Hour Meter Wiring on a Briggs 16 HP

[Jjoness4]

I wired a simple, cheap hour meter on a B/S 16 hp mill motor.  It runs with switch on.  Sometimes I forget (old operator error)  and leave the switch on thus running up hours that are not true run hours.  Is there a way to have this meter run off "engine running" mode not just 12 volts to the hour meter.  There is a wire lug on the oil filter base.  Is that the secret? Airplane engines have a Hobbs meter that only click off hours when oil pressure is up, indicative of a running engine.  Any help here is appreciated.

[Larry]

Get a Tiny-Tach.  It displays rpm when running and hours when off.  To wire just wrap the wire from the Tiny-Tach around the spark plug wire.  Its inductive.

[Oliver05262]

 Not knowing exactly what your engine looks like, I still can see a couple ways you can rig it up. If you have a charging system on this engine, you could power the hourmeter through that so it only rang up time when the engine was charging. The other way would be having oil pressure--or lack of it--control either power to the meter or a ground for the meter.
You said you had a one wire switch on the oil filter base. If that  is normally closed--grounds a test light when the engine is off--it is probably intended for a oil pressure warning light that would go off with sufficient oil pressure. If it grounds with oil pressure, and goes open when you shut the engine down, that would work to ground a meter.
  I have also used a two terminal switch that closes when there is oil pressure to power the field on an alternator. A switch like that would send power to your meter only when the engine was running. The NAPA switch number I have in my head is OP115, but the store says that number is no good. I'll try to post back with a NAPA part number tomorrow.

[Kbeitz]

You could put an inductive coil on your sparkplug wirg that works a small relay that controls your clock.

[Jjoness4]

Thanks for all your helpful suggestions.