Tach reading

[Profileair]

My 1964 E model with 200hp tach always reads real time. If I fly 1 hr at 65% power the tach reads 1 hr. it acts almost like a Hobbs meter. Any thoughts?

[aaronk25]

What rpm are you running? I thought the mooney tachs are calibrated off 2500rpm, so if you ran 2300 it should show less than hour. That's the way my j is so I'm guessing yours is that way too. Just a guess maybe someone here could confirm it for us.

[N201MKTurbo]

Is it the stock tach? If you can see the part number on the tach, you can look up what its recording RPM is.

[jetdriven]

IDK about the older Mooneys, but the J has a 2566 RPM recording speed. Somebody replaced our M20J tach in 1982 with a 2300 RPM unit,  and after flying a few long legs the tach recorded more time than the hobbs, so we changed the tach out, and subtracted 440 hours total time from the airframe and made a log entry documenting that.

[carusoam]

So the last piece of my M20 C I have still is it's tach. It has the mooney logo on it and inspection stamps a numbers

660011 1

585 J1 J6

SW 5 32

SW 220

And an arrow indicating rotation...

Can't make sense of the rpm standard. Much of the ink is missing and assumptions made.

Is that an oil lube cup at the top of cable input? If it is, I understand why I have this memento!

Best regards,

-a-

[Profileair]

Thanks for the info. I'll check the part # to see if I can find what it's calibrated at. I do run at 2400 or 2500 most of the time but sometime run slower. Doesn't seem to matter. I'll pay more attention on the next flights.

Thanks again

H