Jim,


I give some of my recommendations, from engine type and construction.

This specific engine is made (as I was told) by Sanye, like Magnum, ASP and SC engines and has the same general construction.
It was also tested by the leading R/C magazines and found to be similar in power to the OS FX and to similar engines.

I don't think this engine should differ from them by any large degree, in its ignition needs and by the book, it would seem the OS #8 and other medium heat plugs should be suitable for it.

It could be, however, that in the interest of easier operation, the manufacturer changed to a lower compression ratio.
This would require a hotter glow-plug.
The situation would be so, if the engine cannot be leaned down enough, so as not to lose much RPM when the glow driver is removed.
If an unreasonable RPM loss is persistent with a new plug, known to be good, a hotter grade plug is needed.

The 10-30% nitro recommendation (more than OS and other Sanye engines) seems to be coherent with this assumption.

The only recommended plug is the H9 Super Plug, which does not feature a heat range... See photo.


The setting of the needle valves is the last variable...

It is adjusted after the manufacturer determined the suitable load (prop size), nitro percentage and set the compression ratio.
This is the last thing that is adjusted, so the engine would run at its best, with the given constants.

The fact that with plug 'X' an engine CAN be adjusted to run, without detonating and without losing RPM on removal of the glow-driver, does not make this plug right. It could be the mixture is adjusted richer than ideal, to avert detonation, since the plug is too hot.
The engine would then become too rich in the mid-range...

This problem affects many because everybody is using the cheap A3...