I'm installing a 3" exhaust system from TA performance into my '68 GS and am having some issues. I'm doing shorties with down pipes and the down pipes are angling up towards the undercarriage. When I put the head pipes on, they are not even close to parallel to the body. I don't see how they are going to engage the mufflers properly. Has anyone else experienced anything similar?
Dave, It's Tom. We have been talking (sent you photos of it hitting the crossmember) and although you've offered a couple of suggestions, which have been helpful, I thought I'd ask around. By the way, I got the gasket Monday. Thanks for the fast service on that! As we have discussed, I can't explain why I am having these problems. The down pipe on the left side hits the crossmember and angles up and the one on the right side clears the crossmember perfectly, but angles up. This means that the head pipes are angled to the point they hit the undercarriage at the other end. If I put mufflers on, I'll have to pull them down somehow to be in line with the tail pipes, stressing the whole system. We discussed the motor mounts, but I don't really think those are bad. Even if they were, I think raising the engine slightly (assuming that's what new mounts would do) would make the left side crossmember interference even worse. At the other end of things, if the transmission mount were lower, I guess that might help, but it's a new mount from TA. I even thought about putting my old one back in, but I must have pitched it because I can't find it. The only thing I can come up with is to use the flanges from the reducers as we discussed. I guess I'm going to have to use both of them now so I guess I need another gasket. My plan is to remove the reduction tubes (already done on one) and machine the flanges down so they are in the shape of a wedge. By doing this and using them as spacers between the headers and downpipes, I think I can change the angle of the down pipes as they come off the headers. Hopefully, this will be enough to correct, or at least improve, the angle of the pipe as it goes back to the muffler. Any and all thoughts welcome. Thanks.
None of this is making sense, I have not heard of all these problems before on your type of installation. I can't recall if it is possible to do or not, but see if the transmission crossmember is upside down, it is now sounding like the engine is not the correct angle, i.e. too high in the back.
The crossmember is stock and not upside down. It can only go in one way. You saw the pictures, hump up. The transmission is a Muncie M21 with your (TA) transmission mount. No shims underneath as were there with the TH-400. The crossmember is mounted to the frame with the original rubber isolators and brackets. I might mention this is a convertible. I know the xmember is different for convertibles, but I think only in length. Is it possible the motor mounts on the engine are on upside down? The engine has been out in the past, but I don't know if that is even possible to do. Even if the mounts were wrong, raising it there wouldn't correct the left side hitting the Xmember. I think you have to raise it there and still lower the back end. It's very frustrating as I tend to agree something is out of wack, but what...? I bought this system from TA based on reputation figuring they'd done it long enough and knew Buicks inside and out so it would just bolt in. But I'm at a loss.
Shouldn't the angle of the engine be an easy thing to check using an inclinometer?Think that's what it's called. I bought a cheap one to install my satellite dish. Somebody with the same engine should have an idea of the angle. I'd guess around 4 degrees or so.
I checked my motor mounts and they are correct. And the fan is pretty well centered in the shroud which makes me think the motor is where it is supposed to be. Maybe 1/2" off or so. I don't know. Maybe I'm making a mountain out of a mole hill. I'm about to go on vacation so when I get back, maybe I'll have a new perspective. I guess I should just attempt to put it together (beyond test fit) and see what happens. Just a little gun-shy about cutting the pipe to fit until I'm sure it's not a problem.
I heard drop top crossmembers had exhaust humps slighted relocated to one side. We ran into an interference with MT headers on a 70 GS 455 vert. Tom
