Firewall routing questions and points distributor wiring for the purests 71-C10 A/C

[71CHEVYSHORTBED402]

This was converted to HEI, and the guy ran the wire through speedometer cable hole. Same thing for a kill switch (never mind two 10 ga. wires for a CB). Won't fly with the rebuild. I'd like this truck returned to its factory glory less the HEI, and would appreciate any input on.......

A. Where/how do you recommend routing the HEI wire? I believe they should be 10 gauge wire. Is there another spot for say a 12 gauge wire (e.g., kill switch)? I guess I'm looking for "spares" through existing grommets, which may not be an option, but probably is because.......

B. This truck doesn't have a tach or vacuum gauge, and I'm not likely to install either. Where were these routed through the cab?

C. How were the original distributors wired?....the power, not firing order. I imagine they ran to the ignition right? If it came through the cab then where?

Descriptions work, but pics appreciated as well.

Thank you

[Gromit]

My two cents is to bite the bullet and spring for the American Autowire Factory Fit engine wiring harness.

You can specify your exact features (mostly motor, trans, distributor A/C or Non) and it comes with all new grommets and channels and hold-downs and resistor wires all in the right location.

I did restore my dash and rear light harnesses at much effort but the engine harness was so cooked and spliced over the years - believe me it is well worth the $109 You can easily spend a couple days trying to figure out and restore a dusted harness..

http://www.americanautowire.com/shop...harness-137291

[Ironangel]

This might help http://farm4.static.flickr.com/3645/...c2a8064d_o.jpg
The HEI can be wired from one of the ignition unfused terminals located on the fuse block. Heres a pic of the fuse block with highlighted markings,
I ran my HEI, Tach, and rev limiter wiring through the grommet used for the oil pressure line, it has room for added wiring.
Most of the underhood wiring comes from a terminal block located near the master cylinder hydrovac canister below the speedometer cable outlet.
Sorry for the big pics, the factory distributors had a resister wire used to keep from burning up the points, you cannot use that wire for HEI distributors because the resister wire limits voltage. You must run a dedicated 10 or 12 gauge wire that supply's a full 12 volts to the HEI. The unfused terminals on the fuse block do this as well as being keyed through the ignition switch.

[71CHEVYSHORTBED402]

Originally Posted by Gromit

My two cents is to bite the bullet and spring for the American Autowire Factory Fit engine wiring harness.

You can specify your exact features (mostly motor, trans, distributor A/C or Non) and it comes with all new grommets and channels and hold-downs and resistor wires all in the right location.

I did restore my dash and rear light harnesses at much effort but the engine harness was so cooked and spliced over the years - believe me it is well worth the $109 You can easily spend a couple days trying to figure out and restore a dusted harness..

http://www.americanautowire.com/shop...harness-137291

Thanks for that. I hear the same applies to M&H wiring as well. I am planning to rewire all. Hold downs as in wire harness retainers?

[Ironangel]

Here's another helpful link, http://67-72chevytrucks.com/vboard/s...d.php?t=454737

[randy500]

Or you could use the wire location for the coil on the factory wiring harness and not worry about getting through the firewall...replace the resistance wire with regular wire...why doesn't anybody think of the easiest method?

Find coil wire in engine harness, squeeze terminal to release(blade side), get new terminal or solder new wire to old terminal. No need to go through the firewall with some hokey method like through the speedo cable grommet. You will thank yourself if you ever have to tear down the truck or troubleshoot it....so will the next guy.

Don't forget to unfasten and tape up yellow wire on starter relay terminal as it leads up to a splice in the original coil wire.

[71CHEVYSHORTBED402]

Thanks for the responses. I have to pull the wires from the cab yet. I'll wait for that to soak this in, so I can speak somewhat intelligently with any further questions. I'm getting a complete wiring kit, which I believe includes new plugs (e.g., firewall plug). From what I understand there's a provision for HEI.

This no longer has a points distributor, so there's not a splice to the coil. The only yellow wire was butt connected to a redish wire from the RH (truck side) portion of the fire wall plug. The yellow was to the starter solenoid. I believe the location of the red wire on the plug is what the book shows as orange/purple. No sign of a orange/purple wire.

Difficult to judge what's right when tampered. Thank you.