I doubt it’s piston slap! My piston to cylinder clearance is .0015” on the dot!! And thank you!!!Just got back from our excursion and played your video. Nice setup and Sweet fleet! Especially the small cart and cycle, I bet someone's mighty happy with those.
Something else crossed my mind, piston slap. Has a different sound than bearings or lifters though. Hopefully just something loose in the pump. Maybe in your advance mechanism, there is a field that you can view it from on vcds. I suppose you could see if it is bouncing around maybe. Or if you have a friend who gets brave after a couple beers, stick him under the hood to find where it's coming from
A side note, though I know it's to late. The Molinar rods Frank carries are from a fellow who was introduced to rod technology back in the '80's when we worked together at Oliver when they were getting into main caps and rods for stock cars.