340 build

Them rod bearings are trashed!!!!
that harmonic balancer is for a Cast Crank, how about a close up of that Crank.
The marks on the piston, is where i had to grind to get proper valve to piston clearance.
I think it was over revved and floated the valves, causing the piston to valve interference.
on the counter weight of the harmonic balancer, get some scotch brite and sand the paint off. see if it says 340 cast crank only. or something like that.