Ron. Andy,
following your request for more info i have just been speaking to Alan Thorne,
he also had problems with the standard tacho on his 912 under-reading right
through the scale, max difference around 400 rpm less at 4800 indicated,
discovered when he borrowed an optical tacho.
He has also noticed that when oat's are generally quite hot, the tacho
appears to under-read too. This hasnt been quantified but his europa's
performance didnt drop at all, although the tacho indicated it should. I
recall something in a newsletter about a factory plane during hot conditions
that had a similar problem, with lower than normal indicated rpm, apparently
fixed by oiling throttle cables: Perhaps it was the tacho at fault then.
chus, dave
kit67
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