Do all early hemi engine have two rocker shafts,
I though I read about single shaft hemi heads and
that TRUE hemi had two shafts per head.
Thanks

All early hemis (Chrysler, Dodge, and DeSoto) had two rocker shafts per head. Also all gen 2 and gen 3 hemis have two rocker shafts per head. The single shaft Poly is sometimes referred to as a semi-hemi because of the twisted orientation of the valves but it is neither a hemi or a wedge.

Thanks Centerline

Chrysler manuals at the time referenced single-shaft and double-shaft engines without reference to the combustion chamber design.

Perhaps I read this from a Chrysler manual

To add to what was said above, Chrysler Corp developed the Poly motors to save money as they only had one rocker shaft. I believe in general the intake manifolds swap in the same engine families. Crank and rods were the same, only pistons were changed.

IIRC there were a few Poly engine sizes that were not offered in Hemi style and some racers in the '60s would use a Poly block that was the right size for a class and put Hemi heads on it. As I read this in Science and Mechanics Magazine around 1966 I may not be remembering clearly.

Poly engines could be quickly identified by their valve covers that had scallops on the exhaust side.

R.

Dodge 325 poly to hemi...Same block is in all pictures.