modified head button on PIP.45

[tmunn]

I have 2 head buttons for this engine the biggest difference I can see in them is one sticks down in the combustion chamber farther than the other , which from waht I undersatand will change the compresion ratio.

The one that was installed on the engine currently is supposed to be for 60% nitro.

I took it out and installed the one that was supposed to burn the lower nitro since I am burning only 30%.(stock head button is now installed/shortest )

Which head should i be using the one that sticks in the combustion chamber farthest or least .

Should I just try both and see if there is a difference.

The one that was in the engine had a crazy amount of compresion and the engine would not start without the plug backed out .It went in the chamber the farthest.

Terry

 

[boaterbill]

I have 2 head buttons for this engine the biggest difference I can see in them is one sticks down in the combustion chamber farther than the other , which from waht I undersatand will change the compresion ratio.

The one that was installed on the engine currently is supposed to be for 60% nitro.

I took it out and installed the one that was supposed to burn the lower nitro since I am burning only 30%.(stock head button is now installed/shortest )

Which head should i be using the one that sticks in the combustion chamber farthest or least .

Should I just try both and see if there is a difference.

The one that was in the engine had a crazy amount of compresion and the engine would not start without the plug backed out .It went in the chamber the farthest.

Terry

Terry, You need to shim the headbutton , to get whatever head clearance you want. I usally run .008 on all my motors, 21, 45, 67. 18% synthetic. Good luck.