TNX Mike retired CNC machinist precision measuring tools not a problem. Has been by far to may years didn't want to trust my ole memory. I use to use t to clay the piston to head then adjust the shim for .010 to ,014 clearance dependent on the % of nitroSeveral ways to measure. Most require a mic. Some a depth gauge.
The quick and easy method is to use a piece of thin solder. Put it thru the plug hole and bend it to the egde of sleeve. Turn over the top. Use your mic to measure the squish of the solder.
Another is to use your mic to measure the depth of the head button. Also measure your piston at top dead center. It helps to have a bolt and a washer to hold the sleeve down while turning over the piston. Subtract the 2 and thats your head clearance.
You can use a depth mic. Pull head button off and set depth mic in plug hole. You need special adapter for this. Measure it on a flat surface. Now remount the button and measure the distance after you turn over the top. Subtract the 2.
Others use a mic gauge. These slip into the plug hole and can slide to the sleeve edge. If you cant turn it over, it is the next size down. Repeat until you can. It will be around those sizes.
Now the best is subject to opinion. They all get you to the right place. So go with what you have or can buy. BTW your looking to be around .012 on that motor.
Mike
Tom,What is the best method to determine the proper amount of shims for piston to head clearance of a nitro engine
CMB/ Rossi .67
Jim- I must be missing something here... regardless of pinch, will not the rod still push the piston all the way to TDC?... we understand thatTom,
You will want to measure at the maximum crunch point (TDC) of the piston in the cylinder. This becomes easy to do once the cylinder has been raised to eliminate the sticking of the piston at TDC...
Stick some solder in the plug hole and be done with it.
It ain't rocket science it's a toy boat..............................................
DEEP BREATHS Terry DEEP BREATHS>>>>>>>>>
I like to see the tang that way I can check right to the edge and know I am there.That's exactly what I do. You have to use a thin solder tho to get a good reading (0.016" for me) and be sure to cut the little tang left from the champher at the piston crown.
No mixing up the numbers, accounts for all the play in the rod/wrist pin etc.
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