Spiral,


The first thing you must do is to change the fuel you are using...

Morgan Fuels, the manufacturer of 'CruelPower' specifically recommends their own 'Omega™' fuel for ABC/ABN type engine, which your Evolution engine is.
Omega has 4.9% castor oil and 12.1% synthetic oil (a total of 17%).

American made synthetic oils in general (Cooper's Ester based oil is an exception) offer a lower lubricity, compared to castor oil.
Klotz rate their own BéNOL at 10 and their Techniplate KL100 at only 5. This means your engine will wear excessively when you use fuel that does not contain castor oil.


Also, castor oil has a 100°F higher flash-point and even more than that higher burn-point. This means you engine will very likely fry if you ever expose it to a 'lean run', with your current choice of fuel...

The running qualities of any engine are also much better with a good measure of castor oil in the fuel... I believe many people consider this hobby less enjoyable, or have even strayed away from it, only because of trouble in engine adjustments and running, due to using all-synthetic fuels and never experiencing the qualities of castor oil...


... Your description sounds like your engine is being run too lean...
The main needle must be adjusted 100-150 RPM rich of maximum, with the plane's nose pointed straight up.

There is no corresponding number for level attitude. This adjustment must relate only to the nose-up attitude!


I am sure Barry (blw) might disagree, but I think the OS A3 is too hot. You need a medium heat plug for this engine and the TowerPower is a good candidate.