I got a laser one for that purpose. Just put a little piece of reflective
tape on the flywheel and aim the laser at it. I think I paid about $40 for
it, maybe you can rent one.

"Jeff" wrote in message
news:1125697229.b7089977ad2a2f0c9398117204ee43cc@t eranews...
boater435 wrote:
I belive my tach is not reading properly. I have an albin 27 family
cruiser with a lehman diesel the rpms seem to exceed the redline by
alot 500 to 800 rpm (guessing) the tach stops at 4100. I don't think
the engine would go this high. I am trying to find something to check
the rpms so I can calibrate the tach or repitch the prop. Any help
would be appreciated. Paul, Cape Cod, MA

There is a little gadget that has a rubber tip and records revolutions
sort of like a micrometer or caliper. A friend had one and helped me
calibrate a tach that was not reading properly after a pulley had been
changed. You hold it against the crank pulley for a minute and it tells
you the revs.

Somewhere I have another that I found at a flea market, but can't find it
now. I seem to remember the word "Starette" stamped on it - they made a
lot of small instruments.