[Jacques Reed]

Hi David,

Just remembered- if there are no recognized casting marks on the engine, the water jacket shape will give you a good approximation of the year of the engine. I assume you have the heads off if you have measured the bore.

I refer you to Vanpelt sales website.

If there are large triangular shaped holes between the centre cylinder bores it is a 1938 engine.
If the top opening is triangular and the bottom two holes are trapezoidal it is a 1939-42 engine.
If the top hole is triangular and the bottom two are large round holes it is a 1945-48 engine.

This should narrow it down for you. See attached photo of two different types of head gaskets showing the openings described.

Cheers,