Quick engine overhaul question

SW EM · Jun 13, 2014

Should piston pins be able to turn in the pistons as well as in the rod bushings? I"m assembling my new 400 Tisco kit and only one piston had the pin go in solid and not turn when the rod was moved. Is this normal?

Owen Aaland · Jun 13, 2014

At room temperature the pin clearance should be .0001 - .0002 inches. At that clearance the pin should slowly slide through the rod bushing when held vertical and lubed with 30 weight oil. With aluminum pistons the pin clearance will become an interference fit as the temperature drops.

SW EM · Jun 13, 2014

Yes I had the piston pins fitted to the
bushings. My question is whether or not
the pin should be able to turn in the
piston head.

Owen Aaland · Jun 13, 2014

It depends upon the temperature of the piston. At operating temperature the pin will be free even though it is a light press fit at room temperature. It is not unusual to take some effort to remove the pins from the pistons when they are new.

SW EM · Jun 13, 2014

Ok, thank you. Also the side of the rod
with the number stamped into it faces the
camshaft, right? It would also be the.side
of the rod that is longer than the other.

Quick engine overhaul question

SW EM

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Owen Aaland

Well-known Member

SW EM

Member

Owen Aaland

Well-known Member

SW EM

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