A-65 to A75 upgrade

[bobbuilder1313]

Recently tore down an A-65 to upgrade to A-75 (per Continental Bulletin M-47-16). The pistons are five ring pistons (four above the pin, one below). These are from a Continental A-75 from the factory. Now for the question. According to the service bulletin, you are supposed to use three ring pistons, #40577. Can I legally use the five ring pistons as Continental did or must I use the three ring ones. I assume that the five rings ones are better pistons, better oil control as such, but I want to be legal here. Also, what is the best metal prop to use to get the rpm's up near the legal 2600 rpm's to generate the 75 hp. i have a Sensenich M74CK46 metal that I can re-pitch.It's going on an Aeronca Champ. (don't hate me.....it's strictly a business deal to use a Champ.)


Bob Hunt

 

[Renkou1]

 

[cubdriver2]