i built alot of 4.250 some4.500 and 4.375 cranks and 4.750 soon a 5.500 crank engines buttons are not going to help much if you have a stacked ring pack and the 2 ring needs to run thru pin center so at that point a shorter rod. i was telling the guy at oliver rod about the mccarthy rule it states the rod should be 2 inch longer then the stroke and your good :) i never seen a 400 blow up from short rods:HMMM::D