emeraude

Hi !, I have a few questions regarding 46 Ax's.

Firstly If i remove the headshim from my 46ax will i get more rpm? .

A friend of mine has a 46 ax and after about 30 or so flights the top surface of the piston is jet black and every time he runs the engine there is a black residue in the exhaust eventhough he has changed his fuel quite a few times , the engine runs normal with no wear on the glowplugs is it normal for the piston to turn black

Thanks

dcwolf

Removing a head shim will increase the compression ratio and may increase the performance of the engine. However, I would not advise it in this instance. First of all, the increase in performance will be very marginal. Maybe a couple hundred rpm. Secondly, this engine only comes with one head shim. It is actually a head gasket and not a shim. Removing it will most likely cause the head to leak. Lastly, all other things being equal, increasing the compression ratio will advance the timing of the engine and may lead to preignition(detonation).

It is not uncommon for the top of a piston to turn black. The black color is cause by carbon deposits from unburnt fuel. The richer the engine is run, the quicker it will turn black. Normally, it will not cause any problems, but it can build up over several gallons of fuel. In extreme cases, it should be removed.

Hope this helps.

David Wolf, Senior Product Support Supervisor
Great Planes Model Distributors
3002 N. Apollo Dr. Ste. 1 Champaign, IL 61822 USA
Phone: 217 398-8970
Email: [email protected]