im putting a 4 1/8 crank in a 41 merc/truck block for a 3/8 by 3/8 motor. ive only done this before with a 59ab, and know you dont have to relieve the block or do anything crazy to get it to fit. never dealt with the prewar blocks with this. i dont think it has to be relieved, but would like some ***urance.
Should go right in. I have heard folklorically that an occasional 59 or 99 needs some minimal relief with late merc crank, but I've never seen this.
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