Phoenix8990

I wanted to confirm the accuracy of my tach using an old dwell tach I had and realized I couldn't hook it up. Is there any way to connect one?

Steve

oldcutlass

To the tach terminal on the HEI. You probably won't see a dwell, but the tach should work.

joe_padavano

You definitely won't see dwell with a connection to the TACH terminal. You WILL see RPM on the tach, however. The TACH terminal on a GM factory HEI distributor emulates the same signal that you'd get at the negative terminal of the coil with a conventional points-type ignition.

Note that is says TACH right on the coil cover on the distributor cap. A normal female spade terminal with plug into it. Most dwell/tach units made in the 1970s came with a short jumper wire for exactly this reason.