I am replacing a burned out crane ignition system on my 260z with a GM HEI module and will be installing a rebuilt distributor. I have found a lot of useful information on this forum, but still have one question. When connecting the pickup leads to the module the discussions refer to the positive and negative leads. My disributor has a plug with a maie and female connector from the pickup. My question is this: which is the positive lead and which is the negative lead?

Thanks

What color are the wires? Red is positive, from the magnetic pickup (reluctor). If you have a rebuilt, they may have spliced wire extensions on that are the same color but you might be able to see the original color up by the pickup.

From what I've read, the other way to find out is to just hook it up and watch your timing mark. Apparently, if it's connected backwards the timing will be erratic and unstable. If you get an unstable timing mark, swap the wires and re-time.

Make sure that you have a good ground to your mounting posts, they are the electrical grounding points for the module internals.

Thanks for the advise. Both wires are black all the way back to the pickup. I will try hooking it up and see what happens. Needed to know if hooking it up backwards would harm the module.

It won't hurt the module on the G and W pins of the HEI module, where the reluctor wires connect. The module just looks for a voltage signal going from negative to positive across those two pins and fires at the crossing point. If you hook it up backwards the crossing point is off and weak (it will see a strong positive to negative signal instead) so you get poor timing control.

This is for the 4 pin module, I think the 7 and 8 pins are opposite, working from a positive to negative voltage. Either way, if you don't know - trial and error.

The B and C pins probably need to be connected correctly or damage might occur.