Hey all, Almost done with my 4bbl swap on my 72. i attempted to put a Holley replacement carb on here that someone had given me - but it’s a pain. It had a stripped screw. Leaks everywhere. It’s done nothing other than make a mess all over my freshly painted Intake. I don’t want to bother with this carb. So, time for a q-jet. I’ve read through some posts, and looked at quadrajet power. Other than turnaround time, I’m sure he has my carb on a shelf. I would like to rebuild one myself, but I am a little confused. I know not all q-jets are the same. But if I got a 750cfm chevy- would all I have to do it change the jets and metering rods? This is a stock setup - aside from the 4speed I put in. I already added a wire for an electric choke. I also made a fuel line for this Holley - so a Chevy q-jet would hook right up. What else do I need to consider when looking for a core? also, if anyone has any spare q-jets lying around, let me know! My car has been on blocks for nearly 2 months - I’d love to drive it again!! thanks for the advice!
You might look for a Pontiac or Olds Q-Jet instead, since the Chevy inlet is on the driver's side instead of in the front. An unmolested carburetor from the "same size" engine will probably be a close match, in terms of calibration. You'd have to compare linkage and so forth, and whether you have an automatic (350 and 400 are also different). It looks like member @Sebambam has some carbs for sale.
so, I already have a fuel line that I made for this Holley. Are there any internal differences between a Chevy and Buick?
I would not use a chevy carb, personally. They generally have huge air bleeds and dont like to run right on buick engines without lots of fiddling. Best bet is find the right qjet for your engine and re build it well. #7042244 If you are going to tackle it yourself there is a book I recommend.
I agree. BUT, not to put too fine a point on it, how would a Chevrolet engine's carburetor of equivalent engine displacement differ in the ways you describe from a BOP carburetor, in terms of calibration?
Totally different air passages, rods and jets. Unless building a custom modified carb it’s best to use a Buick 350 calibrated carb.
Yup, @Cliff R has gone over this topic on here. These carbs differed in more ways than just jets & metering rods. Go to his profile & read through his posts.
And that is the reason why Q-jets are maligned as frequently as they are. Each Quadrajet was calibrated for the year engine line it was intended for. They are not all the same, and it is more than jets and rods. You can't just throw any Quadrajet on any engine and expect it to run right. You can do that with most out of the box Holleys, but not with Q-jets.
I’ve been told to stay away from ‘75 carbs. Are they really that bad? Or are they just not as favorable?
The ones with the single APT rod/jet you should avoid. 76/77 and later BOP with APT access thru airhorn are good cores to start with. Get a copy of Cliff R's book and you will learn many things about these.
