Thread: Quadrajet jets change

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Originally Posted by 65ny

Take a look at this link:
http://www.4wheelnoffroad.com/qjet.html

There is a lot of good info there. I am inclined to think that maybe your jets aren't your problem if the carb hasn't been modified already. Qjets are pretty forgiving if they are in good shape. I rebuilt a qjet recently using only the instructions provided with the kit and it worked great. Make sure your float is set correctly.

Thanks guys, I very much appreciate the info. I have heard very good things about Jet performance. I would be surprised if there were any of the settings off standard. When I got the carb, it looked better than new, and runs quite well. I will however check the float height while I am in there.

The reason I believe it is running rich is that the plugs are blackened, there is some black smoke, especially on hard acceleration, and the oil smells like gas (not good for lubrication). I did adjust the idle mixture screws to stumble, then 1/4 turn back out BTW. This carb is their stage 2 carb which they tell me has larger jets (they did not know which exactly, but probably #72's) for large engines, and mine is right on the edge of stage 1 and 2 (I am probably putting out in the high 300's at the flywheel).

On a side note, it does have flooding problems at VERY steep angles. Again, I know this is float related, so I will check that out.

Go to this forum and post your question, there are a few guys that know quite abit about Q-jets and jeting them and working with the rods.

---> http://www.chevelles.com/forums

Pat

I ended up figuring it out for myself. There were a few small difficulties getting those long thin rods back in for re-assembly, but I got it.

This is a 350 bored .030 over with Holley aluminum heads on it, which has a Jet performance stage 2 quadrajet on it. The jets in it were 77's which I think were too large. I switched to 70's. Now I have some bogging when I give full gas, and some flat spotting.

I think I will go to 73's or 74's to see how it does then. Surprisingly, 77's were rich, but not crazy rich, it still ran quite well despite too much fuel.