Interesting observation/comment Fred.... the 216 did not have steam holes from block to head....

For some reason they seemed to trap heat/steam in the upper recesses of the head..... and of course steam is not a good coolant as liquid water is...

According to the GM 1942 military shop manuals the military was privileged with the early ethelene glycol antifreeze similar to today's brew but no doubt not as exotic. They relied on single weight oil for the crankcase and added gasoline or kerosene to the crtankaces before shutting down the engine to dilute the viscosity.
On start up you were instructed to fast idle for 30 minutes to boil off the dilution liquids(gas or kerosene) before getting under way and/or pulling heavy loads. Dilution rate of 8 ounces at 0F and 16 ounces at -40F....

...and trucks had no heaters....initially... then they got wise and retro fitted a lot of them...

By the way the line venting to the Rad tank varied from 1/8 copper to 3/8 rubber hose.... some with a 1/4 turn valve and others without.

If I can find all the right brass fittings, I may plumb my 261 to look more like the old 216....

Any other suggestions or pratical experience with that contraption?????

Bob C.

Bob C.
CMP Heaven
The Hammond Barn