1966 L72

When removing my transmission to install a new clutch, I failed to separate the exhaust pipes from the manifolds. As a result the pipes now hang low toward the front of the car where they should be behind the shields. Everything went back together as I would have hoped, but when I was done, there were the sagging side pipes. I'm thinking of just getting the car to full operating temperature and placing a board under the sagging part of the pipe and slowly jacking under them, I think they will probably return to shape. I also thought of taking it to an exhaust shop, but I figure they will heat different areas and try to press them up the same way. Any thoughts? Thanks.

Vet65te

Larry - Not sure I'm following you completely. If the side pipes were still attached when pulling the trans, do you mean you dropped the back end of the engine and the pipes but bent because of that?
And is there a new 'bow' in the side pipes or did they just crimp in one place?
Mike T - Prescott AZ

1966 L72

Yes, that is correct, when I lowered the back of the engine to accommodate the removal of the transmission the pipes must have bent, however I can not tell where they bent. There are no creases. I assume an existing bend (I can not tell which one) just gave way some more. FWIW, I ultimately did remove the pipes to get the back of the engine lower. I had no idea they were bent until I reinstalled them.

1966 L72

Mike, also I am going to participate on the L72 count string. It is on my list of things to do once I get my car off of the lift again.

randy ransome

I would loosen the three nuts where the side pipe bolts to the exhaust manifold and try to push the front of the side pipe up then tighten.

Vet65te

Larry - As soon as I saw your 'screen name', I began to wonder...did I already send an email/PM to Larry or have the 150+ emails I've sent out just confused my old brain. Glad to have you post up once you get back off the lift.
So, back to the situation at hand...I think I understand now that the pipes have been tweaked a bit but since it's not totally evident as to where they bowed/bent/twisted, it makes it difficult to figure out where to make the correction.
When I got my 65 NOM L78 three years ago, it had a nearly new set of side pipes made by Sweet Thunder. To me, and maybe only me, they were seriously noisy. Not a good sound at all.
I sold them to a friend in Michigan and 'Mike' actually still talks to me :-O. So, when I started looking around for a replacement set, I wound up going to Gardner Exhaust. They just arrived about a week ago.
I'm not yet ready to install the new bigblock into the 65 but will do so shortly. So, here's what I propose and not sure this will help enough but maybe worth a try.
Let me unwrap the new Gardner Side Pipes and lay them on the concrete. You do the same with your pipes and then maybe we can see how flat mine are and about where they rise up and compare them to your pipes that now seem to
have an extra bend or twist in them.
I'll do this tomorrow and get back to you with pics.
Mike T - Prescott AZ

Golfobsessed

I had to do this when installing mine, I purchased my side pipe set frome someone and when I bolted everything up tight I noticed the pipes hanging lower than that covers in front on both sides.

I loosened up the three manifold bolts leaving the rear mount tight... I put a rag and jack under the front bend area of the pipes that were hanging low, jacked up the pipes almost to the frame and tightened the manifold bolts again, when i released the jack both sides were perfect.

66427-450

I understand your situation, I’ve had similar situations through the years (pipes that need to be bent for proper fitment), I would recommend putting the car on a hoist, use a torch to heat up a section of the pipe about half way? between the exhaust manifold and the beginning of the straight / chamber section with a torch, and then jack up/bend the pipe back where it belongs, I would NOT do it cold, with a cold pipe, that would put undue stress on exhaust manifolds etc. Just maintain adequate pipe-frame clearance (input as to where you heat/bend).

Kenny94945

FWIW The only idea so far I like in this thread is to first remove the pipes to find where the bend/ damage is.

Heat & jacking to fix/reverse a bend without knowing, well.....no.
Loosening exhaust bolts, jacking and retightening, well..... maybe.

Again, I'd chant "off with the pipes".
Good luck.

66427-450

Unfortunately there’s probably no visually identifiable “location“ as we’re talking about a relatively slight bend, you’d probably have to put it in a builders jig, or measure and compare it to a undamaged pipe. But yeah, that would be preferable, if you have access to a jig or pipe with “original” configuration to compare it to.

PS. I would imagine that when the engine was lowered and the pipes were stressed, certainly they rotated at the connecting locations at the manifold before they bent, so that would be the first thing obviously to check (I would assume that the OP had already tried that, as he stated that he had “bent” the sidepipes), to see if you could loosen, center, and retighten them.

DansYellow66

This is the first thing I would try. There’s a certain range of movement the bolted flange and pipe flare connection can take when tightening them up. I do always loosen them when pulling the transmission however.

napa68

This^^^^^^

1966 L72

I appreciate all of the input. As it turns out, I was wrong on the pipes being bent. This of course is good news. The advice to loosen, adjust, and retighten turns out to resolve my issue. It's nice to be a part of a group that has so much experience. Thanks everyone.