Piston ID

Piston ID

Thanks guys, got pretty close to 4.070 with my verniers, and approx 1.785" comp height, so with my redneck capabilities call it the 1.81.
So .030 over 340. You would think they would put something besides just the 265-99 on it, but what do I know lol.
Thanks for the lesson,
Cheers
Steve

qkcuda said
They look like the old 340 TRW 12.5 pistons I used to run back in the day. I believe you are measuring in the wrong spot. The ring lands are smaller than the skirt diameter, so they may be oversize

Rocket said
Compression height is the distance from the middle of the wrist pin to the top of the flat part of the piston.

340 stock compression height with a 3.31 stock crank is about 1.81”
360 stock compression height with its 3.58 stroke crank is about 1.67”.

Measure the flat part of the piston to the top of the wrist pin bore and add 1/2 of the wrist pin diameter or (0.984/2 = 0.492”) to the above measurement.

This should give you an indication which stoke crankshaft the piston is for.