Disable the ignition. Remove the leading plugs(the bottom ones).

Prop the throttle wide open. Check again to be sure the ignition is disabled. Have the safety pilot understand to close the throttle instantly should the engine start. Airframe chocked and brakes on. Full up elevator.

Screw in a compression gage with the Shrader valve removed. Spin the engine with the starter.

Look for 130 to 140 pound of compression on each face. If you get one bad face that means a bad or stuck side seal. Two bad faces means a stuck or bad apex seal. Most rotaries will start and run fine on 100 pounds of compression. The lower the compression the harder the starting. You can also do a leak down check on a rotary. You must have TDC marked for both housings. You must be able to hold the propeller stationary when the 100 PSI air is injected into the chamber.

That means a big person with a good grip. With a reduction unit in place the prop will not try to turn a full 180, but will turn about half that way with lots of torque. Then you are comparing the chamber leaks to a .040" hole between the gages. I built my own using a .020" hole and could get ZERO hot leak down on racing engines. 

 

The open engines all sound the same to me. I left my hearing on the mighty Forrestal. So maybe you can tell the difference. I don't know.

 

Lynn E. Hanover

 

 

> 

Pulling the blade through one revolution give me a little more that six solid ker-chunks from the engine with my 3.14
gearbox ratio.  Would that indicate a good seal, or with that just be an unreliable first approximation?

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