new engine wiring harness install on 1964

[mikeshome]

Doing an engine swap 350 with HEI ,Bought a new engine wiring harness that plugs into firewall by heater box. There are 3 wires at the starter purple trigger wire a small yellow on other small solenoid post that joins the red at the HEI and a black with a large grommet. Does the black go on the positive with battery cable ?When i do this temp light comes on and i have low power at HEI plug all the time and full power at crank only. I know green is temp wire i am not using. If i use the old HEI wire from the fuse box that old owner had and leave the black at starter off truck will start.

[ray_mcavoy]

I think you might have the wrong engine harness.

When you say the temp light comes on, I assume you have a warning light dash cluster, not gauges, correct?

If so, that new harness is meant for a truck with a gauge cluster. That black wire is part of the battery gauge circuit and does connect to the positive battery cable stud on the starter solenoid. But that only works if you have a gauge cluster and the rest of the necessary gauge style wiring.

The correct engine harness for a truck with warning lights will not have that black wire. Instead, it will have a second green wire (usually light green) that goes to the temperature switch (so 2 wires instead of 1 going to the temp switch). Plus, the warning light harness will have a blue wire going to the oil light switch (that wire is absent on the gauge harness).

[mikeshome]

Thanks Ray i was wondering that. Was wondering why it even has the yellow going from solinoid to HEI plug with the red.

[ray_mcavoy]

You're welcome.

Regarding that yellow wire ... as you probably already know, that was originally used with the points ignition system. It's connection to the "R" terminal on the starter solenoid allowed it to provide full battery voltage to the coil (momentarily bypassing the resistance wire) for a hotter spark during cranking.

When companies make harnesses that are configured for HEI, they basically just replace the resistance wire with a regular wire (commonly pink) that supplies full voltage to the coil all the time. The fact that they also leave that yellow bypass wire in there is somewhat redundant.

[mikeshome]

Thanks again and I looked at my invoice and it says for gauges.Will get another one