How to Test THE FIT of a Nitro RC Racing Engine:
I was told a secret by a very accomplished rc racer how he tested his engines to determine if they had The Perfect Fit. Since he was by far, the BEST MODELER at that time, I listened.
Following is that secret to the way to test the fit of the piston/liner, to see if you have a great fit and seal.
After assembly of the the engine I apply a drop or two of “silicone platelets” to the piston surface. The Teflon Platelets is available at Boca Bearings as (Midas Touch Lubricant) After I turn the engine over several times to coat the piston and imbed the Teflon Platelets slightly, I put in some methanol 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.
After you find that you have an engine with the great fit, run the engine in your model. Get it VERY WARM for a short period of time. Then run the engine 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 method for the seal of the engine, will be one of the best tips you will ever learn and will accurately predict the success of your engine build.
This fit is “Far More Important” than any timing numbers or ANYTHING ELSE, and will be THE primary indicator of great performance.
All considerations of the engine build are built are built into this test. The liner/piston roundness, the seal of the liner to the case, and the seal of the head to the liner.
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YOU HAVE JUST RECEIVED THE MOST IMPORTANT TIP IN BUILDING ANY NITRO PERFORMANCE MODEL ENGINE !!!!
Marten (Marty) Davis
Owner – Engine-Analysis-Software.com
7 time National IMPBA Champion
IMPBA Member of IMPBA Hall of Fame
Many National IMPBA Speed Records