MSefi.com read only forum (Jan.15,2018)

i am in the process of building one of these units and I am having trouble with what tach circuit i should use. i currently have a 4 pin gm hei distributor that doesn't have a hall effect or a reluctor built into it. i think the only option that i have is to use the (-) side of the coil which is located in its cap. i think this distributor was discontinued in 1981, so its an older version. i found a drawing on this site
but i have read that using the coil is to "noisy", is this correct? and i am curious what the voltage range is while the engine is running.
Any help sure would be appreciated, I'm really confused.

check out the attached marked up schematic.

Thanks
Ivan

If it is a GM HEI distributor is has a reloctor wheel it is in the bottom of the housing It has 8 points if it is for a V8 and 6 points if it is for a V6.
for the tach signal look in the cap where the wires connect there are four terminals one of them is marke tach use that for the tach. signal.