Tack signal with aftermarket ignition modules

[Pronto]

While perusing around the Highway Stars website I noticed on the description of the Standard Motor Product ignition module that they warn it may not support "some" aftermarket tacks. I have mine plugged into the green plug by the alternator. Does that mean if I ever replace my ignition module with an aftermarket one my tack won't work? Has anyone encountered this issue? I'm not reading much good info on the AC Delco coils and modules, seems like they are China junk now.

 

[BRAD_PADGETT]

While perusing around the Highway Stars website I noticed on the description of the Standard Motor Product ignition module that they warn it may not support "some" aftermarket tacks. I have mine plugged into the green plug by the alternator. Does that mean if I ever replace my ignition module with an aftermarket one my tack won't work? Has anyone encountered this issue? I'm not reading much good info on the AC Delco coils and modules, seems like they are China junk now.

Yes. The issue is real. I have an after maket coil module on the shelf that works perfecty but wll not run a VDO tach gauge.

 

[Pronto]

Is there any other place to tap into for an aftermarket tach?

 

[GNVenom]

If you have a tach that accepts a "Coil" input, you could separate the coil module from the coil pack and tap into one of the three separate feeders at the base of the coil. There is a common feed under the coil pack that provides a fused positive to each coil, and the opposite wire is a "grounding" wire that grounds when the coil needs to fire. Same thing as a distributor with a set of points.
However
Remember it's a waste-spark system, so since there are only three coils, they fire twice per engine revolution, so your tach must accommodate the double signal.

 

[Pronto]

Ya, that doesn't sound promising. Hopefully my module lives a long life.

 

[GNVenom]

Well, if you can find an OEM new-old-stock part, jump on it. Even a good used one would be a good investment. Eventually, the module will crap out and you'll be stuck bigtime if you don't have a backup.

 

[Lil Truck]

I wanted a spare for my 40k module so I tried a BWD from autozone, did not work with VDO and ran bad. Returned it and bought the expensive GM from highway stars. It works as well as my stock unit. I run it and keep the stock unit stored.

 

[Pronto]

That's probably what I'll end up doing or go for the TR-6.