Jump to content

HEI distributor conversion and wire identification.


The Archivist

Recommended Posts

Hi All!

Having finished a partial frame off for new body bushings (1970 Monte), new front end OEM style and engine bay painting were replacing the existing 454 with a new ZZ502 and a beefed up r4/700, The new ZZ502 deluxe crate option comes with a GM HEI distributor. The previous setup had an 6a MSD box ignition system and dist/coil. Some of the wires in the engine bay I need some help identifying and how to convert to the HEI system.  This is the first hurdle:

Note the pictures with the five wires, 12awg purple that did go to the starter, a white fabric cloth like style wire 16awg that had been crimp tied into the MSD box wiring, the remaining 16awg Orange (was cut no connection and taped off) and the purple/black 20awg wire with the black connector went nowhere as well and was also taped off and a 18awg purple/black wire that was also cut off and taped. 

The TCS relay we removed as it also had its wire harness going nowhere just hanging loose. Note: The loose brown wire on the firewall is the tach wire and 12 awg red went to the carb. 

 

Thanks for any input. 

IMG_20210304_123137.jpg

IMG_20210304_123319.jpg

IMG_20210307_122331.jpg

IMG_20210307_122407.jpg

IMG_20210307_122427.jpg

IMG_20210307_122444.jpg

IMG_20210307_122457.jpg

IMG_20210307_122537.jpg

Link to comment
Share on other sites

Part 2: Were also trying to understand what this one red connector went to (see pic) and why the voltage regulator (AC Delco box) had the large 4 wire connector removed. The car operated fine without these two plugs engaged.

IMG_20210307_122100.jpg

IMG_20210307_122122.jpg

Link to comment
Share on other sites

I may have an answer on a couple of the wires. Chevrolet ran two wires to the transmission, orange and purple. The orange wire was extra for a manual trans and was to be cut off and taped off. The black with blue stripe is for the TCS harness. There is also a short harness near the wiper motor that was for the idle stop solenoid. Must folks removed those solenoids. That's all I have for you and hope someone will confirm these for me. Good luck

Link to comment
Share on other sites

My guess on the voltage regulator is that at some point the alternator was replaced and the new one has an internal voltage regulator. The original voltage regulator was unplugged.

Link to comment
Share on other sites

Thank you guys this helps. So this just leaves the white nylon like cloth wire to identify which was tied into the MSD 6A box. The large purple we know goes to starter now. 

Im hoping this last odd white wire is the 12v that goes to the new HEI on the crate ZZ502. 

IMG_20210307_122444.jpg

IMG_20210307_122407.jpg

Link to comment
Share on other sites

Also these two wires brown and red brown (in the center) went to the tach and the red to the Holley carb. Im adding a connector the brown for the tach on HEI dist and I assume the red goes on the new Holley 870CFM in the crate engine. 

 

 

IMG_20210307_122331.thumb.jpg.fbba7a7d1887ad78adcf81570e07a270.jpg

Link to comment
Share on other sites

I don't know about the MSD setup, but have HEI in mine. My HEI requires only a hot wire from the ignition. It's sensitive though, and requires a full 12+ volt supply...I have my power routed through a relay for the power supply.

When I changed to a mini starter, I had to install a diode kit because the mini has no dedicated feed for ignition while cranking. The diode kit is just a length of wire from the starter that has a diode along its length. I got the diode kit from American auto wire. 

Link to comment
Share on other sites

  • 2 months later...

Hey Caulder, any updates on your progress ? I have the ZZ502 also, already had an HEI dizzy on the 454 from the PO. My buddy upgraded his 6AL to a 7 and offered me his 6. From what I've seen on the net you need a low resistance bushing, possibly a dizzy cap adapter, and a stand alone msd coil, also can't use solid core spark plug wires. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...