The 4.2 x 4 is "The Prop" unless you want to run custom made. I ended up shaving the blades a bit thinner to help with heat issues.
Does this engine have 180 degree [or more] of exhaust timing...? [There is also a lower, "sport" timed version.]
Either Bill Hughes or Doug Galbreath might know about Nelson heads. Bill is the US distributor of G&Z [almost the same as CS].
There is also a C/L Speed forum at Delphi Forums where several flyers with lots of experience hang out.
They can give you specifics down to the ,001" about how to be successful. In a nut shell, you want to start the tuning process from the under compressed and under propped side of the equation and your goal is to get great runs without generating too much heat. You'll melt out the silicone pipe seals and melt the epoxy insulators right out of the glow plugs if your set up is too aggressive. The wrist pin circlips de-temper from hot runs and wedge themselves between the piston and liner.
This sort of stuff is avoidable if you know how to proceed with caution. Knowing how to set a needle and mix a batch of 75 / 25 fuel is not enough. Being able to control the mixture in flight would be a tremendous advantage, plus you can abort a bad run ASAP.
Last edited by combatpigg; 06-07-2014 at 09:09 PM.