willysmjeeps.com

I'm just making a comment. and a question:
During my restoration I saved the old exhaust pipe and part of the tail pipe.
Yesterday I noticed that the diameter of the old pipes are 1-5/8" OD where as the new reproduction pipes are 1-1/2" OD.
I was going to make the vertical exhaust pipe. so I had the muffler shop bend me a section of 1-1/2" OD pipe. I had intended to use the triangle flanges from the old pipes untill I found out they were made for 1-5/8" OD pipe. I believe I can still make the flange work and fill in the flange space as I weld it.
I was curious as what actually is the correct Pipe OD for the M38?

The correct diameter is 1 5/8". The pipes that I am making are the correct size, not like the far east stuff everyone else sells.
John Bizal
www.midwestmil.com

Thanks John,
Well I wonder now, would the smaller pipe have any noticable effect on the engine performance?

I am not sure how much effect it will have, but anytime you start to add back pressure on the engine you get bad side effects. The better they breath, the better they run.
One additional item. Our pipes are also aluminized to help prevent rust. Not just painted.
John

What was the ID of your two pipes Ken?

The ID of the old pipe is 1-1/2. The ID of the new pipe is 1-3/8.