[pb101]

Hello,
I just replaced my old dash harness to a new M&H one. I tried to start it turned over but no spark. Figured I would replace my old Delco HEI also. Bought a new Pertronix HEI and installed it and still nothing.
The car is a 65 GTO with a 66 389 in it. It has a hi torq mini starter. The car ran fine before I replaced the dash harness and distributor.
Thanks, Paul

[ho421]

I fought with one of those redesigned pertronix pickups for a month last year. Same issue. No spark. Removed and replaced with new points and condensor. Started right up.

[steve25]

Are you getting atleast 9 volts to the distributor when cranking the motor over?

[pb101]

I was just checking for power in the battery side plug for the distributor with a test light ( I haven't checked for how many volts are coming in ) with the key in the on position the test light lights up, when I start to turn the motor over the test light goes out. So I connected a wire from the battery connection on the distributor directly to the pos side of the battery and it popped through the carb without turning the key , just connecting the wire.
Thanks

[pfilean]

Because you had problems after just replacing the wiring loom and before you replaced the HEI the problem would likely be in the loom. Find that problem before you replace other parts and make more potential problems. Sounds like the new loom does not have power to the ignition with the key on. In your 65 the ignition switch moves power to a different wire when in cranking mode that does not have a resistance wire. Then when you move the key back to run mode the power is changed to a wire with proper resistance. HEI ignitions generally don't like getting operating power through the resistance wire. Are you sure this new loom is made for a HEI ignition and not the original points?

[pb101]

Double checked with m&h tech and they said there is no difference in the dash harness between hei and points. They thought maybe the ignition switch is bad and to check power at the switch for the yellow wire.ill try that next

[pb101]

Got the car running. Previous owner spliced the ignition wires together to run the hei.
I made the splice under the hood. New engine harness for hei coming next week.
Thanks for the help and suggestions.
Paul

[pfilean]

Yes, there should be a difference between points and HEI looms. Factory looms in 65 would have the resistance wire spliced entirely within the taped portion of the loom. All you see at the coil end is one black wire to attach to the + coil terminal. That wire does not supply 12V when running. For HEI you should have a 12V supply. If you have the GM factory coil-in-distributor you don't need the resistance wire. However if you have a Pertronix (and probably other aftermarket system) you should still have the resistance wire as the coil is probably not intended to get 12V supply. Maybe your loom supplier means that the factory transistor ignition does not get a different loom. It could be that that factory system was intended to run on the lower voltage supply. I don't have enough information to know that. But if you have a GM HEI or some after market system you may find the replacement loom may not work as delivered.