Need help fixing ignition wiring - HEI, tach adapter mess

[knout]

I recently bought a 72 Mustang (302 with a 2 barrel for now) and I am trying to clean up/fix the electrical mess the previous owner left me. I have made great progress on most of the wiring and upgrades (LED lights mainly) but now i am tackling the ignition. See the car currently won't start. All accessories get power (stereo, lights, etc), but no spark. There is an HEI Distributor, an MSD tach adapter, a small accessory bar connected to the ignition solenoid, and the firewall to engine harness connector. The white cable from the tach adapter runs to the green tach cable on the HEI, the purple tach adapter cable is not used, the black tach adapter cable goes to the ground and the red tach adapter cable goes to the green tach cable from the dash/tach. The battery cable from the HEI is running to the accessory bar connected to the ignition solenoid. A new plug is attached to the firewall engine harness plug and has a single red cable (appears to be plugged into the slot on the harness with two green/red cables) from the firewall/engine harness to the same accessory bar off the solenoid.

Now can someone tell me if I am correct - I think the red cable from the HEI needs to go directly to the single red cable plugged into the engine/firewall harness.
Can someone also tell me which of the 5 cables on the firewall engine harness is the ignition power - there are 2 green/red cables (terminated together), a black with yellow cable, a red and white cable and white with red cable.
If I am correct, this should get power to the hei and ignition.

 

[Steve McMahan]

https://www.7173mustangs.com/images/72mustang_diagram.pdf

Here is the stock 72 wiring diagram do you can find the ignition source you referenced.

 

[Hemikiller]

The HEI needs a full 12V to run properly. The factory ignition lead ( Red w/Green stripe) only delivers ~7V.

To diagnose a no-spark scenario, I'd disconnect all the PO's wiring and attach a jumper lead from the Battery (+) terminal to the BAT terminal on the HEI. This will give you a full 12V to run the module properly. Check that you have a clean and solid Battery to Body to Engine ground path. Try starting the engine with the jumper attached.

If it still won't fire, it's time to dig into diagnosing the HEI itself.

 

[will e]

You can add a relay with a 12v source and the ignition wire as the trigger.