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The old Toyota trucks were specs for adjusting the valves when the engine was hot, but that sucked. It was shown over and over again (with measurements) that the difference between the hot and cold measurements was 0.001 inches (10% for the 0.01" specs)
If you either use the 0.001" or the 10% variation spec, either way, the 911 valve spec of .0039" can be .0029"-.0049" (0.074-0.124mm) or 0.0035"-0.0043" (0.089-0.109mm).
The second set of values is the same range as the backside method, which is pretty well accepted as "perfect". both sets of values are well within the expected 0.004+-0.002" range.
Yes, i know the original question is for a BMW MC, but real world facts are that an average engine can have the valves specs anywhere between stone cold and "long enough after running the ending to find your tools, open the valve cover, turn on the work light and get to work" without really affecting anything.
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Mike Bradshaw
1980 911SC sunroof coupe, silver/black
Putting the sick back into sycophant!
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