I think we touched on the square bore thing earlier. He already has a Holley 650 spreadbore, so no adapter would be necessary.
Originally Posted By Region Warrior
Been mess'n with holleys and q-jets since the 70's. Holley's are easier. But when done right, q-jets out power and give better milage at least up 700 hp. Havent tried q-jets past that cause use 4500 dominators.
Well, I'd have to disagree on that. A Q-Jet will not out power a Holley. A Q-jet may provide equal performance under wide open throttle. Q-Jets are not designed as a wide open throttle carb, they were designed as a street carb. And they do that very well.
Quadrajets will run well on a high 12's or a 13-second car. Once you dip into the 12's, there are some shortcomings you have to address. Quadrajets have a tiny float bowl. You need a very good fuel system that will keep the volume up to overcome that small float bowl. Without a decent pump and some good sized fuel line, a Quadrajet will begin to starve on the top end. Beyond the 12's, you need a hefty fuel line (min 3/8"), and an electric pump, preferably bypassing the mechanical.
The GM engineers knew about Holley's superior performance, that's why they chose to use a Holley on their fastest cars. It really went against the grain to do that, considering companies like GM used Rochester Products exclusively after 1966. But the engineers knew they needed a Holley when they passed a certain point. Holleys were racing carburetors.
For those choosing between the two types of carbs, again, go with the carb that you know a little more about, stick with the one you already have, and rebuild it yourself. Both types of carbs will work well.
BTW, I don't own a carb rebuilding business, so I do not have a vested interest in convincing people to run one carb or another. You have to be careful about that, because on the web, people can give their opinion, then they get your business.
