HEI Distributor Wiring

[Swac]

I have a 1967 Chevy C10 Step-side and I have switched to a HEI distributor and I am trying to run a 12 g wire from the IGN fuse box through the firewall to the HEI distributor to the positive side. My question is how? Pictures would be greatly appreciated on how to do this and I welcome all suggestions. I am not understanding how to run the wire to the HEI dizzy (i.e., do I unplug the wire that is normally plugged into the port and just run the single 12g wire and put some type of connector into that port?) Again any information would be greatly appreciated and thank you in advance! Lastly, any info and pictures on how to wire the 12g to the fuse box would be a great help as well and pictures would be wonderful. Thx again!

[LockDoc]

Originally Posted by Swac

I have a 1967 Chevy C10 Step-side and I have switched to a HEI distributor and I am trying to run a 12 g wire from the IGN fuse box through the firewall to the HEI distributor to the positive side. My question is how? Pictures would be greatly appreciated on how to do this and I welcome all suggestions. I am not understanding how to run the wire to the HEI dizzy (i.e., do I unplug the wire that is normally plugged into the port and just run the single 12g wire and put some type of connector into that port?) Again any information would be greatly appreciated and thank you in advance! Lastly, any info and pictures on how to wire the 12g to the fuse box would be a great help as well and pictures would be wonderful. Thx again!

There is a terminal in the fuse box marked "IGN UNFUSED" you will need a wire with a female spade terminal on the end of it to plug into that. Then just run the wire through the firewall and figure out the length you will need to to connect it to the "BATT" terminal on the HEI. You will have to install another female spade connector on the wire to connect to the "BATT" terminal.

LockDoc

[Swac]

Will one female spade connector plugged into the IGN Unfused work or does both need to be plugged into it?

[LockDoc]

Originally Posted by Swac

Will one female spade connector plugged into the IGN Unfused work or does both need to be plugged into it?

Just one.

LockDoc

[Swac]

I have included two pictures of my actual Fuse Box and the HEI distributor.

[LockDoc]

Originally Posted by Swac

I have included two pictures of my actual Fuse Box and the HEI distributor.

I would say that you need to replace your fuse box, it looks pretty rusty.

Unless you have a tachometer you should only have one wire going to your HEI distributor, and it should be connected to the "Batt" terminal. (the "BATT" & "TACH" terminals should be marked on the distributor cap).....

LockDoc

[Swac]

Originally Posted by LockDoc

I would say that you need to replace your fuse box, it looks pretty rusty.

Unless you have a tachometer you should only have one wire going to your HEI distributor, and it should be connected to the "Batt" terminal. (the "BATT" & "TACH" terminals should be marked on the distributor cap).....

LockDoc

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[Swac]

Originally Posted by LockDoc

I would say that you need to replace your fuse box, it looks pretty rusty.

Unless you have a tachometer you should only have one wire going to your HEI distributor, and it should be connected to the "Batt" terminal. (the "BATT" & "TACH" terminals should be marked on the distributor cap).....

LockDoc

Thank you for the valuable input and I ordered one tonight and again thanx!
Posted via Mobile Device

[LockDoc]

Originally Posted by Swac

Thank you for the valuable input and I ordered one tonight and again thanx!
Posted via Mobile Device

No problem. Let us know how you get along with it....

LockDoc

[MARKDTN]

I would go about this differently. I would replace the wire that went to the coil in the engine harness where it plugs into the fuse block. All the resistor wire is on the engine side. Crimp a type 56 connector onto your new HEI wire and swap it in the block. You can get type 56 connectors at NAPA, CarQuest, GM Dealer, Ebay, etc. Just be sure to disconnect the yellow wire on the starter.

[Swac]

Thank You LOCDoc

[dmjlambert]

You are probably getting 12V during start and reduced voltage when running, which is for a points type distributor. I suggest look at this
https://67-72chevytrucks.com/vboard/...d.php?t=708975

[steviemack]

Thank you. This is exactly what I was looking for.

[Andy4639]

Simplest way to do this is pull wire that was on the original distributor out of the wrap down to the fuse block. Leave yourself enough wire to splice onto it. Then run new wire back to HEI.

The original wire was a resistor wire but it wasn't the whole length of the wire. I have done this to several trucks and cars with no problems.
The picture is the wire connector on back of the fuse block. Yes I know it needs to be better but it just hasn't been done yet.
The original wire has the cloth jacketing on it so it's easy to follow back to the fuse block.

[steviemack]

Originally Posted by Andy4639

Simplest way to do this is pull wire that was on the original distributor out of the wrap down to the fuse block. Leave yourself enough wire to splice onto it. Then run new wire back to HEI.

The original wire was a resistor wire but it wasn't the whole length of the wire. I have done this to several trucks and cars with no problems.
The picture is the wire connector on back of the fuse block. Yes I know it needs to be better but it just hasn't been done yet.
The original wire has the cloth jacketing on it so it's easy to follow back to the fuse block.

That's alot of wrap between there and the fuse block. Sorry but I don't know what a resistor wire is other than it doesn't carry 12V? You are indicating that since the original wire was a resistor but not the entire length that it would be ok to split into in prior to the the resistor portion closest to the fuse block? How do you tell where the resistor ends?

I am looking at my fuse block on the drivers side firewall next to the brake booster and I am not seeing a wire with a cloth jacketing.

The truck runs pretty darn good with this configuration but now I am curious to know how much better it would run if not getting a full 12V at the distributor BATT post. Now my wheels are spinning about spark plug gap and wire gauge. The only issue I am having is just a very slight hesitation upon acceleration off the light but I was told that the 600 CFM carb as a bit much for the 307.

I have a multimeter but not sure how to test for 12V on the wire currently being used.

[Steeveedee]

Originally Posted by steviemack

That's alot of wrap between there and the fuse block. Sorry but I don't know what a resistor wire is other than it doesn't carry 12V? You are indicating that since the original wire was a resistor but not the entire length that it would be ok to split into in prior to the the resistor portion closest to the fuse block? How do you tell where the resistor ends?

I am looking at my fuse block on the drivers side firewall next to the brake booster and I am not seeing a wire with a cloth jacketing.

The truck runs pretty darn good with this configuration but now I am curious to know how much better it would run if not getting a full 12V at the distributor BATT post. Now my wheels are spinning about spark plug gap and wire gauge. The only issue I am having is just a very slight hesitation upon acceleration off the light but I was told that the 600 CFM carb as a bit much for the 307.

I have a multimeter but not sure how to test for 12V on the wire currently being used.

The resistor wire insulation is white, with orange and purple stripes (seriously). That resistor wire is braided, and it is not copper. It's Nichrome, I think. It lays back and forth a couple or three times in the harness to get the voltage drop for a Kettering ignition. It tees into the yellow wire on the "R" terminal on the starter solenoid.

To check, turn the key on and attach the ground probe to a good ground. The coil power wire (yellow) (disconnected from the coil) should read around 7V-9V, somewhere in that area. It will, in any event be much less than battery voltage, if it has the resistor wire intact.

Here's a wiring diagram to help-

[slikside]

Originally Posted by steviemack

That's alot of wrap between there and the fuse block. Sorry but I don't know what a resistor wire is other than it doesn't carry 12V? You are indicating that since the original wire was a resistor but not the entire length that it would be ok to split into in prior to the the resistor portion closest to the fuse block? How do you tell where the resistor ends?

I am looking at my fuse block on the drivers side firewall next to the brake booster and I am not seeing a wire with a cloth jacketing.

The truck runs pretty darn good with this configuration but now I am curious to know how much better it would run if not getting a full 12V at the distributor BATT post. Now my wheels are spinning about spark plug gap and wire gauge. The only issue I am having is just a very slight hesitation upon acceleration off the light but I was told that the 600 CFM carb as a bit much for the 307.

I have a multimeter but not sure how to test for 12V on the wire currently being used.

The real reason for getting the full 12v to the HEI, is so the HEI module doesn’t fail due to improper voltage, and leave you “high and dry”. It may run great, but over time, without the right voltage the module will fail. Lots of threads on here about this issue...

[steviemack]

So when I upgraded the manifold and the stock 2 barrell caburetor to a 4 barrell, there was a two pronged electrical connector attached to the 2 barrell carb and a hot wire connected to the choke. I left the two pronged connector disconnected and connected the hot wire to the 4 barrell choke.

The two pronged connector also had a hot side putting out 12V only with key on. Today I ran a wire from the hot side of the two pronged connector to my 4 barrell choke and connected the original hot wire connected to the carburetors choke to HEI BATT terminal. This wire was also putting out 12V only with key on and appears to go directly to the fuse box inside the cab. Both wires are part of the original wiring.

Any thoughts on this configuration?

[Steeveedee]

What gauge is the wire? The HEI likes as close to battery voltage as you can get it, that's why it's a 12 ga (?) wire. The wire you have may have too much voltage drop when the engine is running. You could check that easily enough, just check with the voltmeter at the connector on the distributor. Is your meter high impedance? It should say on it. I'd recommend a high impedance meter so that not too much power is taken off the wire when you sample it, which could make the voltage reading lower.

[steviemack]

Originally Posted by Steeveedee

What gauge is the wire? The HEI likes as close to battery voltage as you can get it, that's why it's a 12 ga (?) wire. The wire you have may have too much voltage drop when the engine is running. You could check that easily enough, just check with the voltmeter at the connector on the distributor. Is your meter high impedance? It should say on it. I'd recommend a high impedance meter so that not too much power is taken off the wire when you sample it, which could make the voltage reading lower.

I am pretty sure it is 12 gauge wire. It's almost as big around as a pencil. I will double check the voltage when running. Maybe it's my imagination but it seems to be running even better now.

[68 P.O.S.]

Not mention coil layer shorting which takes modules out in a split second

[Luvlegs]

Tried to attach link for how I cleaned up my fuse block. ..https://67-72chevytrucks.com/vboard/...ght=Fuse+block

[Luvlegs]

Tried to attach a link to how I cleaned up my fuse block - it's been awhile... https://67-72chevytrucks.com/vboard/...ght=Fuse+block

[A1971Blazer]

The wiring on mine was pretty hacked...I got a new engine harness from AAW that was already set up for HEI
Plug and play

[bry593]

Basically, you want to mimic GM 1975 and later wiring. It is 12 AWG, Pink, Cross-Linked Thermoplastic wire (GXL). You only need four feet or so. You will also need an Aptiv (used to be Packard 56) female terminal at the HEI and a male terminal at the firewall junction block.

This is the only 100% proper way to do this (just like GM did it).

The old stainless steel resistance wire should be completely removed from the harness, including the old yellow bypass wire from the starter to the coil. The harness should be re-wrapped in 1.25" wide, non-adhesive, vinyl black tape.

I've done a bunch of 'em.

And, as A1971Blazer says, American Auto Wire is your best source for a replacement engine harness. And it is no problem for them to make it with HEI connectors and wire type. AAW is the best and just an engine harness will not break the bank.