If the vent holes were not necessary on the 261 head, why did GM choose to go to the effort to drill them in the first place? I love it when self-appointed experts try to explain why they're smarter than the engineers who designed these engines. Small block 400 V8's have the same type of holes drilled in the heads for the same reason- - - -to allow coolant to flow past the siamesed cylinders and prevent hot spots from forming due to low/no coolant circulation. The quickest way to create a boil-over problem on a 400 is to run a set of 350 heads without drilling them.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!