4x4 carbs

[dirty230]

Anyone have any experience with the holly avenger 4x4 carbs?

[JNSM653]

I currently have a 770 street avenger on my ZZ4 crate motor. Took some time to eliminate the off idle flat spot and it does ok. Still way to rich on bottom for me and what I do and need. I just ordered a SMI Quadrajet and will get it put on in a couple of months. Started with the first (don't remember the size) truck avenger they put out and it fell on its face while on freeway trying to pass, 3,500 rpm. Talked with holley and they sent me the 770 which works better at 3,000 up rpm but not as well idle to 3,000 rpm. I have 410 gears, 33" tires and an sm465 trany FWIW. I like the fact that the quadrajet has smaller primaries and larger secondaries to try to better match my needs (or so I think time will tell).

[Zoomad75]

Can't really bet a Q-jet for a carb on a truck. I've run mine from 4,800 ft altitude to 13,000 ft altitude playing in the mountains of Colorado. Never had to touch the carb on any runs. I've bumped timing up there, but the carb never stumbled. Nose up or down it just runs. Still it's not fuel injection. Don't start for crap when it's below freezing. Takes forever to warm up once you get it running when it is that cold.

The q-jet is no different than any other carb that it takes a little patience to get it dialed in. It just takes different items compared to the standard Holley carb to do the same thing. There are different versions of the q-jet that suited different applications. From a small block all the way to a 500 inch caddy engine, the q-jet has been used. Try to stick to one that was for a 350 and your jet and metering rod sizes should be pretty close if not right on. I'd suggest if you are serious on getting a q-jet to get this book:

Rochester Carburetors, Revised Edition: Doug Roe:...
It is probably the best reference on tuning and tweaking the q-jet. Well worth the money.

[dirty230]

Good stuff .