thing with a friends ZZ4.I loaned him my Holley 650DP (4777).

Lets just say that I never got that carb back :D