[randy500]

Today I soldered a 10k ohm resistor across the wiring harness terminals that connect to the tach along with the previously described wiring to the crank sensor.
The tach worked and responded to rpm but as the engine rpm rose the rpm on the gauge decreased at the upper rpm range.
I decreased the resistance value by soldering in another 10k ohm resistor in parallel, giving me 5k ohms resistance. The tach responded better without falling off at the upper rpm range.
The tach read low compared to my aftermarket one so I added another 10k ohm resistor in parallel which caused little difference.

Im happy as the tach does work and I think it will work better when I add 2 more pulses to the circuit by milling 2 more slots in the balancer.
The tach I’m sure was never designed to be accurate with 2 pulses per revolution that it’s currently operating at.