OD of New Pin         18 mm.                                Length of New Pin          53 mm.

OD of Original Pin    7/16"                                   Length of Original Pin    54 mm.   (but not always!)

 

[Don't forget that conrod little-end eyes are NOT central to their pistons/cylinder bores]

 

A suggested, possible way forward is to make up aluminium-alloy, or even bronze, bushes as per dimensions in the sketch.

Gudgeon_Bushes_.jpg

New piston circlips are of dia. 1 mm. wire: their tails would have to be clipped off. This is not a problem to their removal from a piston as handily, pistons have cast-in circlip access slots.

 

Tolerances:-   Between original 'pin and new bushes: "light hand fit".

                      Between new bushes and piston:  "medium hand fit/light push fit".

 

WARNING:- when fitting aluminium-alloy bushes to piston, ensure that surfaces are lubricated, not dry, to avoid possible cold-welding/galling.

 

Thermal Expansion Coefficients have been consulted: interference fits are not recommended.