The Eddy Magnum heads are advertised at 58cc combustion chambers, but they are more like 62 to 63cc, I had to have mine shaved .030 to get to 58cc
Out of the box the valve stem clearance is too tight and must be checked.
Aluminum heads allow you to run higher compression as a lot of the heat is...
Thanks....Tons of hours, I've done everything but build the short block, head porting, Tig welding the moly cage and the CRT 727, and...my Thumpercarb modded 950...Icing on the cake.