Russian M-14 radial tach pulse setting

[litewings]

Need a correct pulse count for the tach settings in the AFS 4000 series for a Russian 9 cylinder M-14 radial engine. Have tried 9 pulses per 2 revoutions and the reading was way high. Now set to 18 pulses per 2 engine revolutions and reading way low. Mathematically, there isnt a setting in the middle of the two. Does someone know a correct setting? inputs for the system are coming off both p-leads. Pitts model 12 waiting for this to be corrected before first flight.

Also posted in another catagory by mistake.

[Shawn McGinnis]

I assume if you have both connected they are running through a 71420L RPM interface board. What happens if you only connect one through 71420L?