RE: O.S. .46 AX Shims
I will reread the AMA 424 / 428 rules again but I think it says “Gaskets” not “Shims”. In APRA we interpret that as any head gasket because the engines we run already have head gaskets / shims. They do not, however, have sleeve shims or gaskets and therefore based on the AMA rules any engine found with sleeve shims would be judged illegal. But as Dave says it’s a club race and anything you guys agree on is ok. Just for my own info do you guys who race sports 46 size engines with props other then 9x6 get a variance on your AMA sanction. There is no 3 pole course for engines larger than 40 and the 2 pole course is considerably longer for engines above 40.
Barry