OK... so I have been messing with this engine alot over the last week. Final tach numbers as of Friday night was 20,100rpm on a APC 5x3 running a brand new #1 cylinder/piston( twin bypass NOT TD), regular glow head with 1 head gasket on SIG Champion 10% nitro all castor, either 20 or 25% lube. After reading over my old "Norvel Killer" thread I remebered AJC's chart about intake timing, Japman thought that the little engines would be happier with the intake closing sooner than 30/35degrees ATDC due to the short intake track they have. I made a rotor( it sure is nice to just be able to make a different rotor than a new crank) with the intake closing 20degrees ATDC. The engine HATED it and barely ran at all..go figure! I will go the other way when I can make a different rotor this week with 40 degrees in it.
Hi Tim,
I am very curious about what you find out- I'll be making a cox 049 disc rotor intake engine for my contest plane when I get back to Japan in 3 weeks or so. I am surprised that 20degrees didn't work. I was planning to start my experiments with intake closing at 0degrees ATDC and then 5 deg or so. As I said before I would have thought that less closing lag would be better but there could be a number of reasons why a particular engine may not like it, some of them vexious
I have been thinking broadly that it would be good to make the discvalves in some convenient way i.e a holesaw so I could smack out 10 blanks to try a few different timing configurations.
Stefan