ive no idea at all what tachometer you bought or are making, guessing 1997 stock cluster.
the j18 on up all have 2 to 4 coil packs. COPS, (1 cop split to 2 or 4 cops) varies world wide how down by year.
no single coil to use a RPM (primary minus lug of coil) now.
I have no drawing on j18, but one.
a pro grade store bought tach can be connected to any coil and set to work, right, 1 o 4 coil setup.
now a word on cops.
are you asking how to make stock cluster tach G16 97 factory tach.
the stock tach is very crude, analog tach, it is just signal intergrater, crude as can be.
and only works with the brown wire G16, coil supressor module and only on single coil engine, and has back EMF of 50v. spikes seen on a scope.
The 50v is noise, back EMF the signal is IGNITOR output;.
to make stock tach work like this takes a 1 to 4 up-scaler, that is 1 pulse in sets 4 pulses out. a freq. multiplier. x4
and ignore the 50v.
here are my signals .
coil minus, G16 (1 coil spark engie) 0v 15v(gen voltage) 0v repeat is all it take, the back emf is not needed to make the tach work IMO.
scope.
https://fixkick.com/look/coil-prim2w.jpg
the stock tach simple measure the hit rate to 0v I think, coil charge time is integrated to make needle amp go higher, dwell time , times hit rate. 4 hits per 2 crank turns..
![[Image: tacho.jpg]](https://fixkick.com/look/tacho.jpg)
the ignitor was moved off the dash board engine side to inside each cop in 1998 in think. j18
so this signal is different from 1996/7 raw COP engines. not sure yours.
I do not know how your donor car rans its tach, nor methods.
the j18 on up all have 2 to 4 coil packs. COPS, (1 cop split to 2 or 4 cops) varies world wide how down by year.
no single coil to use a RPM (primary minus lug of coil) now.
I have no drawing on j18, but one.
a pro grade store bought tach can be connected to any coil and set to work, right, 1 o 4 coil setup.
now a word on cops.
are you asking how to make stock cluster tach G16 97 factory tach.
the stock tach is very crude, analog tach, it is just signal intergrater, crude as can be.
and only works with the brown wire G16, coil supressor module and only on single coil engine, and has back EMF of 50v. spikes seen on a scope.
The 50v is noise, back EMF the signal is IGNITOR output;.
to make stock tach work like this takes a 1 to 4 up-scaler, that is 1 pulse in sets 4 pulses out. a freq. multiplier. x4
and ignore the 50v.
here are my signals .
coil minus, G16 (1 coil spark engie) 0v 15v(gen voltage) 0v repeat is all it take, the back emf is not needed to make the tach work IMO.
scope.
https://fixkick.com/look/coil-prim2w.jpg
the stock tach simple measure the hit rate to 0v I think, coil charge time is integrated to make needle amp go higher, dwell time , times hit rate. 4 hits per 2 crank turns..
the ignitor was moved off the dash board engine side to inside each cop in 1998 in think. j18
so this signal is different from 1996/7 raw COP engines. not sure yours.
I do not know how your donor car rans its tach, nor methods.
http://www.fixkick.com