The '85 GT I bought yesterday sounds like a ups/delivery truck. It is absolutely horrible. I'm going to jack up the car tomorrow and take a look but it looks like one side of the muffler has no pipe coming out of it and the other side is only 6 inches long. Thought it was completely missing until I got down on my knees and checked. The engine DOES need a complete overhaul when it comes to flushing out and replacing fluids, and an average tune up with new plugs, wires, cap, rotor. I know it is probably a mix of everything but is the main problem the exhaust? I'm getting ready to chop it off as far up as I can removing the whole system which would make it straight piped minus the pipe, right? Obviously I'll put a new system in it eventually.
[This message has been edited by huracan2015 (edited 11-16-2014).]
Check for loose or missing manifold bolts. So far I've found two that just plain weren't there. There is a big gap between the firewall manifold and the head. It's hard to get in there, to say the least. The bolts are M8 x 1.25 x up to 45mm. You may or may not be able to find them at a hardware store or Menards. I tried the TFS studs, but there wasn't enough clearance to turn the stud with a socket. It worked its way back out pretty quick too. It's pretty clear this is the cause of most of the noise in my 85 GT, which otherwise sounds great. Of course it does have the GT tips.
Yes, plus dual tips. It looks like someone has installed part of a Duke exhaust on your car.
Yup, aftermarket muffler and tip. I used to have a set of OEM tips for sale. If you are interested, I will see if I have them. You will need a different muffler. Also, I see it is resting on the e-brake cable... not good.
The missing bolt issue on the manifolds is a real bear of an issue.
They are likely broken and inside the head. You have to get a carbide bit and drill in and then use a bolt extractor to get them out, or drill them out close to the threads and re-tap. On my old heads I had 3 heli coils for this very reason.
You can't do the job with the engine in place. You can if you unhook the rear cradle bolts and drop the engine down. There are a few wires etc. to keep track of when you do this, but, it frees up some space on the front bank.
Believe me when I say that you can't get the engine to either run right or sound right with missing exhaust manifold bolts. And the fix is an unpleasant job, so good luck with it. And don't look for shortcuts. They don't work.
I'm just going to cut it out today and go open headers. I'm not driving it so don't worry, I know about loudness, tickets, etc...
Cut it out where exactly? If you just disconnect the Y-pipe it's going to be very loud and still run like crap. If you cut it off at the inlet to the muflfer, it should be able to run OK (assuming the cat isn't clogged), but still be very loud.
I'm going to cut off the muffler today and see what that does. Eventually I'll replace the whole system but I'm just doing this for now. I'll be using a small cut off wheel or maybe even a dremel depending on if I can fit it under the car, but I'm worried about cutting so close to the gas tank. As long as I don't cut the tank should I be worried?
[This message has been edited by huracan2015 (edited 11-19-2014).]
It was all rusty so I borrowed a small cutoff wheel from a friend. Took off the muffler, and also found out someone put a cat delete pipe on it (yay). So now it's basically straight piped. I need to still cut the downpipe off eventually and replace it with a larger diameter, but it's fine for now. I think. It spits flames when I rev it. Bad? Probably. Cool? Yes.