Hi Joe,
Wrist pin size is different, pin location is different, as is the piston O.D.
Vintage wrist pin is 9/16"[.5625"], whereas new pin is 14MM [ .5511"]
Vintage bore is 2.25", new bore is 57 MM [.2244"]
Pin location is .040" higher in new piston [piston doesn't reach top of cylinder].
Most often the rod bushing is changed to fit the smaller wrist pin, however I just use a reamer to open the 14 MM hole to 9/16" and use the vintage wrist pin.
The difference in the bore is resolved by boring cylinder to fit new piston.
Wrist pin location is harder to correct, a thinner base gasket and new style copper head gasket will help restore compression level as current replacement head gaskets are thinner.
Most of the time I mill .040" from bottom of cylinder to compensate for wrist pin location.
Have fun,
Wrist pin size is different, pin location is different, as is the piston O.D.
Vintage wrist pin is 9/16"[.5625"], whereas new pin is 14MM [ .5511"]
Vintage bore is 2.25", new bore is 57 MM [.2244"]
Pin location is .040" higher in new piston [piston doesn't reach top of cylinder].
Most often the rod bushing is changed to fit the smaller wrist pin, however I just use a reamer to open the 14 MM hole to 9/16" and use the vintage wrist pin.
The difference in the bore is resolved by boring cylinder to fit new piston.
Wrist pin location is harder to correct, a thinner base gasket and new style copper head gasket will help restore compression level as current replacement head gaskets are thinner.
Most of the time I mill .040" from bottom of cylinder to compensate for wrist pin location.
Have fun,