Just picked up a 86 trans am, used to be tpi and some hack tried putting a carb on it. It was dark when I bought the car, and drove it home 100 miles or so.

It got terrible mileage . eight miles to the gallon and I was only going 50 or so

Constant backfiring through carb under any sort of load

went through 5 quarts of oil,

___what I found and fixed so far___

Found out the, back two bolts that mount the carb in intake were stripped, I fixed them.

The fuel pressure was 12 psi overloading the carb, installed a regulator and put to 5 psi.

The quadrajunk was still junk and leaking gas even after the fuel pressure issue was fixed, so I put a different quadrajet on finally stopping the leaks

Oil leak was fixed because the front fuel pump bolt at front of motor was left out

Timing was set at 0, i set it at 6btdc with vacuum advance unhooked.

---- issues i still have with it----


Car still backfires through carb when secondaries open up, although it is much better than before. It WILL not rev past 4000.

Idle/ timing is perfect at 6 degrees - 700 rpm as long as vaccuum advance is unhooked, as soon as I hook it up, the idle goes up to 1300. I cant back the idle adjustment screw off anymore.

There is NO ported vacuum on the carburator anyplace, believe me i've checked

Im unsure about the TV cable adjustment, and the bracket they used.

 

You probably need more ignition timing. 8-12 BTDC at idle w/o vacuum advance is pretty common.

Make sure your high idle cam is disengaging. And you don't have anything else hanging up the throttle blades (including gaskets).

 

The idle is fine and runs and sound great, but only with vacuum advance unhooked. Plug it in and it pulls it way advanced and then idle wont come down, even if I pull hard on the linkage. Its as low as it can go. Unfortunately I cannot find a ported or timed vacuum port anyplace on the quadrajet, believe me I've tried. The one that is up front on driver side that I read was supposed to be ported isn't.

So how much mileage would I lose, unhooking the vacuum advance? And to counteract it bumping up the base timing to maybe 10?

This is a low budget car, mostly since I don't have any money. I don't care if its fast or not as long as I can drive it daily.

 

Sounds like carb problems! Id get a better one if possible. Sounds like this guy that owned it just slopped it together. Check the simple stuff first! Pull a valve cover and check the valve lash. Overadjusted valves can cause spitting back through the carb

 

Im not sure the history, I think some kid tried making a hotrod by ditching the tpi and putting on the car
Everything that could be messed up and done wrong on it was. Then I think they ditched the car because of it.

The carb it came with was junk, I mean it actually leaked fuel out the side.

I found the one on it now, it works better but is still a Junkyard special.

 

This is just my opinion. But if I was you I'd save my money up and buy a nice Holley or edelbrock. There's problems that can be really aggravating but it's almost always something simple. Try things 1 at a time. If you do too much at once and the problem gets worse then your not sure what caused it.

 

This entire car so far has been fix one thing to find something else broke.

Im all for a holley carb. And intake swap.
But first I want to make sure this car is going to be worth it. At least be in good enough running condition that I wont feel so bad about it.

Then I want to eliminate the tv cable. I don't care how I do it, just needs to be gone. If I can do that and make sure this car is worth it then I will get a holley

 

Make sure the high idle cam is disengaging as 5.7 said... As long as that q jet is in good working order, don't be so fast to slap on an aftermarket carb. With a properly working qjet you can get your car to run just fine.

 

And why would you want to try eliminating the tv cable?

 

Because I don't want to worry about adjustments, geometry and brackets. Im dubious if everything on the tv cable is fine. I mean it seems adjusted at wide open throttle, and shifts firm at 2500 light load and around 4000 when you give it a little more. My biggest thing is that everything else on this was messed up so I am.sure that's not.right either I have no idea what the bracket is suppose to look like, and am hoping the tv cable didn't mess up the trans.

As far as fast idle cam, yep its off. The high idle seem more of vacuum advance timing issue than anything. How bad would it be to unhook vacuum advance? How much mileage will I lose?

 

What type of carb holley edelbrock or carter

 

If you run your car without the tv cable you WILL ruin your transmission, so please don't do this. Simple version: the cable controls shift points, tv boost pressure, and kickdown. The misconception that not having one is okay = you dropping $$ for a new transmission.

This is all under the assumption that you have the stock 700r4. What you might be getting confused with is the difference between a kickdown cable and a tv cable. A kickdown downshifts when you step on it, simply put. The tv is much different and absolutely necessary AND must be correct.

As for vacuum advance, don't unhook it. You will loose performance and gas mileage. You can figure it out, it's probably something simple. Is your vacuum advance canister adjustable? Are you sure you're not missing a vacuum port on the carburetor? Maybe one by the base that you looked over and left uncapped?