I am finally wiring up my big block in my 74 C10. I am installing an MSD distributor and think I e figured out the starter wiring. I tra ed the yellow wire from the starter and it is spliced to a pink wire to the firewall and another yellow wire to the distributor. Is this pink wire a resistance wire? And if so di I need to replace it to go to the distributor or is there some other wire I can use for the distributor?
Also, I have 1 sensor on each head. I think the drivers side sensor is water temp and the green wire goes there. But the one on the passenger side I'm not sure about. Maybe oil pressure warning light? If so what color wire goes to it?
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The YEL coming up from the solenoid is unnecessary - you can remove it.
There is resistance in the PNK/BLK wire that comes from the ignition switch, goes through the firewall and supplies the coil primary. But, I don't believe it's like an actual resistor that is spliced into the wire. I'm pretty sure the resistance is created by the decreased cross-sectional diameter of the conductors - but only in that part of the wire that runs from the bulkhead connector up to the coil.
From the ignition switch down to the cab side of the bulkhead connector, the wire (it's just PNK on the cab side) is 12 AWG. On the engine side of the connector, is is reduced down to 20 AWG - and stays that way until it connects to the coil. The reduced cross-sectional diameter might be how the resistance is created.
The whole idea behind this resistance is to reduce the voltage at the coil primary - while running - to around 9.5 volts (which increases points contact life). On the other hand an HEI distributor fires the plugs best when supplied with 12 volts.
The YEL lead from the solenoid was intended to temporarily supply the coil with a full 12 volts - only to aid in starting. Then, when the key was released from the START position, the 12 volt supply was cut off and only the 9.5 volts - from the ignition switch (through the resistance wire) - was left to supply the coil.
Anyway, I would say you should:
1. Remove the YEL lead coming up from the solenoid altogether
2. Remove the 20 AWG PNK/BLK coil primary feed from the firewall to the coil
3. Replace that section with 12 AWG wire (that's what is used for factory HEI applications)
On this;
Also, I have 1 sensor on each head. I think the drivers side sensor is water temp and the green wire goes there. But the one on the passenger side I'm not sure about. Maybe oil pressure warning light? If so what color wire goes to it?
You'll have to provide more detail - a photo would be even better. But it's not an oil pressure sensor. There are no oil passages in a SBC cylinder head.
The heads are interchangeable. Imagine removing the RH head and bolting it to the LH side of the block. If the mystery sensor is in a hole that is located exactly where the other coolant temperature sender is...it's just an unused coolant temp sender. Probably there to plug the hole.
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