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Old 03-25-2003, 10:15 AM
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Post HEI wires getting hot!

I have a hei setup on my 383,71 elcamino.I have visually inspected wire harness(s). New engine harness, front headlamp harness is new, rear light harness is new (opg). There are two wires joined together at the hei unit one is from the starter (yellow) and the other is (pink) i assume the pink wire is from the ign, switch.After running for 5 min both wires are melting the insulation.

isnt there a seperate hook up for the ign switch and the other for the stater at the hei?

Heres the kicker the car has run fine for the past 3 months, with no changes to the wiring in any way.
Any thoughts, help !!!
any thoughts

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Old 03-25-2003, 11:28 AM
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Don't know what the individual wies do but I don't think it matters. From your description of the problem, you have an end device (HEI module? Coil?) that is failing and is shorting out. Engine will likely stop running soon when the device fails completely. You need to see someone wiht the new-fagled electronic doohickies to check it out.
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Old 03-25-2003, 06:56 PM
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Anyone out there please correct me if I am wrong, but the wiring of your HEI distributor appears to be incorrect. The positive side of the coil (BATT)should receive a full 12 volts at all times with no resistor. The only other wire you would have would be a Tach lead from the tach terminal on the coil.

The original ignition by-pass wire should be run to the 12 volt wire as well. If you don't, while in the crank mode you will have no elec to the ignition until you release your key back to the run mode.

You can go to <a href="http://www.madelectrical.com" target="_blank">www.madelectrical.com</a> for some good tech advice and HEI solutions as well.

Obviously you have too much resistance in the system or your wires would not be melting!

Good luck, I hope this helps.

[ March 25, 2003: Message edited by: Short Bed Shorty ]</p>
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Old 02-17-2006, 11:40 AM
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OK, the one wire from the solenoid is for starting the engine and is only activated from the battery when the solenoid is activated. It supplies starting full battery volts for both points and HEI ignition systems. On some later vehicles, this wire is movedd from the R term on the solenoid to the IGN 2 part of the ignition switch, same operation.

The "pink" wire is from the ignition switch, IGN on points models, IGN 1 on later ones. This wire provides running voltage to the ignition system and can be resisted for points systems, oir full volts for an HEI.

On most later GM vehicles with IGN 1 and IGN 2 at the ignition switch, these wires are NOT resisted, as they are for use with an HEI from the factory.

From the melting of the insulation, I suggest checkling for a short in those lines, or more likely, either an ignition coil at the very start of a layer short inside itself, or carbon bushing/rotor issue, like the rotor tracking voltage through it to the HEI mainshaft under it, overloading the coil, etc.

If the stock GM fuse box is in place, then I'd suggest pulling the wire connector(s) off it from the engine side of the firewall, and checking for corroded terminals/connects inside the junction. The connect should be retained with one centrally located screw. Clean and regrease the connector with di-electric grease if the connects are dirty. It doesn't take a whole tube of grease on the junction, just enough to keep the weather out of it, a little goes a long way.
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Old 02-17-2006, 12:29 PM
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Check the size of the wire,if the car originally had points it will only have 20 gauge wire,hei had 12 gauge.
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Old 02-17-2006, 03:36 PM
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Doc here,

Measure the coil, Get out your DVOM, set it for R X 1 ohms, calibrate it..
(Touch the probes together, and set for exactly 000, or note the difference in readings)

Place one probe on the "BATT" Terminal, and the other on the "TACH" terminal..this is the primary side..It should read less than an ohm, but MORE than 000, If it's 000, you have a shorted coil..toss it get an oil filled one. But it shouldn't run either...

Then move your probes over to the secondary side, set your meter for R X 10k, place one probe on the "BATT" Terminal and the other on the rotor carbon pickup, The reading here should be between 6000 and 30,000 ohms. Much outside , toss the coil.

The wire from the solenoid should be on the "R" or "I" terminal of the solenoid. It runs from the starter to the HEI Pink wire and joins together before the coil plug..It supports power during cranking mode if the Ignition is not a later model "Duel Contact" switch..(eliminated the need for secondary wires) If this wire is shorted to anything, It will melt the wires..

The pink wire , that comes from the Switch, used to go to the resistor, or resistor wire, If the resistor has shorted, or the resistance wire has frayed (cotton clad wire) and is touching ground, it will melt wires..In either case you do not need the resistor/wire..pull it and run the wire direct.

To eliminate or include the wires, just run a jumper of the same gauge wire to the HEI direct and the battery, start and run it, If it doesn't melt, it's the wires in the harness..If it does it's the coil. Remember, to shut it off you have to pull the battery / HEI jumper..

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Old 02-17-2006, 05:40 PM
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New coil tests are now done with the coil off the distributor, and simulated running conditions, modules as well. These tests are more accurate than ohm'ing the coils out, and tests them at both cold and operating temps.

Auto Zone stores usually have these testers, and even the counter people that work there can correctly test the coil and module for you.
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Old 02-17-2006, 06:59 PM
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The main concern is "melting the insulation".

This only means that a wire is shorted to ground and there is no means of protection (of the wiring).

The original GM harness had fuse links that would prevent this.

My fear is that the replacement harness does not include fuse links or some kind of overcurrent protection.

Go back and check your harness kit and make sure the fuses and fuse links are installed or you could have meltdown.

vicrod
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Old 02-17-2006, 08:43 PM
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When does the wire get hot ... when cranking?
What are your grounds like? I've seen and head of strange melt-downs due to circuits not being able to find a proper ground.

Make sure that your engine is well-grounded to both the frame and to the body. I like to run a 4-ga wire from the block to the frame as close to the starter as possible, and then a much lighter braided wire from the engine to the body.

Also be sure to use a fusible link where appropriate. Doc knows Chevy stuff inside-out, and should be able to tell you all of the locations.
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Old 02-17-2006, 09:40 PM
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Do a search for anything relating to grounds in this forum, docvette has posted numerous times the proper grounding of a vehicle, (really should be a sticky post)
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Old 02-17-2006, 11:08 PM
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RESISTANCE, or over resistance is responsible for the melting of the insulation. If the current load is larger than the wire is rated for, as in a 20 guage wire not being able to resist the current induced heat produced by the end user, the insulation will melt.

Grounded wire is the ultimate resistance. A component that has failed, and is causing a higher load resistance them it should, like a coil that is partially layer shorted, will cause overloading, and if severe, melting of the insulation.
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Old 02-18-2006, 03:53 AM
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Doc here,

Here is the start circuit for a 71 Elcamino..



The primary wire from the ignition switch is (supposed to be) purple...and ties to the red wire and goes to the fuse link and the alternator. This wire is the resistance wire..toss it..and replace with a straight run of wire... you no longer need it.

The secondary wire to the coil is Yellow..it runs from the solenoid direct to the coil. This wire could have a short on it back feeding through the purple wire.

Depending on the size of the fuse link, and the size (gauge) of the wires for the ignition, The weakest link in the system is going to go first...if the link is 60 amps and the wire is 20 gauge..guess what's going first? Especially on a less than Dead short situation..

Your Coil should be pulling down about 12 amps..If it were breaking down under heat as was mentioned, it may reach 20 or 30 amps or more in a few minutes of run time..

Just jump the coil with a jumper to the coil from the battery the same size as the stock wire and run it, If it starts to heat or melt..Toss the coil.

If not..Chase those wires in the diagram above one of them has a redundant short less than the link ampicity..

Doc
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