Starter wire routing - Chevy Nova Forum
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Old 31st-December-2009, 09:58 PM   #1
Tarantula
 
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Starter wire routing

My Nova's Starter wiring is all charred up. I bought it like this and soon will be tacking all the wire issues.
So I would like to know how is the wire for the starter/solenoid is routed. Also how is the alternator wire routed. I know one goes to the battery and one goes to the firewall, but not how its supposed to be routed.
I currently have exhaust headers.
Maybe pictures?
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Old 1st-January-2010, 02:56 PM   #2
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You might want to get some wiring from a donor vehicle. If you are lucky enough to get one off of the same year Nova (and possibly from a similiar make like the Ventura, Omega, Apollo) you might save yourself time doing splices in the wiring.

Basically there is a main feed off of the starter that goes up behind the passenger cylinder head and "T"'s off close to the distributor with one part going to the output post of the starter and then the other part continues on over to by the brake booster. 74's differ a little bit compared to the other cars as these have an interlock relay on the driver's side firewall in the engine compartment.
On the starter there is also a smaller wire attached to the S terminal and this wire is run next to the main feed wire off of the starter and it to goes over the the brake booster area. This wire only has voltage when the key is in the start position.
There should also be another wire connected to the starter's "I" terminal and this gets routed up with the main feed wire and solenoid wire to the coils positive post. This terminal on the starter will output 12 volts to give the coil full voltage to start the engine and then when the key is released back to the run position the coil gets a lower voltage signal through a wire that goes to the bulkhead connector by the master cylinder.

If you get a harness off of a donor vehicle it should have fusible links in place and protect the wiring. If you run your own wires then you need to add these protections.

As far as routing, keep it away from hot surfaces like the exhaust manifolds, headers, and exhaust pipes.

I would also get a wiring diagram to help with correcting your problems.

Jim
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Old 3rd-January-2010, 06:56 PM   #3
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Ok let me Explain how mine is routed.
On the Solenoid of the starter there are three posts. The large one gets a wire connected straight to the battery. Than theres another wire connected to the same large post and gets a T'd wire. Its red and thick (around 10Ga). This T'ed wire goes from a A thing that is similar to a junction box on the firewall to the T. Than from the T one goes to the Solenoid's large post (the same one that has the large wire connected straight to the battery) and the other goes to the Alternator rear post.

For the two small posts..
One post has a brown wire. That one gets connected straight to the bulk head on the firewall. The other small post has a blue wire. And that one gets connected straight to the bulk head as well.

There is no red power wire connected to my distributor. Other colors and they all come from the bulk head.
The bulk head is under the Brakes Master Cylinder (no brake booster) The junction thing is up above the Master cylinder. I also show a pic of my Distributor in case the way you state is not how my particular setup is routed.

One more thing. In order for the starter to work I have to connect a wire from the battery to the rear post on the alternator. This sends power to the bulkhead therefore making the car start.




Last edited by Tarantula; 3rd-January-2010 at 07:02 PM.
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Old 3rd-January-2010, 07:51 PM   #4
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This is out of the 1974 Chevrolet Service Manual:

On the starter solenoid you will have (or should have) the following wires:
A 2 gauge wire from the big stud on the starter solenoid to the battery positive post.
On this same stud you should have another wire with a fusible link (the manual shows it as a 14 gauge red hw) on the end that attaches to a red 10 gauge wire. This wire goes up behind the motor and over to the junction block on the firewall. Looking at the diagram it shows somewhere on this same wire another 10 gauge is spliced into it and routed to the output post of the alternator.
Off of the "S" terminal on the starter solenoid (the solenoid activation stud) you should have a 12 gauge purple attached to it and this wire goes between this "S" terminal and to a spot in the bulkhead connector. When testing this wire it will show 12 volts only when the key is in the crank position and be dead at any other ignition key position.
Now on the starter solenoid you are left with one stud and this may be marked with an "I" or from the manual is is labeled "R". Since the 74 was designed for a points style ignition and your picture shows an HEI installed this may or may not be used in your situation. This "I" or "R" stud on the starter solenoid outputs 12 volts when the starter is cranking. This is to send a full 12 volts to the ignition coil to fire the engine while it is being cranked over to fire up the ignition. Since this terminal goes dead when the key is released back to the run position GM ran a second wire off of the ignitions coil positive post and this wire has a resistance built into it to drop the battery voltage down and the wire then continues over to a spot on the bulkhead connector. The variable here with the picture showing an HEI, is how did someone wire up it's main power to make it work ?.

So, basically you should have a 2 gauge wire going to the starter, a 10 gauge red with a fusible link on the end going to the starter, a 12 gauge purple going to the starter, and also have a 20 gauge yellow. The yellow wire may not be needed depending on how someone wired in the HEI shown in your pictures.

There are other wires that go to things on the engine and these include a 20 gauge tan for the idle stop solenoid, a 20 gauge dark blue for the oil pressure switch, an 18 gauge dark green for the temperature switch, a 16 gauge red to the alternator, a 20 gauge brown to the alternator, a 20 gauge black-pnk print, and possible some others if the car has factory air conditioning.

If you look how the bulkhead connector is designed being a two piece plug, one half of the plug will have wires that go to nothing but the engine as the engine was wired prior to being installed into the car so the assembler on the line could plug it's half right into the bulkhead connector. The other half of the bulkhead connector will have the front end lighting and the wiper/washer wires in it.

Jim
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Old 3rd-January-2010, 08:39 PM   #5
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Thank you. That helps alot. Yes I did notice theres two plugs that make up the bulk head. Left side is engine and right side is lights etc.

I have an idea how the HEI is connected. There is a total mess. On the HEI there are three wires. Not sure of the colors as they are real dirty. These three wires goes straight from the bottom of the unit to the top which is where the little coil thing is located. Now on the top there is written Tach and Bat. There is a black wire that someone added (I think). Its on the Bat side and that has to be the power but without taking off all the black electrical tape, I cant see which wire its connected to from the factory to make it work. Most likely a switched positive. I will check to see.

The car is Non AC.
The HEI unit wire setup


The two wires T that has 2 different size wires as you stated is there.



And it appears theres a link and you can see the mess. You can see the HEI three wires on the bottom aluminum part. This goes to the top so I know these three are not part of the Car's wiring. And I can see what appears to be a fusible link near the connector for the solenoid.



Heres the alternator wires. Seems to match with the brown and red wires. So the out post on the Alt seems to be correct that it connects to the T'd wire.


Last edited by Tarantula; 3rd-January-2010 at 08:42 PM.
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Old 3rd-January-2010, 09:59 PM   #6
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What I would do is get the smaller starter wires routed under the header tubes and then bring them up on the backside of the cylinder head on that side. You might also look around and see if you can get the factory protection tube with an eared bracket welded onto it that GM used on the Nova's to help keep the wires in position and somewhat more protected. With the wires in this tube and routed under the headers you can take the headers on and off easily, have them more hidden, and be further away from the valve cover on that side.
For the main battery cable, bend the terminal end on a right angle and then have the cable going forward under the headers and broing it out in the front area of the motor. Some blocks also have small 1/4" threaded holes on the side of the block that were used to secure the spark plug metal shields and you could get some Adel clamps to secure the battery cable down better.

Even though the HEI has a terminal labeled BAT, you need to have this terminal showing a full 12 volts when the key is in the crank AND run ignition key positions and dead on any other ignition key position.

I would also either get a donor plug for the alternator or get the repair end from an auto parts store so no one can accidentally get the two wires inserted backwards.

If the wire with the "T" splice is solid and you are going to reuse it, put a layer or two of shrink tubing over it and get away from any electrical tape covering.

Jim
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Old 4th-January-2010, 12:50 AM   #7
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Custom Jim you are Awesome!!! Thank you! You have answered all my doubts perfectly!
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Old 4th-January-2010, 10:00 PM   #8
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No problem. I've seen my share of things through the years. The bad thing is you never know what others have done before you.

Jim
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Old 4th-January-2010, 11:31 PM   #9
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I would replace the fried wires going to the starter with GXL wire. It will hold up to the heat much better. I would avoid the general purpose wire. You could also wrap them in PET wire loom as it is rated to 125C as well. Your headers are close to the starter so you will have a hard time with wiring in that area.

I've had good luck with TXL and GXL wiring close to the headers that has melted the PVC loom that it was in but the wiring was ok. Nothing will hold up to laying on the headers though. You can lay the GXL wire on the engine without damaging it. The PET loom is an added layer of protection.
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Old 26th-December-2011, 09:55 AM   #10
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Quote:
Originally Posted by Custom Jim View Post
This is out of the 1974 Chevrolet Service Manual:

On the starter solenoid you will have (or should have) the following wires:
A 2 gauge wire from the big stud on the starter solenoid to the battery positive post.
On this same stud you should have another wire with a fusible link (the manual shows it as a 14 gauge red hw) on the end that attaches to a red 10 gauge wire. This wire goes up behind the motor and over to the junction block on the firewall. Looking at the diagram it shows somewhere on this same wire another 10 gauge is spliced into it and routed to the output post of the alternator.
Off of the "S" terminal on the starter solenoid (the solenoid activation stud) you should have a 12 gauge purple attached to it and this wire goes between this "S" terminal and to a spot in the bulkhead connector. When testing this wire it will show 12 volts only when the key is in the crank position and be dead at any other ignition key position.
Now on the starter solenoid you are left with one stud and this may be marked with an "I" or from the manual is is labeled "R". Since the 74 was designed for a points style ignition and your picture shows an HEI installed this may or may not be used in your situation. This "I" or "R" stud on the starter solenoid outputs 12 volts when the starter is cranking. This is to send a full 12 volts to the ignition coil to fire the engine while it is being cranked over to fire up the ignition. Since this terminal goes dead when the key is released back to the run position GM ran a second wire off of the ignitions coil positive post and this wire has a resistance built into it to drop the battery voltage down and the wire then continues over to a spot on the bulkhead connector. The variable here with the picture showing an HEI, is how did someone wire up it's main power to make it work ?.

So, basically you should have a 2 gauge wire going to the starter, a 10 gauge red with a fusible link on the end going to the starter, a 12 gauge purple going to the starter, and also have a 20 gauge yellow. The yellow wire may not be needed depending on how someone wired in the HEI shown in your pictures.

There are other wires that go to things on the engine and these include a 20 gauge tan for the idle stop solenoid, a 20 gauge dark blue for the oil pressure switch, an 18 gauge dark green for the temperature switch, a 16 gauge red to the alternator, a 20 gauge brown to the alternator, a 20 gauge black-pnk print, and possible some others if the car has factory air conditioning.

If you look how the bulkhead connector is designed being a two piece plug, one half of the plug will have wires that go to nothing but the engine as the engine was wired prior to being installed into the car so the assembler on the line could plug it's half right into the bulkhead connector. The other half of the bulkhead connector will have the front end lighting and the wiper/washer wires in it.

Jim

Old thread, but a lot of really good information here.
Now I understand how all those wires work from the starter to the coil and what I need to do to switch to the HEI.
Big thanks Jim!
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