HEI conversion benefits

70Duster340 said
Why is the 8 pin module be better than the 4 pin one?
I used shrink tubing on the spade connectors when I installed the module. Maybe not the best weatherproofing, but better than nothing.

If picking parts, you also grab the GM coil and the cable which connects the 8-pin module to the coil, so no custom-wiring for that. The coil has a white wire for tach signal. Also clip the pickup wire and cable. The 8-pin module is inside the "small-cap" distributor. The pickup connector is not shielded but does have a locking clip. 8-pin modules will likely be available longer in the future since a 1985-95 GM part. The 4-pin is a 1970's part. In-between there were a few more GM HEI modules, like a rarer 7-pin. I don't know if the 8-pin has better tech, other than the input for spark advance, which you don't have to use. Read more on the megasquirt site.

A Mopar 1970's e-distributor will trigger the 8-pin (or 4-pin) module, since the same 2-wire VR sensor type (not later Mopar w/ 3-wire Hall-effect pickup). You must get polarity correct. Both will trigger it, but if wires are reversed the triggering will be erratic. I tested it by spinning the distributor by hand and flashing a timing lamp at the reluctor wheel. You should see the pickup teeth aligned with the mag sensor if correct polarity. Twist the pickup wires and keep them short so you don't get positive-feedback from the spark wires (self-sparks with engine off).