I acquired an 84 Olds Custom Cruiser, originally to restore but has become my daily driver after some issues I'm trying to resolve with a rebuilt longblock....... Anyhow I took the carb off to fix the tps ajustment setup, someone did a terrible job with removing the cap over the adjustment screw. While rebuilding the carb the passenger side idle air screw broke of when trying to remove it, so now the left bank is rich:/ So my question is are the throttle base plates for these quads different depending on the engine it went on like the air horn and mid plate are? Just wanted to know as though I've tried I can't get the screw remains out and know I'd mess the seat up if I drilled it out. I will try to make a build thread, though it's gone a different route to daily driverdom. Thanks for any help, Nick
If you can find a rebuildable core of the exact same carburetor part number, you won't have any issues. GM engineers always designed each run of carbs to match how the engine was outfitted. Just make sure whichever throttle body you use, that the shafts are not worn--it would need rebushing which is difficult, therefore expensive.
I have access to a drill press, lathe and milling machine, I've already made some bushings for the primary and secondary throttle shafts, just didn't bother with it on this throttle body as I new I needed a new one! That being said, I was wondering if the throttle body's where different for each engine size. All I've been able to read and put together has been rather unclear, I know the air horn and midplate( can't remember what it's called, carbs are rather new to me, I've always had fuel injection vehicles) are tuned to the specific engine size with the different air bleeds and idle air tubes. Couldn't find any info on the throttle body other than the shafts often need to be rebushinged and the idle air screws and ports are gunked up. Thanks for your advice, if I tried to do the bushings without what I have at my disposal I would have been walking for a while I think Take care, Nick
All the later (75-90) throttle plates are the same with the exeption of the Q-jets made for the 252 Buick V-6's. They are not hard to bush as long as you remember to grind down the stake on the throttle plate mounting screws (bottom side) if you don't you will snap the heads off the small screws.
The throttle plates used on the 850 CFM q-jets are different. You can buy bushing kits from some of the places that still cater to q-jets.
All Q-jets after 1975 are 850 CFM models, exept for the 252 V-6 models. Happy to be proved wrong, but I have never seen a 750 cfm model after 1975.
Maybe this will answer some questions that seem to be conflicting with one another. http://www.carbkitsource.com/carbs/tech/Rochester/Quadrajet-index.html
