Big Block Cylinder Heads "915 vs 906"

72ScampTramp said

But why 906's? If we are speaking in todays world 452s would be a better replacement. Non racing application. They already have the hardened seats. Flow wise there isnt much different. That mopar muscle article is really good and does well at breaking down each head.

Click to expand...

I should have 'explained' myself better.

It was the 'mind-set' in 1968, that if you 'swapped' on a set of
67' 440 'HiPo' Heads on a 68' 440, you would gain {20 to 25} Horsepower.

That was what Chrysler was 'promoting', with a gain in compression
of {+1.10}.

Bringing your 1968 '440' from 10.0 to 11.10 Compression-Ratio.