Multiple problems

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85GTdude

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About 5,000 miles ago I rebuild my '85 GT and had it bored 30 over. Ever since, I've been having multiple problems with it. My brother and I have tried to work out the bugs with it but it only seemed to make things worse (never changed the gaskets, which is probably some of the problem). The parts that we have taken off were the Intake Plenum and the Throttle Body. Here are the problems that I have been having with it,
- Exhaust leak
(I don't know if this is because of a clog or if the gasket is bad where the leak is occurring. This exhaust piping has never been separated since the rebuild)
- High Idle
(This is one of the problems I believe is being caused by the gaskets)
- Backfire
(This could be caused by timing issues, I've used a timing light, but to little success)
- Burning too rich
(This is another of the problems that could be caused by the gaskets)
- Rough shift
(This occurred when I adjusted the distributor cap, after using the timing light. This actually caused the engine to idle lower by a couple hundred RPM's)
- No power
(I've had multiple issues with this. If I retard the timing enough it'll idle around 3k and have plenty of power, but it'll fowl plugs over time)
- Fowling plugs
(This could be linked to a few of the problems that i have listed above)

Any help would be greatly appreciated, Almost everything in the engine bay has been replaced, short of the vacuum lines, cruise control, and a couple other vacuum related components. And as I said, this motor only has 5,000 miles on the rebuild and I have way too much money in this car to just give up on it.
 
Still trying to figure this out... I would like confirmation or correction on my assumptions and any other probable causes for the symptoms I'm having. This is my only mode of transportation other than walking and I don't want to run it because the gas tank runs dry fast and I don't want to cause any more problems. Any help would be greatly appreciated.
 
Id start by replacing gaskets. As for the timing light.. take it to a professional to be sure its done properly. Running rich could be gaskets leaking. I'm not 100% but that's where I would start.
 
As soon as I get the money together again I'll get gaskets. Hopefully that fixes the problems I suspect they've caused.
The timing was 'fixed' by my grandfather (who has EXTENSIVE experience working on cars). I'm assuming that there's a possibility that my cam is offset.
Any ideas on the other problems?
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-The high idle could be an intake gasket leak causing it to pull in extra air.
-as for fouling plugs it could be its running lean from the leaks and dumping more gas into the engine than it can burn off.
-for the rough shift... I'm at a loss.

Note: I am not a professional mechanic but I've been around cars and trucks, race cars of all kinds, and other performance vechiles since I could turn a bolt out. I will do some research and try to find more info for you. But I would definitly start with replacing all gaskets.
 
-The high idle could be an intake gasket leak causing it to pull in extra air.
-as for fouling plugs it could be its running lean from the leaks and dumping more gas into the engine than it can burn off.
-for the rough shift... I'm at a loss.

Note: I am not a professional mechanic but I've been around cars and trucks, race cars of all kinds, and other performance vechiles since I could turn a bolt out. I will do some research and try to find more info for you. But I would definitly start with replacing all gaskets.
 
Thanks for the help and dedication to my problem. I'll be getting the gaskets a little later and will be replacing them soon. When I get them on I'll return with either good news or bad.
 
Check/replace the vacuum lines.
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Not changing the gaskets is a big problem. Also there is a tube that comes from the lower intake and plugs into the rear bottom side of the throttle body for the IAC. If you did not put a little oil on the O-ring, It may have twisted and cause a major leak as well.

Did you mess with or change the timing chain? If so it sounds like you could be 1 tooth off. Hook a vacuum gauge up and see if it is pulling even vacuum or if the needle is bouncing like crazy. Even with a vacuum leak the needle should be a faily steady just low. If it is bouncing all over the place the cam is not set correctly to the crank meaning the timing chain is off.
 
Thank you for that information. I haven't done anything with the timing chain, but I suspect that it may have slipped. I'll be replacing the gaskets and running tests tomorrow after an interview. I'll know more then.
 
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