516 vs 915

[triple black]

Any big differences in the 516 head vs the 915 head?  Both are closed chamber, right?  I'm thinking about heads for a 400.

[Chryco Psycho]

Yes & no , the 516 had small valves & a slightly poorer intake port , but you can install larger valves & hard seats [for the exhaust side ] & with some port work the 516 are a great head

[firefighter3931]

The 516 would be my last choice to use on a b or rb engine unless the only purpose was to bump up compression on a smogger motor. The small exhaust valves and poor flowing intake ports will hurt hp #'s unless they're extensively re-worked. The 915 is basicly a closed chamber 906 head and with much less work will perform very well. It depends what you're looking for out of the motor.

Ron