67 Firebird Ing wire question. Installing HEI
 

Hi group. I want to install an hei distributor on my 1967 Firebird with 326.
I'd like to tie a wire for the hei (for full time 12v) into the origination point of the resistor wire (pink/black(?)) right at its source so I can leave that original wire in tact. My question is: does that resistor segment of the stock ignition wire originate at the key switch, or the fuse block, or the wire connector cluster at the firewall below the master cyl?
Thank you

That will not work because that wire is not powered when the motor is just being cranked over, only in the run position does that wire stay powered.

If the 67's have essentially the same wiring as the 69's, the resister wire will be in the fuse block. The black wire with pink stripe that goes from the firewall bulkhead connector, to the coil is not the resister wire, but it's also not meant to carry the amount of current that the HEI needs.

if you're concerned about being able to put the car back to stock easily without a bunch of mess, I would wire the HEI from a relay. 10gauge wire from the battery to the relay and from the relay to the HEI. Trigger the relay with the current coil wire. This will allow you to run the HEI without cutting up the harness or re-pinning the bulkhead for a larger gauge wire. It also give you full battery voltage at the HEI, which it will want.

The drawback to this system is that if you've converted to an internally regulated alternator, or a 1 wire alternator, you'll get feedback through the "Gen" dummy light and the relay won't close on key off. You either have to remove the green wire from the engine harness to the alternator, or you need to diode protect that circuit so it doesn't feed back.

Thank you guys. And thank you Geoff.
Do you suppose this relay will work?

https://www.napaonline.com/en/p/TWRR...g_dcoe_google&

Yes, that's the type I used when I converted my 68. Usually rated at 40 amps. I don't know how many amps an HEI draws.

IGN-2/crank, should (I'm thinking) come up from the starter solenoid R terminal.

If two wires are hooked to coil (+) now.. both will be needed to trip a relay for crank and run.

Clay

What I did on my 65 Tempest is pony up and bought an engine harness from our sponsor that was configured for HEI. Mine also was configured for an SI alternator but don't see that option for a 67 Firebird. Its not cheap but you don't splice anything on the original harness if you want to go back to points at sometime in the future.

Question:
The wire from the ignition switch for 'run' (the resistor wire to the coil)
Is this wire energized (1967 Firebird) during the cranking selection of the ignition switch? Or is the wire from starter solenoid 'R' the sole power to the coil during cranking?

I took the easy route. I hid my original wire within the loom and ran a separate wire from the fuse box ignition terminal to the hei. If I want to go back, it's already there ready to hook up the original wire.

On my 68 I spiced 10ga wire onto the run wire about 2" behind the ignition switch then ran it thru the firewall to the distributor to give me the correct voltage needed for the HEI conversion. The conversion was already done when I got the car but was using the stock coil wire. At some point I'll pull the engine to freshen it up and really tidy up the engine compartment.

OK, so I'm using the stock coil wire right now (GM type aftermarket coil in cap). I checked it and it shows full 12 volts. The car runs fine. Am I asking for problems?

Did you check it with the engine running?

No, and the car is currently stored for the winter. I will check as soon as I fire it up in spring. What should I be concerned about since it seems to be working fine?

The HEI will be pulling little current with the switch on and the engine not running. In that case you may read as high as 12V at the HEI power connector, even if the supply is through a stock resistance wire. Once you get the engine running the voltage reading could drop off as the HEI's load increases. Enough to make the HEI malfunction? Not so far.

What you're describing is how I've done it for years and works just fine.

All of my factory point ignition cars (except the Nomad) only use a resistor wire from the junction block to the coil, that's it. There is no resistor wires from the ignition switch to the fuse box.

So what I do is remove that junction block outside on the firewall, pop out the resistor wire, I have those special spade terminals here for larger gauge wire, so I run a 10-12 gauge from that connection, and also crimp the resistor wire in with it, plug it all back in. I run the new wire in the harness following the resistor wire.

Now I have the option at the coil to hook up the resistor wire for points, or hook up the full 12 volt wire for an HEI or point conversion setup.

It's nice having it this way because it has saved me a couple times when I've switched the cars back to points. It was just a simple wire connection change at the coil and done. No extra stuff anywhere to wire up, and it looks stock when finished. It's also nice when running an MSD box that needs a 12 volt trigger wire with a points ignition. If the box ever fails I swap a couple wires and plug my resistor wire back onto the coil and I'm back on the road in a minute, and back to firing with points using the proper resistance.

In fact, when you order new engine harnesses from places like American Auto Wire for your classic car, they give you the option of doing exactly this and will incorporate this into their harness kits.

I prefer this method. The HEI is a sneaky sort of current hog and if you have the proper instrumentation you will observe a massive but imperceptibly short burst of current generated at each ignition pulse. It's one of those things where everything seems great and you just can't figure out why you seem to have a miss at full throttle high RPM runs.

Pontiac used a bridge right at the ignition switch to join Ign-1 and Ign-2 together for their optional electronic ignition in 1967. That bar isn't reproduced and it's just easier to come away from the switch a couple of inches and tie the two wires together and run a 10-ga wire out to the HEI unit. I originally put a switch in line between the two in case I went back to points, but in the 30 years after putting the switch in it has never been used.

I have always just run it this way.

Points cars that had resistance wire under the hood, used 14 awg wire from the ignition switch (IGN-1) to the firewall/bulkhead connector.

HEI cars used 14 awg wire from the ignition switch (IGN-1) to the firewall/bulkhead connector. They used 12 awg from the firewall to the BAT terminal on the HEI distributor cap. The 12 awg was used because of extra high under hood temperatures that early smog era engines had. When copper gets hot, current flow slows down. The bigger wire kept current flow equal to the 14 awg wire under the dash.

Early birds did use starter solenoid 'R' terminal for IGN-2/crank.

While GTO's and full size cars had IGN-2/crank coming from the ignition switch.

I for one don't like over complicating things. The old failure reduction quote comes to mind now.
" "Failure varies directly with how well you are able to reduce the factors that increase its risk." "

IMO I would use one terminal with two wires in it to power the HEI. One ran inside to IGN-1 and to by-pass the resistance wire. The other wire going to starter solenoid 'R' terminal.

Clay

As someone who did it on the exact same model I would offer two pieces of advice.

1. Just have a new engine side harness made by AAW. Its not that expensive for that harness, they will make it to fit your needs so no splicing. Old wiring is a killer on old cars so you kill two birds with one stone here.

2. Just dont do it. This is nothing to do with not liking HEIs, they work just fine. Its just that the first gen cars are deigned with a small cap in mind. You have very little room. I had one in for a couple years and eventually went to a small cap unit because of the space constraints. If you have the heater hose in the back of the head like normal, you are just left very very minimal room to put the distributor in and allow for timing adjustment without hitting that hose nipple. I have heard that on 68-69 cars you can turn the distributor around, but the hard linkage on 67s dont allow for that. So my advice would be to save the headache and buy something with a small cap.

Yup, before I went with the new Ames (M&H I believe) harness, this is what I was going to do. A small box to enclose an automotive quality 40A relay with a terminal strip to connect the original coil lead, tach lead, and the 12 AWG 12V power lead. The relay with cause no noticeable voltage drop across the resistance wire. This way you keep all the original wiring. I decide against this as I've read in other posts that the external regulator of the original alternator can potentially cause HEI failures. Not sure about that but as I needed to increase my alternator current capacity anyway, I went for the engine harness that is configured for HEI & the SI alternator. Its been a great set up.

Now, something else about the HEI, you may find issues with modern radios that have a USB interface for your phone, Ipod etc. I did, it took wiring separate grounds, power leads and a lot of ferrite beads on the USB radio cables to fix the problems.