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Old Oct 28, 2012, 12:21 PM
Brutus1967 is offline
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I convince things to work
The Netherlands
Joined Nov 2009
4,622 Posts
Not really an expansion coefficient, but an experience factor. I know, that exhaust valves with a length of 50 cm (20") typically expand some 0.3 to 0.4 mm when at operating temperatures.
The length you mentioned is close to 1/20 of that....
Should not be too far off. It is measurable anyway:
If I am to do liner measurements, I need to measure to an accuracy of 0.01 mm, and from liner diametres of 50 cm and over, I am not allowed more than 10 deg C temperature difference between liner and rod, in order to prevent mis-measurements.
I have checked this, and indeed, with bigger temperature differences you will get repeatable deviations in the order of 0.01 mm per 10 degrees.
And the bigger the engine, the more carefull you have to equalize temperatures
(very inconvenient if you're time pressured, the liner is 70 degrees and you have to wait until the rod is the same temperature, apart from having to wear gloves when handling a micrometer....)

Brgds, Bert
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