Allis WC engine

I recently bought a 1937 allis wc, it has the distillate carb and auxiliary gas tank, so I wanted to check the engine number to see if it was truly a distillate engine, and it started with a "W" like it should, but instead of ending with a "K" or "G" like the book says, it ends with a "HA" and I read on a different forum that it means it was tuned for High-Altitude, and I just wanted to check if this was true, and if there was still a way of proving its a factory distillate engine. Any knowledge on it would be greatly appreciated, Thank you.

I was seeing that myself, any ideas on the best way to do that? I've seen and been told not to trust a compression test of hand cranking, my thought was hook the belt pully up to another tractor.

Since 1937, the engine has surely been overhauled. The great majority of owners 10 or 20 years later saw the advantages of gasoline fuel and when an engine OH took place, got higher compression pistons. Without looking at my service manual, I'd say gasoline pistons would be 110 psi compression and kerosene 80 psi. Check with throttle in the wide open position.

Edited by DrAllis - 10 hours 15 minutes ago at 6:27am