Other GM engines that use positive rotators on the exhaust valves use a slightly shorter valve spring on the exhaust- - - - -about 1/8", IIRC, to compensate for the thickness of the rotator. Don't some of the 261's have a similar arrangement?
Jerry
I think all 261 used exhaust valve rotators, I have a 261 stashed that has them, as does the '59 261 in my 60 C10, 848 head.
