Okay, I've studied up on a bunch of carb info here on the board. I currently have the Edelbrock Performer intake on my 72 455. I made the mistake of buying a 750cfm for it. I want to upgrade to the newer 850cfm Edelbrock Performer Q-jet (part # 1910). Will it bolt up to my Edelbrock intake? Sorry for all the crazy questions. I'm new...HAHA. Thanks, guys. Shawn P. Boden
Is your intake a square or spread bore? Why do you think the 750 was a mistake? Same size as a '70 Qjet. The only problem you should have with a 750 is leanout at very high RPM.
I think that tuning what you have will get you further than just bolting on a larger carb that also isn't tuned for the car. Get some jets for the 750, buy some dyno time. Find a place with a chassis dyno and an exhaust sniffer. You can probably get it dialed in after just a few pulls. That will cost you less than another $400 carb. As an example, I put an 870 Holley on my car. Once we had the new engine on the dyno, it had to be fattened up three jet sizes on the primary side. Then to get the secondaries to open (vacuum) we had to remove a check ball and change the diaphragm spring. Only then was I getting the full benefit of the larger carb. I might have given away 10-20 hp running a 750 but, I was giving up that much and more with a big, un-tuned carb.
I also think that the Performer intake is drilled for both spread bore and square bore carbs, at least mine is. If you are set on changing carbs, one way to go is to have a Q-jet rebuilt and tweaked to your specs. There are a few guys on the board that do this. They will need to know the specs of your engine. Then they set the carb for your combo based on past experience. This avoids the dyno route and gets you closer to ideal than an out of the box carb.
