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1965 442 - Ordering a new Engine Harness. Car is stock except for MSD Distributer (ready to run type, no 6AL Box). The new harness will have a wire/resistor wire combo that connects to the coil, but this is not needed for the MSD Coil/DIstributer. Do I just leave this disconnected ? The MSD just requires a 12 V feed.
You can remove the wire from the bulkhead connector, solder a new 12ga wire to the pin and run it to the coil+ terminal. The other option is to run a 12ga wire from the IGN spade terminal in the fuse box to your coil+ terminal to provide a keyed 12v.
Does the resistor wire continue into the fuse panel (interior) side of the circuit, or is it just in the engine compartment?
Just the engine compartment. It does not go inside the car.
I did what Eric suggested, removed the resistor wire from the bulkhead connector. I went to my (then) friendly Chevy dealer where I knew several of the employees where they fixed me up with a few new wire ends to fit the bulkhead connector so I didn't need to cut the resistor wire. Neat & easy. I ran the new wire beside my existing wire harness and used a new reproduction wrap for the wire harness to hide all the wiring modifications I did, like an electric choke for my Quadrajet, gauge wiring, etc.
They are accessories, don't recall exactly what, I'll have to check when I get home. I do know the resistor wire and the yellow/black wire next to it (that goes to the starter solenoid) were capped with my previous engine which also had an msd distributor. It all worked fine. What does the yellow/black wire do that is connected between the coil and starter? Didn't seem to be needed.
Not being familiar with the 65 fuse box but those taps serve the same function I'm assuming as the IGN circuit. Change of plan would be to tap into the black/pink wire at the ignition switch or idiot lights junction and run that wire to coil+.
The yellow/black is the resistance bypass wire. With your previous engine using an MSD, I'm assuming your resistance wire is already bypassed to the coil.
... those taps serve the same function I'm assuming as the IGN circuit.
So long as you want your car to run in the ACC position...
Originally Posted by oldcutlass
The yellow/black is the resistance bypass wire. With you precious engine using an MSD, I'm assuming your resistance wire is already bypassed to the coil.
I'm ASSuming you meant previous, but I think I actually like it better this way...
1) I presume the terminal that the resistive wire is connected to is 12V, and this wire drops the voltage for the points. So if you connected a regular wire to this terminal it can be connected to the msd coil.
2) what is the purpose of the bypass wire? Is that also a 12v wire? Can that be used for the 12v coil?
1) I presume the terminal that the resistive wire is connected to is 12V, and this wire drops the voltage for the points. So if you connected a regular wire to this terminal it can be connected to the msd coil.
True. The pink wire on the other side of the firewall connector is a regular copper wire.
Originally Posted by craig442
2) what is the purpose of the bypass wire? Is that also a 12v wire? Can that be used for the 12v coil?
Have you looked at the wiring diagram in your Chassis Service Manual?
The Yellow/Black ballast resistor bypass wire connects the starter solenoid R terminal to the (+) terminal of the coil.
When you place the ignition key in the START position, you energize the purple wire, which energizes the solenoid coil, which pulls in the solenoid, kicking the starter gear into mesh with the flywheel, closing the high current connection between the battery and the starter, and also closing the connection between the battery and the Yellow/Black wire, and thus feeding +12V to the coil (+) terminal.
This provides a higher voltage to the coil while cranking, ensuring that the car will start in cold weather, or when the battery is low.
Note that somewhere in the 1965 range, the function of the ignition switch was changed:
Earlier ignition switches energize the Pink IGN wire OR the Purple START wire, while
Later ignition switches energize the Pink IGN wire AND the Purple START wire.
If you have the earlier version, then your car will not run without the Yellow/Black bypass wire.
So I'm thinking I have a later version since the bypass wire and resistor wire were both capped.
Bottom line - I can order the stock harness, leave the resistor disconnected, add my 12v wire for the msd, and connecting the bypass wire is optional, correct?
So I'm thinking I have a later version since the bypass wire and resistor wire were both capped.
That pretty much proves it.
Originally Posted by craig442
Bottom line - I can order the stock harness, leave the resistor disconnected, add my 12v wire for the msd, and connecting the bypass wire is optional, correct?
Correct, though the bypass wire is never a bad idea.
Thanks for all the replies, very much appreciated. I ordered the new harness, and actually they modify it for use with the msd. The resistor wire and bypass is replaced with a 12v normal wire for the coil (+). Perfecto!
Lets back up, the op stated his aftermarket gauges are hooked there and you stated the they would be used for p/windows or p/antenna. If the those terminals were only powered in the accy key position then having those items wired there would be a bit inconvenient.
Lets back up, the op stated his aftermarket gauges are hooked there and you stated the they would be used for p/windows or p/antenna. If the those terminals were only powered in the accy key position then having those items wired there would be a bit inconvenient.
No, you're not looking at the big picture.
The ACC circuit is powered when the switch is in the ACC and IGN positions.
It is off in START.
The IGN circuit is powered when the key is in the IGN and START positions
(though, as I mentioned, some earlier cars are different).
It is off in ACC.
The Indicator Lamps circuit is only powered when the key is in the IGN position, and is grounded when the key is in the START position.
The START circuit is only powered when the key is in START.
Ok, for some reason my brain was not working earlier and I had to look at an earlier full wiring diagram to get reacquainted with the earlier fuse boxes.
September 1st, 2016, 06:42 PM
