Originally posted by Jimwill52:
Just a guess, but since so many things were in short supply during the war it may have been difficult to get coolant... thus the need for a little extra engineering.
I could be wrong!
Don't forget that WWII was during the transition from alcohol to ethylene glycol as antifreeze. I don't know what was available during that time frame, but I would bet that both were in short supply.
Also, the 261 (and the big cube small blocks) have steam passages from the block to the heads which are not there in the 235/216 engines.
