Exhaust Downpipe Clearance

[aj81spider]

The original exhaust manifold on my car was cracked so when rebuilding the engine I replaced it. I also have new motor mounts. The combination has created a situation where the downpipe (4-2-1 exhaust - the "2" pipe) is almost hitting my cross member. Almost means about 1/16" clearance. When I brake hard, or turn left the pipe hits and makes an annoying sound.

I took it to a muffler shop today to see if they could move it back a little. They didn't want to touch it and suggested I cut away some of the cross member to create some clearance. (I also noticed some oil dripping off the bell housing so the visit was a complete downer!).

Any thoughts on how to address this? I tried wrapping the pipe in muffler wrap at the intersection, but that only made the noise much more frequent and somewhat louder.

Thanks in advance for any help.

[76was124]

Do you have the old parts to see which caused a dimension change?

Cutting the cross member doesn't sound like a good idea to me.

[DanD]

I can't remember what year it started, but the later crossmembers are all notched there. I notched the one in my 68 many years ago to accommodate an 1800 engine and downpipe.

You can dimple the downpipe, as long as the dimple is gradual and not too deep.

[donm]

AJ, take it to another muffler shop. I had the exact same problem when I switched to a 4-2-1 down pipe. I took it to Bay State Muffler in Peabody, MA and they applied heat and were able to push it back enough to give the needed clearance.

[aj81spider]

Thanks Don,

I'll try that (once the Spider is running again!). Worst case I'll take it out to Peaboby - it's a little bit of a drive, but at least I know it can be fixed there.

[kgfiske]

I had the exact same problem in my 78 with a 73-74 style 4:2:1 exhaust twin down pipe. I took a 36" pry bar that has a tapered flatted end on one end and wedged it between the pipe and the cross member. I then drove it down further with a 2 lb hammer which effectively dimpled the exhaust pipe just enough to give it a roughly 1/4" clearance from the crossmember. No issues since.

[Exit98]

A.J.

I had the same issue on my 76. It was some time ago but as I recall I took my Dremel with a cutting wheel and just cut out a little oval on the crossmember to give me a little more clearance. Took just a couple minutes and I haven't looked at it since.

I have no concern that it somehow weakened the crossmember.

Dimpling the pipe is a good idea too. Never would have thought of that one.

[aj81spider]

Thanks both - It did look like a little grinding on the member would create some space, but it made me nervous. Knowing someone else has done it makes it more palatable. Dimpling the pipe is worth trying too.

Looks like some garage work this weekend!