Distributor/Tach Question

[NoVaCJ8]

Hello,

I installed an HEI distributor in my '84 CJ-8 with the 2.5L engine https://performancedistributors.com/product/amc-4-cylinder-dui-distributors/. The coil is incorporated into the HEI distributor, so the factory coil is no longer used. I also installed an aftermarket tachometer, which I hooked to the tach terminal on the new distributor. The new distributor and tack are both working fine.

My question is about the 2 green wires on the tach side of the original coil. I also hooked them into the tach terminal on the new distributor, but I don't think the computer is reading that signal. The reason I think that is because the "up shift" light is no longer illuminating at higher rpms.

I don't really care about the "up shift" light not working, but my concern is whether the computer uses the RPM signal for other actions it might make.

I asked the distributor company what the computer is expecting, and they said "It should be receiving a 12 volt square wave from the negative side of the coil."

Anyone have any ideas?

 

[spankrjs]

Your emissions computer is incompatible with aftermarket HEI distributor.

 

[Kane]

You computer controls timing advance and fuel functions. You eliminated the timing feature but you may be right. If the computer does not know the rpm it could richen the carb when you don't want it to.