Fox .15 slant plug
 

Fox .15, slant plug, MKX carb (circa 1980)

10% nitro (Omega with extra castor added), McCoy 59 plug

Master Airscrew Scimitar 8x4 = 12,300 rpm

This engine was designed for 25% nitro, so there is probably more power available with the right fuel. Needed a hot plug to start and run well on 10%.

Jim

RE: Fox .15 slant plug
 

Fox 15 slant plug . 15%nitro 20% castor Sig fuel, 8X4 Master Airscrew , OS A3 plug. 15,500 rpm.This is the transition model with the better carb adapted by the factory to the C/L engine. I have 3 of these and they all run like this. Problem is getting a muffler.

RE: Fox .15 slant plug
 

Mine has the last carb they sold with it - MKX, I think? It is identical to the carb on my Schneurele ported .15BB. I think the lackluster performance is due to the head shim still being in place. With the figures you got it must have about the highest power/weight ratio available in such a small engine.

I have the stock muffler and this engine is the most deafening little cuss I've ever owned (well, my Cox .15 TD might have beaten it, but that was a long time ago). It's not just a simple expansion chamber either - it has two concentric chambers with perforated holes between them. I haven't dared to try it without the muffler, so maybe it actually does something, and it would be even worse without it. I am really spoiled by OS mufflers, and for that reason alone I haven't decided if I'll use this on a plane. Jim

RE: Fox .15 slant plug
 

Oh I Will get a muffler on this thing yet and use it. It is way too powerful to let languish.