I have an older Merco 35 stunt engine and was wondering if all castor fuel should be run in it, I'm thinking about 22% castor, and maybe 3-5 %  synthetic to keep it cleaner.
  Also I have this fuel in 10% Nitro, also what would be a good prop to use??

   T I A...

   Thank ya' Randy...

Hi Gil,

If it is the older Red Head they were excellent stunt engines.  Frank Warburton used a RH .35 in his Tony to win the British NATS.  And it is no small model.  Like Randy always says, 28% oil with about 20% castor.  Sounds like you are on the right track.  For stunt use a 10X5, 10X6 Top FLite paddle blade style prop seems to work good.

BIG Bear
RNMM/AMM