Muffler Tail Pipe Clamp

 

Have you ever wondered why the exhaust manifold on a Model A becomes distorted and leaks after years of operation—why the outlet of the manifold is no longer vertical? That condition is not normal; manifolds were not always that way.

There is a reason for this and it is not just because of continuous heating and cooling. Many people installing the muffler will tighten the clamp bolt where it fastens the muffler/tail pipe to the frame, obviously to keep it from rattling.

This bolt is only supposed to be little more than hand tight. That is the reason for the castellated nut and cotter pin—so that the bolt will not become un-screwed and fall off. The reason for this is to allow the tail pipe to slide forward and backward when the exhaust system is heated and cooled alternatively. If the clamp is over-tightened the exhaust manifold actually bends when the muffler expands.

I found multiple videos on installing new mufflers, and none mention this, but yes, cast iron will ‘bend’ under these conditions. So remember, do not over-tighten your muffler/tail pipe clamp.

Source: Tiny Tips For Your Model A​

Illustrations from Aries Muffler & Eckler’s