400 stroker cranks

I think the issue comes from the piston and counterweight hitting. At some point "big" gets too big. You can cut down the skirts, but the pin boss will still need to be there. Run the smallest pin diameter you can (custom rods), and the short skirt pistons (custom), and the crank with the counterweights as small as possible (custom machining, possible balance issues depending on the bobweights of the other custom stuff. Or - IMO the better approach - build a B wedge based KB block with available parts and get a stronger bottom end, and better cylinder walls, with shelf parts. ou can always tell them it's something else - as long as it makes enough steam to perform...lol.