Under Hood Wiring Help Needed 81 GP

[81GrandPrix383]

Hi folks,

I need your help here.
I have my newly built 383 in my 81 Grand Prix which I bought as a roller with no motor.
It originally came with a V6, then the previous owner had a small block chevy in it.

The car's wiring is a bit of a mess and I'm lost.
I need someone to tell me where the wires go that are in the harness.
This is what I have:
2 large red wires I think they go to the starter but to which spot big or little.
1 Large orange wire that I'm sure goes to the distributor.
1 small brown wire
1 small brown wire with a white stripe
1 small green wire
1 small tan wire
1 Large purple wire

I'm lost and this is all I need to start this car.

Thanks.

 

[Bonnewagon]

From memory: 2 large red are 12 hot for the car, w/fusible links, go on the battery cable stud. Distributor gets a "pink" wire, may look orange or it was changed. Turn on the ignition and see if it's hot. Small brown should be alternator field (alt#1, Red is alt #2). Small green is temp sender. Small tan is oil pressure sender. Large purple is key switch to starter "S" terminal. Brown w/white stripe you got me there. Ooops, wait, brown/white is distributor to tach filter on 81' Chevy "A" series, may be same .

 

[81GrandPrix383]

Hey Bonnewagon,

Thanks. I found some information after I posted with the large purple and large reds. I have the battery and starter hooked up.
The Orange is for the distributor for sure because it has the correct connector on it.
The previous owner also spliced into that wire and has another wire coming off of it. Any idea what he may have had that for?

Correct me if I'm wrong.
I have an aftermarket tach to mount and a red wire going through my firewall with the correct clip to hook to the distributor. I can leave off the Brown/white stripe.
I have a single wire alternator so I only have a wire running to the battery. The small brown isn't needed then either.
I after aftermarket oil pressure and water temp gauges. Water temp has a sensor in the driver's head and it's own wire running to the gauge so the green isn't needed.
Finally my oil pressure gauge is mechanical so I have a tube running through the fire wall which I still need to plumb into the back of the block above where it meets the intake manifold. This means I don't need the tan.

Final question for now. What do I hook the electric choke to?
I heard oil temp switch or something. I'm going to need more info on this than just the colour of the wire. LOL. Thanks.

 

[Bonnewagon]

Sounds like you're good to go. I spliced into the pink wire too, but for an MSD red wire so I'd have a backup in place. Otherwise it's not a good idea to run anything but the distributor off that wire. As for the single wire alt, that brown wire is for the "GEN" light on the dash. I'm not sure what you'd use instead. Yes the electric choke runs off the oil pressure switch, look for a brown wire that is hot in "RUN", that goes to the oil switch but which can go right to the choke. It just has to be "HOT" in "RUN". The connector at the oil switch will have a brown,tan, and blue wire, blue goes to the choke.The oil switch basically turns the choke heater on as soon as oil pressure builds up.

 

[81GrandPrix383]

Thanks for the help again.

Is it better to use an oil switch rather than run directly to the choke?

I also have a volts gauge. I guess I need to figure out which wire goes to it....and what to attach it to under the hood.

I can't figure out how to hook the oil tube to the block for the oil pressure gauge.

I don't know how to get that coolant temp sensor to fit in the head properly.

I decided to call it a day.
I was filling my coolant and when I realized the temp sensor in the head didn't have the hole blocked. About 1/3 of a jug of coolant had poured onto the floor in the garage.

I really would like this car to start this year. LOL. I have about 10 grand into it.

Thanks for the help.

 

[Bonnewagon]

Sometimes you need to know when to walk away and grab a beer. The oil switch is so if the key is left in the "ON" position, without the motor running, the choke coil doesn't burn up or drain the battery. There should be a fitting or plug near the oil filter or at the top of the rear of the block that can be used for the oil gauge. The temp sensor comes in different sizes, or an adapter can be used. You'll get it going.

 

[81GrandPrix383]

You read my mind friend.
Took a break and cut the grass. Now I'm having a beer.

I have the hole at the top of the rear of the block that I plan to use but I can't get the right fittings to go from hose to block.
I know that port in the block is 1/8" pipe thread and have a fitting in there. I'm not sure what the size of the thread on the collar is that is on the metal tube that goes to the gauge.

The oil switch sounds like the way to go. So many to chose from though, how do I know which one to buy?

My coolant temp sensor made me laugh. i pushed the sensor in the hole, then put the threaded insert in to hold it in place. The part I didn't notice is that nothing was stopping the sensor from going right in. I can't believe I didn't notice and I need to see what it is supposed to look like to know what is missing. There is a flare at the base of the sensor that should fit snug in the hole and the threaded collar should hold it tightly in place stopping the coolant from running out. This is not what is happening. What a mess.