Dumb question of the day

[OldJoe54]

So, actually maybe 2 dumb questions of the day. Doing a slant 6 to 360 c.i. conversion. Most of the mechanical hook up is done, now concentrating on the electrical. Two things have got me stumped. First, refering to the attached photo. I am using the original slant 6 wire harness. I can't seem to find a match up for the connectors that are laying on the inner wheel well. I know some of these wire connect to the 3 components mounted on the side of the inner fender (shown in the photo), but I haven't verified that all of these wires attach there. So I'm not really sure what to do with these connectors at this point.

My second dumb question of the day is about the coil. If I understand correctly, the negative post of the coil connects back to the ballast resistor. But I don't find where I connect the positive post to. So my dumb question is, what am I missing here?

 

[MadScientistMat]

Typically the connectors down the passenger side are for the ignition, alternator, temperature sender, and oil pressure sender.

Unless you are using something exotic, the coil positive goes to the ballast resistor (and an RFI suppression capacitor), negative goes to your points or ignition module.

 

[Vaanth]

So, actually maybe 2 dumb questions of the day. Doing a slant 6 to 360 c.i. conversion. Most of the mechanical hook up is done, now concentrating on the electrical. Two things have got me stumped. First, refering to the attached photo. I am using the original slant 6 wire harness. I can't seem to find a match up for the connectors that are laying on the inner wheel well. I know some of these wire connect to the 3 components mounted on the side of the inner fender (shown in the photo), but I haven't verified that all of these wires attach there. So I'm not really sure what to do with these connectors at this point.

My second dumb question of the day is about the coil. If I understand correctly, the negative post of the coil connects back to the ballast resistor. But I don't find where I connect the positive post to. So my dumb question is, what am I missing here?

View attachment 1716470488

Although the color of a couple of wires is difficult to discern for sure, the pictured unconnected wiring is as follows:

• The green wire near the firewall is for the heater/air conditioner blower motor.
• The dual flat connector is for the exhaust gas recirculation (EGR)vacuum solenoid that was previously mounted on the six cylinder valve cover. It can be left disconnected or removed if not used.
• The tan wire with the female bullet connector is for the throttle position solenoid lead.
• The grey (?) wire with the aftermarket spade connector with blue insulator is for the low oil pressure switch.
• The dark blue (?) wire with the uninsulated spade connector is for the control switch for the electric assist choke element. This is tied into the J2 ignition circuit. It can be left disconnected if not used, but must be insulated to not contact ground.

Although you likely already know the connected devices, these devices are as follows:

• Blue box: Electronic speed switch, which is part of the catalytic converter protection to prevent overheat during high speed deceleration. It controlled the throttle position solenoid on the carburetor. Powered by the J2 ignition circuit. If not reused, leaving in place or removal is okay.
• Silver/chrome box: Voltage regulator.
• Black box: EGR Delay Timer. This delayed the EGR vacuum solenoid action. It is powered by the J2 ignition circuit, and triggered by the starter relay circuit. If not reused, leaving in place or removal is okay.

Regarding the coil connections, the negative (-) side of the coil is connected to the electronic control module (ECU) via the black with yellow tracer wire on the original 1975 ignition system. The positive (+) side of the coil connects to the J3 ignition circuit via the brown wire on the original 1975 ignition system.

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[OldJoe54]

Thank you Vaanth. You are way better than the 1978 Motors Manual that I've been trying to use.

 

[Mattax]

Thank you Vaanth. You are way better than the 1978 Motors Manual that I've been trying to use.

He's super sharp and knowledgeable. No way I would have known it was a '75 just by looking at your photo.

Do yourself a favor and find a way to support and protect that wire harness. The 'engine connector' is particularly vulnerable to vibration, heat and moisture damage. If there is enough slack maybe support it on the inner fender. Most (all?) years the factory supported it on v-8s along the inside of the valve covers.

You may find it worthwhile to pickup Chassis Shop Manual.

'75 wiring is a bit different than '74 or '76.
The power from the alternator had two branches before going through the firewall connector.

The main circuits look something like this on standard wiring.

Circuit codes are J for Ignition, J1 feeds the key switch, J2 for ignition run (includes power to alternator field), J3 for ignition start.
R6 for alteRnator
A for bAttery

A car with the optional electric rear defrost grid is a little different.

 

[OldJoe54]

He's super sharp and knowledgeable. No way I would have known it was a '75 just by looking at your photo.

Do yourself a favor and find a way to support and protect that wire harness. The 'engine connector' is particularly vulnerable to vibration, heat and moisture damage. If there is enough slack maybe support it on the inner fender. Most (all?) years the factory supported it on v-8s along the inside of the valve covers.

You may find it worthwhile to pickup Chassis Shop Manual.

'75 wiring is a bit different than '74 or '76.
The power from the alternator had two branches before going through the firewall connector.

The main circuits look something like this on standard wiring.
View attachment 1716470759

Circuit codes are J for Ignition, J1 feeds the key switch, J2 for ignition run (includes power to alternator field), J3 for ignition start.
R6 for alteRnator
A for bAttery

A car with the optional electric rear defrost grid is a little different.

Mattax, thank you, this is great info. I understand what you are saying about the cable support. I still have the original clips that supported parts of the original harness along the fenderwalls and firewall. Due to their age and condition, I don't know if I can reuse them, but once I get the final wiring figured out, I am going to try.