Farmall 100 piston pin clearance question

belairbob · May 20, 2019

I am installing new pistons in my C123 engine. My machinist says the pins feel to tight in the pistons. The IT manual says .0002. He is concerned that with these new aluminum pistons with the steel pins that may be to tight. The pistons and pins came new together. Would appreciate your thoughts. Thanks, Bob

Janicholson · May 20, 2019

With engine oil on the assembly when pushed into place, hold the piston horizontal and move the rod up as far as it will go, touching the skirt
of the piston. let the rod lower with its own weight. If it gently moves lower by gravity, or requires very gentle finger pressure it is OK.
If it requires pushing down more about a half ounce it is too tight. if it drops like a stone with no resistance it is likely loose. The piston
is aluminum, and expands more than the much colder rod when in service. If loose when started, it will be hammering when warm. Jim

teddy52food · May 20, 2019

They should be fitted right from the factory. Just heat the piston & they will loosen up. Clearance is only 3 to 5 ten thousands.

belairbob · May 21, 2019

Thanks so much for your answers! I will proceed with the rebuild.

Farmall 100 piston pin clearance question

belairbob

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Janicholson

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teddy52food

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belairbob

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