looks like some of the old guys i've talked to were right. one common problem to the 216's were cracked heads. my 248 has a crack not too far from a valve seat, but k-w block seal solved the problem. another common problems is rust closing off the holes in the block, causing hot spots that lead to the same result. i'm thinking every now and then using a good heavy duty flush ain't no bad idea. probably every year just to be safe. after 50 plus years of rusting, ain't no telling what goodies can break loose and trash an engine.
