Dan Thomas wrote:
Michelle P wrote in message link.net...

Sami,
it is allowed to be off by 5%. this is 40 rpm at 2000 or 50 at 2500.
While it is outside limits most places will placard the difference and
call it good. getting a mew one it may not be much better.


5% of 2500 is 125 RPM, not 50. His tach is still out of limits,
though. In Canada the limit is 4%, measured at the centre of the
cruise RPM range.
Most tachs in singles are the magnetic-drag type, and the magnet
weakens with age, so the tach underreads. Replace it, but I think you
need the green and red markings to identify safe ranges; does the
electronic tach have such warning devices?

The Horizon P1000 electronic tach has a red LED that comes on when you exceed
the maximum RPM. It also has LEDs for grounding of the P-leads, probably some
other warning indications I've forgotten.

http://www.horizoninstruments.com/prod01.htm

Google for my postings about installing on my Cherokee long ago.

- 1 RPM resolution and accuracy.
- no more worries about deteriorating accuracy.
- totalizer runs 1:1 in real time any time RPMS over 800.
- you get used to the jitter in the display (caused by 1 RPM resolution).
- directly displays RPM loss during runup as you ground each P-lead.

Dave
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