what is the stock clearance shim for the RB C9 / C10 .21 onroads? also thats for 25% nitro fuel right?

0.8mm stock shimming - but Ive heard people say they run better on 0.9mm, but maybe thats not for RB's, either way stock shimming is 0.8mm.

This can be found in the manual....

RB is a Novarossi based engine, the real headclearance is 0.6~0.7 mm for 25%

Use the trick with a piece of solder to messure that.

Well, I just looked on the RB Concept site - the manual that comes with the engines said 0.8mm worth of shims - 2x0.3mm and 2x0.1mm or 1x0.2mm shim which totals 0.8mm.
I heard from people running 1/8 at a track I go to sometimes, that either all engines they had, or Nova's or RB's specifically (not that it really matters) ran well with 0.8mm, but felt (and showed) that they prefer to run with 0.9mm head clearance.
Ask a guy named West03 on the forums here, he might be able to confirm that.

thanks guys.