ignition issue some gremlin...

[gmc684x4]

Loose taped positive wires are a potential electrical fire in the making

One question did you run your new wire through a grommet ?
Running wires through sheet metal will cut the wire not a matter of if but when

[dmjlambert]

Originally Posted by scottmitchellrose

You have ALL helped out a lot- thank you! Yesterday I put a 12 gauge wire from the fuse box ignition straight to the HEI distributor and that worked. However, the battery terminals became VERY hot... I must have a short somewhere. I recently grounded the head the the frame right by where the power steering pump sites. I should probably ground the valve cover bolt to the cab, too. I taped off the old 'resistance' wire from the points distributor, so that shouldn't be it... but who knows. 50 year old wiring... One day I'll figure out how to go straight from the ignition to the HEI instead of the fuse box.

Can you please post a picture of the battery terminals that are getting very hot?

[scottmitchellrose]

first batch...

[scottmitchellrose]

[dmjlambert]

Are these terminals the ones getting hot?

[firedemon]

that looks like a lot of creative wiring there . looks like theres no grommet on the hole that your new yellow comes through . that being unfused will burn real bad please find a grommet at very least a piece of fuel line over the wire temporarily .

[scottmitchellrose]

yes, those are the terminals. I will put a grommet in as soon as I get her running right. wired to add the 2 electric fans. long wires, lotta mess, I know. Once everything is 'right' I can clean that up/ shorten wires/ wrap everything nice and tight.

[dmjlambert]

I have some recommendations.

1. Those type of terminals are called repair terminals. They are suitable for very short time use (1 month maybe). They are subject to high resistance caused by corrosion. They are really just bad. I suggest get a battery cable with moulded terminal ends. Here is a post with the correct positive battery cable part number. ACDelco ACD# 4BC53X GM# 88860050
http://67-72chevytrucks.com/vboard/s...d.php?t=734496

For the negative battery cable you can get a 25 to 30 inch heaviest duty battery cable from your car parts store, or Chevy dealer if you're able to get them to look up the right cable for an old truck.

2. Turn the battery around so the positive post is closest to the passenger side fender.

3. The positive battery cable has only 2 wires coming from it, the big fat wire that goes to the starter, and the 12 gauge smaller wire. Attach a 6 to 9 inch piece of 16 gauge fusible link wire to that 12 gauge smaller wire, and attach the other end of that fusible link to a screw terminal on the fender. Fusible link is a special wire available in short sections at the auto parts stores. It is usually grey in color and it has an insulating jacket that does not catch on fire when it overloads. The wire inside is designed to burn up first when you have a short, and save the rest of your wiring harness. It looks like your screw terminal junction block may be missing. You can get new ones. This is what they look like. https://www.ebay.com/itm/133445485058


From that junction block, connect the main 12 gauge red wire that runs in the wire bundle across the top of the radiator over to the wires near the driver side headlight. If your 12 gauge red wire has been chopped up by modifications done in the past, you can lengthen it slightly with some additional 12 gauge red wire available at car parts stores, so it goes to the junction block.

4. Re-do any crimp butt connectors that attach one wire to another. I think they will cause problems. Instead, twist wires together and solder them and cover the joint with heat shrink tubing. Or better yet, replace whole wire lengths so you don't have splices in the middle of wires. When you do have splices, make sure they are good ones. If you need any terminal ends, these trucks use Packard 56 terminals and connectors for most of the connections. You can buy those online. You can also buy automotive wiring in all sorts of colors and sizes online.

5. The electric system you have and that alternator probably won't handle the load of electric fans. I recommend, if you can, remove the electric fans and put a mechanical fan back onto the water pump and put a shroud on the radiator. It is a more efficient setup and won't require electrical upgrades and customizations, new alternator, etc.

6. The factory makes things neat and kept the wires in bundles using non-adhesive vinyl tape. You can unwrap the existing harness and add wires for things such as electric choke, and then re-wrap it, or use fresh non-adhesive vinyl tape.

[dmjlambert]

Here is where the junction block goes

[scottmitchellrose]

OK, fortunately for me a friend from Cheraw (Dana) came up a few weeks ago and helped A LOT! He was able to put a new wire from the fuse box to the HEI distributor. I am still having issues, though. some of the cylinders are not firing. I only tested the front 4 (2 on either side) and only 1 of those was firing (#3 if I remember). I've replaced the distributor, and replaced the plugs/ wires as well (2 new sets, 2 new distributors chasing this...). I've checked tdc a few times. I don't have anything running from the "R" on the starter solenoid. Could that be the issue?

[dmjlambert]

No, for an HEI distributor you don't need anything connected to R. The R terminal is only used to send full 12V and bypass resistor wire to coil of a points distributor during start. So, it's just not needed for HEI.
Did you use a spark tester at your spark plug wires and don't see a spark at some of them? Is that how you tested? Are you using a new rotor and cap on the distributors?

[scottmitchellrose]

Yes, sir. tried 2 new distributors and 2 new sets of wires. I'm hearing that the cheapo distributors are junk- and that's my problem. just ordered an msd for 180 bucks on amazon- let's see if that's it....

[RichardJ]

>> long wires, lotta mess, I know. Once everything is 'right' I can clean that up/ shorten wires/ wrap everything<<

That's about as ass-backwards as it gets. Fix all that garbage wiring laying all over the place. Get the plug wires shortened and held organized with decent wire holders. Plug wires should not be taped in bundles and make sure #5 & #7 wires don't run parallel next to each other.

A $180 HEI isn't going to solve your problems, what ever they actually are.
If the cheapest, oldest, worn out HEI is supplying secondary voltage to a couple of the plugs and the dist cap is good, then the problem lays either in that wiring mess or your testing procedure.

[scottmitchellrose]

ughh.... well... i'll try it first when it arrives, and then if it fails... perhaps build a bon fire... 2 years of this!

[mr48chev]

I'm with Lockdoc on that one. I used the ign unfused on my 71 without any issues. I just taped the end of the original point system wire, rolled the wire up neatly and taped it up and tucked it away. I had to replace the wire from the fuse block with a longer one when I put the 500 Cad in it.

The main thing is use a high quality female slide wire end that fits tight on the spade. Use a designed for HEI connector on the distributor end as female slides tend to come loose going down the road and on mine it was usually at 03:30 am in a rain storm on the way to work.

[scottmitchellrose]

Dana drove up and helped me out. All set- thanks to EVERYONE.

as it turned out I had not one but 2 brand new distributors out of the box that were absolute CRAP from China. also, he cleaned up my wiring.

Scott

[LockDoc]

Originally Posted by scottmitchellrose

Dana drove up and helped me out. All set- thanks to EVERYONE.

as it turned out I had not one but 2 brand new distributors out of the box that were absolute CRAP from China. also, he cleaned up my wiring.

Scott

Sounds good. Glad you got it figured out.

LockDoc

[davischevy]

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