View Full Version : swapping q-jets

05-22-10, 05:58 PM
I'm looking to switch out my stock 90 q-jet with another thats off a mid 80s caprice. Just wondering if it will work. I dont think the new one is computer controlled. The old one is giving me too many problems and the one from the caprice looks to have a recent rebuild.

05-22-10, 09:21 PM
90 Brougham should still have the Oldsmobile 307 (the 350 isn't carburetted) and a Chevrolet carb won't work with Olds, because the fuel inlet connects on an angle on the Chevrolet engine.

05-22-10, 09:41 PM
I was thinking to modify the current line(cut it and run a hose to the side inlet). I found out its a 750cfm from an 86 caprice. Would the fuel inlet be the biggest issue?

Angry Matt
05-22-10, 10:02 PM
Yeah you can cut the line and use rubber fuel line, I've had it like that on my 472 for years without problems. It actually makes it easier to take the carb on and off to tune it.

I thought in '81 they all went to computers? Just look if it has the plugs for the air flow sensor and the tps, or post the numbers. I have a book that will tell you year make and model.

05-22-10, 10:56 PM
The cast number is 17086004. Let me know what other numbers you need, I got it right here in front of me.

05-23-10, 12:42 AM
Is THAT why my Carb has a rubber fuel line?:lol:

05-23-10, 08:12 AM
I think 17086004 = e4me. If that's true, then it is computer controlled and the only difference is how the fuel line hooks up. As Matt has said, rubber line works fine for getting around that.

You should have no problems with the swap.

Angry Matt
05-23-10, 01:43 PM
1708='80 and up, 6='86, 0=?, 0=chevy, and even #'s (4) = automatic trans, so it is the stock '86 chevy quadrajet. The only issues I've run into yet with swapping carbs for different years is the linkage. The cruise control chain and the throttle cable may be a little out of adjustment, or lack the proper studs. On my buick motor I just swapped the whole throttle body (or base plate) of the carbs so that I could keep the same linkage and it worked well.

05-23-10, 05:06 PM
Thanks for the help, I think I'm gonna try it when I get home.

05-23-10, 09:39 PM
So I put it in but I got a bunch of codes. The codes are TPS, MC solenoid and code 41(not sure what that one is, generic code book has 6 listings). It runs 10 times better on the gas but still has a bad idle. What gives?

05-24-10, 01:37 AM
So I reset the computer, ran it again and got a MAP sensor code.
It wont idle at all, way too low of RPM but I can hold a good idle with my foot a little on the gas.
The carb also backfires or floods when you floor it, not sure axactly what it does but I did hear a pop once when I floored it, the other times it just bogged down. I switched the base and that lined up all the linkages, the only thing different on the carb is the electric choke and theres no rear vacuum break assembly, hope thats right. Any ideas?

05-24-10, 07:32 AM
Well you may need to adjust the TPS, once that's dialed in that should take care of the TPS code.

Test your MC Solenoid to make sure it's functioning properly...most importantly check that the connection is good. On mine, the little snap was broken so I ziptied the connector to the solenoid and it still wouldn't make a good connection. Had to splice in a different MC connector.

Both of those things can ruin your idle, and the flooding when you floor it is almost certainly caused by the MC Solenoid (running at full rich if you have the code I think.) If it's not the MC solenoid then maybe your float is stuck? I dunno man, I hate playing with carbs.