TEST THE FIT of a Nitro RC Racing Engine:

25 years ago, I was told of the way an accomplished rc racer tested his engines to determine if they had The Perfect Fit. Since he was by far, the BEST MODELER in the USA at that time, I listened.

Now to the way to test the fit of the piston/liner, to see if you have a great fit and seal.

I assemble the finished engine. I apply a drop of “silicone platelets” to the piston surface on initial assembly. You can get this at Boca Bearings as (Midas Touch Lubricant). I turn the engine over several times to coat the piston and imbed the Teflon Platelets in the piston. I put a little bit of methanol in the engine to clean out most of the oil residue.

I put in the Glo Plug into the engine. I check the seal of the liner and piston by rocking the engine back and forth over top dead center. If you can’t rock it back and forth over top dead center without loosing the seal between the liner and piston leaking down, for at least 20 bumps, you don’t have a great fit.

Once you find that you have an engine with a great fit, run the engine in your model. You want to get the engine VERY WARM for a short period of time. Then run rich for a short period, then run VERY WARM, etc. Several cycles like this will allow the metal of the piston and liner to find their set and you should have a GREAT ENGINE.

I would suggest that you re-try the bump test AFTER you run in the engine to make sure that the seal lasts.

This test will be one of the best tips you will ever learn and will accurately predict the success of your engine build.

The fit is “Far More Important” than any timing numbers or ANYTHING ELSE, and will be your primary indicator of a great engine.

This test shows the liner/piston roundness, the seal of the liner to the case, and the seal of the head to the liner.

Invite your friends to join our Mailing List on the http://Engine-Analysis-Software.com webSite and get periodic technical notes.

THIS TIP IS THE MOST IMPORTANT PART OF BUILDING ANY NITRO PERFORMANCE MODEL ENGINE !!!!

Marten (Marty) Davis

Owner – Engine-Analysis-Software.com

7 time National Champion

Member of Hall of Fame IMPBA

Many National IMPBA Speed Records