In Reply to: Ford Model 9N - Engine Clacking posted by Bill Langenfeld on May 03, 2023 at 12:36:45:
Years ago I had a similar very noticeable clack noise on my 1951 8N. I was just positive that I had a bad rod bearing. With some friendly advice from a Ford tractor mechanic, I checked the exhaust manifold by the very rear of number 4 cylinder. With the tractor running, I put my hand about an inch from the manifold. I was getting leaked exhaust pressure from between the engine block and the manifold.
I removed the manifold and found that the gasket had disintegrated and metal was worn/burned away from both the manifold and the block.
Just a suggestion to check this before going too deep into a repair.