07-17-2020, 09:09 AM
Amen to what Steve says. I don't run 820's, but 610's. They DO have the lighter piston, but everything else measures the same. They turn 12,500 all day, and mine aren't leaned down as much as they should be. The light piston means I'm not gouging the crankpin. I run 10 and sometimes 11 OZ pure castor. I can't comment on the wet clutch harming the keyway on the stepped crank, but I have had no issue with either Max Torque or Rev Grip clutches on the stepped crank. Anyhow, aside from the friction advantage of the single ring piston, There will be no difference in speed between a MODIFIED 50 year old 820 and a brand new 820. The numbers are the same. I DO believe that ring friction is a big deal, but that's a matter of switching pistons. I will run .024 ring pistons until I can't find any more. The single ring Arias that Louie Figone was having made was a good unit. I had one in one of the Nikasil bore 610's. No static compression, but it ran well at both ends of the track. I completely respect Rob and Bob disallowing the new block at TBO. That's a matter of keeping the base engines true vintage. I see no advantage to the new block anywhere else, aside from strength. Ted