I'm in the process of wiring a buddies SBC 64 for an HEI and had intended to replace the original resistor wire from the multi pin connector with the larger standard wire to supply power to the HEI in the run position. Then I started worrying if the original under dash wire to the ignition switch is heavy enough wire to carry the load,does anybody know if thats the case? Another issue is that he had installed a high torque ministarter that only has a 2 post solenoid so there is no 3rd terminal to supply power to the ignition while in the start position, I know some guys have gotten away with not supplying that power and depend on the ignition catching it when released to the run position, I'm not very receptive about that method. I intended to see if I can find a 3 post solenoid to replace the one on the starter, but if the underdash wire gauge isn't heavy enough to support the HEI then I'm considering running a small gauge wire from the multi pin connector to trigger a relay with heavy wire to the HEI and if I use a 2 trigger relay I can use the available post on the 2 post solenoid to trigger the relay while in start.Does this sound like the way to go or is there an easier way that doesn't involve diodes?
Wiring 64 Impala for HEI
- Thread starter 427John
- Start date
I would check the resistor wire during cranking, if it has voltage just replace the resistor.
That was the plan to just replace the resistor wire with standard wire in the underhood end of the harness but was unsure if the underdash end of the harness going to the ignition switch was heavy enough wire to handle powering up an HEI.I was under the impression that the underdash end of that wire to the bulkhead connector was standard wire and that only the underhood portion from the bulkhead connector was the cloth wrapped resistor wire. If the underdash wire guage is sufficient for the HEI I'll just stick to the original plan and either find a 3 terminal solenoid for the starter or use a Ford solenoid as boxerdog suggested.
Find a circuit hot key on.
Correct me if I'm wrong but isn't power supplied to the coil from the 3rd terminal on the solenoid thru the purple wire in the start position? Isn't that how they bypass the resistance wire to supply 12 volts to the coil during start?I was under the impression that power was only supplied to the coil thru the resistance wire when in the run position and that power to the coil was supplied thru the purple wire from the solenoid in the start position. I had considered splitting the start wire from the switch to the solenoid to supply power but would it get feedback from the other wire in the run position causing the starter to crank while in run position requiring a diode to prevent it?
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The extra wire from the starter is just for 12 volt bypass for hotter spark on startup, the other coil switched wire is always hot with switch on or cranking.
63impaloligist
Well Known Member
You would need a mutually bussed ignition switch. Factory ones aren't. That's one of the two reasons why the bypass wire is there. Learned this the hard way on my Nova.
I would test with a test light with the starter feed wire disconnected to start with then I would know how to proceed.
63impaloligist
Well Known Member
Use one of these. Use the two post starter. You'll have to change orientation and crimp new terminals on the factory harness but this comes with the terminals and it's a fairly simple deal. Nothing like getting it done correctly the first time. And having people on this site that can help.
I have wired three Chevy engines that I installed hei. The one way is from fuse panel switch powered thru firewall to hei battery slot. No other wires needed anywhere. Only one existing crank wire needed on starter,yellow. Remove purple. This was on my pickup and wasn't concerned about seeing that wire. The other way to hide wiring that I did on my 63 is replace resistor wire from outside bulkhead connector at drivers hood hinge area to hei battery and can be in wiring harness. That wire can be a next step heavier guage then other wire's in that loom Again purple wire is not needed on starter . You can buy a factory connector that snap's into hei battery slot on distributor. I had saved my old 63 bulk head connector's and used a different pin spade with regular wire to be able to completely remove resister pin. These pins are available in parts stores.No need for any other wiring or ignition switch. Have run the pickup for years with ignition switched power from fuse panel ( heater fan fuse) to hei with no problems . Only one crank wire to starter and of course battery cable to starter. You can buy these to snap into hei batt and tach terminals. Secure and keeps connections clean.
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I believe there is a spade on upper left fuse panel on 64 that is marked ign fused. Use that for hei power. Just have to see if it does switch on and off with key ,if not motor won't shut off with key.
Sure is!!!
Great info guys, answers a lot of questions. I was getting confused because I've seen rigs where it worked fine and others where it didn't. My 64 K20 will not fire while cranking until you let the switch back to run so apparently it is not one of the mutually bussed switches. I'll check his Impala and see what the switch looks like there, is the existing wire going from the switch to the bulkhead connector heavy enough guage for the HEI or should I upgrade to heavier wire?I like getting the mutually bussed switch and running the 1 wire to the HEI and eliminating the purple wire, that sounds like the best option, clean and simple.I've already got the HEI pigtail and plan to incorporate the power wire into the underhood harness at the bulkhead connector, if necessary I will increase the wire size in the underdash harness from the ignition switch to the bulkhead connector, if the switch he has isn't already a mutually bussed one I will get one and will bury the purple wire in the underhood harness just in case he ever wants to switch back to stock stuff.
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