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CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
As of recently ive been restoring an '84 Trans Am and have recently replaced the quadra-jet with a reman'd quadra-jet 'UREMCO Remanufactured Carburetors 3-3699', but after looking through the forums about the differences between the stock LG4's and L69's which my car comes equipped with, I was wondering if the original carb in theory could be a better performer then the reman'd carb I bought if properly rebuilt.
Still new to restoring, any and all help would be appreciated.
I'm betting the only difference is that one was originally on a manual trans car and the other an automatic. Are the vacuum ports the same? Other than that, the jets are probably the same and it probably is functional indifferent.
Quadrajets really don't differ in their body.... It's the internals and how well they are matched to the car... Primary rods, secondary rods, secondary hanger, accelerator pump. Any body can be made to be a great performer ( mostly) if you set up right.... So just buying a quadrajet that has been remanufactured means nothing. For some, changing rods or hangers can really change the car.... Remember that these are also computer controlled, so some of that ultimately comes from the programming.
Quadrajets are very versatile... Some people blame the carb.... But it's the setup .. I actually have a side business Roc'in Carbs that sells parts to people working on quadrajets.... My mostly improving their performance.
Sorry if this doesn't help, but it's not as simple as "buying a better one".... It's all in the setup. If you want to maximize the performance, you have to learn to tune both the carb....and the programming.
one was originally on a manual trans car and the other an automatic
^^^ This ^^^
Odd #s are for one, even for the other. My CRS syndrome keeps me from recalling which is which.
That said, if you'd ever stepped into an auto parts remanufacturing plant, you'd know how meaningless those #s are on a "rebuilt" ANYTHING. They tear em down, all the [one thing]s go into one [bin barrel box basket bucket whatever] to then be sent through their [stripping cleaning sanding polishing straightening screw-hole-tapping whatever] process(es), all of another [thing]s go into their whatever to get whatevered, and so on; then at the end they grab one from bin A, 2 from basket B, 1 off of pallet C, and so on, and slap em together. To some limited extent, they sometimes have records of identifiable parts (jets & rods for example, which have their numbers stamped on them, and can thus be more readily matched back up to the finished assembly) butt if they can't find a pair of whatever size or the right whatever, they'll just use whatever CAN find that's the closest. Keeping in mind of course, that the condition that THE CORES come to them in, kinda limits the condition they can GO BACK OUT in. Like, if some core came in with an ear broken off of the throttle plate, they can't rebuild that one; the fuel bowl (the thing with that # stamped on it) is now orphaned. Or, if that part # calls for 72 jets, butt they tore down a core with that # that they had for it and it had 1 76 and 1 71 in it and that's all that's in the basket, there's not alot they can do, if there aren't any 72s there. You might end up with 2 73s or some such, if you're lucky. If you're REALLY lucky, they'd adjust the rods they put in it, to roughly match the jets. Butt who knows.
This by the way, is why it's SO MUCH CHEEEEEEEPER to buy a "crate" motor for example, than to have "your" [short block, or heads, or yadda yadda yadda) "rebuilt" and returned to you intact. Costs come WWWWAAAAAAAAAYYY down by using mass production techniques. You can't mass-produce qty 1.
At this point, if you're happy with how it runs, best to just leave it alone. There's NO TELLING what you'd end up with if you took it back and asked for "the right" one. Don't poke the bear.
There are plenty of things you can do to a Q-Jet, computer-controlled or not, whether the motor is stock or not, to optimize it, for YOUR situation. In the end, it's all just fuel and air, and the castings only support that. So don't give up hope. Even if your carb isn't "original", there's probably some degree of possibility that it can be optimized further. Trust me, the # on the side of the carb is ONLY the beginning, if you're in it to win it.
