Finding 12 volts to run HEI in a 64

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Old Apr 1, 2010 | 01:04 PM
  #1  
1964F85's Avatar
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From: York, Pennsylvania
Finding 12 volts to run HEI in a 64

Hi, I just went with the HEI conversion and was having quite the time of trying to find a full 12 volt source for power to the coil when the car ignition is turned to start and run. I see 12 volts in the on position, but every last terminal drops to 9 volts and change when cranking. The car refuses to start. However, I can hot wire direct from pos. cable end to dist 12v in terminal and it starts right up, no problem. BUT you can't shut it off with the key then... A friend suggested running a jumper from the S terminal to the 12v in at the cap... That only fired the engine up, when the engine started, it immediately died. Where can I get a solid 12 volt source on this old car and do I have to rig up some sort of relay mess..? If so, then how would I wire it up to work properly with the key? Any suggestions would be great! , Cheers, Mike
Old Apr 1, 2010 | 01:33 PM
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Hookup a relay to run off the ignition switch
Old Apr 1, 2010 | 01:42 PM
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Same question here. I am not starting the car with the ignition though , I turn the key to run then push a button to start. I wonder if I can run a wire to the coil from one of the two 10 ga wires at the push button , But which one ?
Old Apr 1, 2010 | 01:52 PM
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Aren't you able to use the original coil power wire if you bypass the resistor?

You just need to find a wire that has power during crank. Disconnect the starter wire and check all the power wires while someone turns the ignition to the crank position look for a wire that has power in both the crank and run postition.

Last edited by 66ninetyeightls; Apr 1, 2010 at 02:01 PM.
Old Apr 2, 2010 | 06:49 AM
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1964F85's Avatar
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Hi all, thanks for the replies. Another friend stopped by and we did manage to get it sorted out. There were 2 wires going to the positive side of the coil; a black one and some sort of cloth covered whitish one. I ended up using the white wire, directly to my HEI power input. The car fired right up. I was reading something about the pre-67 cars having something weird in the way they are wired. Anyway it works correctly with the key now and I need to remove the wire I fished in thru the firewall. I guess I should ultimately someday add some sort of inline fuse, ya think? Cheers, Mike
Old Apr 2, 2010 | 06:50 AM
  #6  
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Originally Posted by 66ninetyeightls
Aren't you able to use the original coil power wire if you bypass the resistor?
Yes, and this is by far the easiest way to do it. Unfortunately the resistor is actually the wire itself, so you need to replace the wire. There are two wires going to the +side of the coil, one that is copper and provides +12V in the START position and one that is resistor and provides reduced voltage in the RUN position. Replace the resistor wire and hook both of them to the BATT terminal on the HEI. Problem solved.

The fact that you're seeing reduced voltage during cranking is not unexpected.
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