I was rebuilding an old .40 (#8011-small front bearing) today with parts I aquired through E-bay. The original engine is from somewhere around 1981 or '82 and it has a crankshaft with a non-circular counterweight, while the cylinder head has a hemispherical dome that is smaller than the cylinder bore. This results in a shoulder machined into the head.
Replacement parts I received were very different-the crank counter weight was circular with a thin metal band around its circumference, and the cylinder head was hemispherical, but the diameter of the sphere was much larger than the original, and it extended to the cylinder bore which eliminated the machined shoulder. I imagine these were changes made through the course of production. I would be interested to know if anyone knows the timeline, and or reason for these changes. Also, are any of these parts desirable or not? Thanks Greg