Has anyone tried controlling engine speed with the carb left fully open and adjusting the compression setting for engine speed?

It sees to work well on my paw 06 green head using home made fuel: 1 part pump diesel 1 part 30 weight motor oil and 1 part cheap brand starting fluid. This is a nice smokey fuel I blend the fuel in 6 ounce batches in a mason jar.

The engine will not idle super slow but will run slow enough to be functional. I have not devised a way to connect the servo to the t bar. These test were done on a bench. The engine requires an electric starter to start it but runs well on the blend and responds well to compression adjustments for engine speed.

I have thought about that as I have an engine with just a venturi that I might want to fly RC.

You would need a pretty strong servo for that, and the contra usually will not back out far enough once it is up to temp.
The later PAW engines have a common crank-case for CL and RC, so you can easily drop in a carb and then it will throttle well.

On my paw the screw backs out on its own and seems to turn fairly easy so i figure why not put a servo on it.

THIS WORKS LIKE A CHAMP ON THE 049-051 COX DAVIS HEAD
PROCEDURE REMOVE THE SPRING UNDER THE COMPRESSION SCREW, ATTACH SERVO ARM TO TOP OF THUMB SCREW CAN BE TURNED BY 1/4 1/3 TURN BY A SMALL SERVO VERY LITTLE LOAD ON SCREW ENGINE SLOWS ENOUGH TO LAND NO RC CARB NEEDED MARTIN
WORKS OF COURSE BY LOWERING COMPRESSION MARTIN

The PAW 06 has a real counter piston, unlike the Davis heads with a teflon disk, there is a lot more force involved to increase the compression on a PAW and it will not back out all the way once up to temperature.

Mr Cox, granted think this will only work on the Cox no load ,rather on on ohters which is a lot more load on a contra or even regular contra in head design martin