INTERNAL OR EXTERNAL RESISTOR COIL??? - Chevelle Tech
Electrical & Wiring Troubleshooting electrical problems.

 
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post #1 of 8 (permalink) Old Jun 28th, 00, 7:17 PM Thread Starter
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On My 71 Chevelle (454) does this suposed to have an Internal Resistor Coil or an External Resistor Coil? Reason I as is that the Resistor line which feeds the positive side of the coil gets really, really hot... like smoking got??!! I don' like fire's I realize the wire is suposed to run warm but I'm sure it's not suposed to run that hot. Any help would sure be appreciated.

--Jim Morrison
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post #2 of 8 (permalink) Old Jun 28th, 00, 8:40 PM
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Jim,

Yes, there's definitely a problem. You might want to try to swap your ignition coil with another one to rule out that possibility. It should be one where it relies on external resistance as that is what the resistive wire does, provides a voltage drop.

I'm sure I-Man will have some helpful suggestions as well.

Joe

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[This message has been edited by Coppertop (edited 06-28-2000).]
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post #3 of 8 (permalink) Old Jun 28th, 00, 10:13 PM Thread Starter
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Thanks for the assistance Coppertop! I'm trying other coil's tomorrow, one being a Delco GM Brand Replacement for that model year and another one (if it still gives me problems) is a 12Volt Internal Resistor Coil. The engine harness is brand new, so is the dash harness. The only thing I'm leaving out, that I haven't mentioned before is that the alternator is only a 37 Amp Capacity Alternator. The owner before me stuck this one (37 Amp) in the car and can't be right with the car because it came with Air-conditioning originally. I'm in the process of having it built up to a 80 - 85 Amp alternator and a new 63 amp External Regulator (don't know what the old one is, no part #). Reason I'm doing this is the car has Air-conditioning and the system discharges on my Ampmeter on my dash when the Air-conditioning is engaged. Plus, when the air-cond is ON, the problem seems worse to me (maybe it's just in my head). If left running for a prolonged time the engine will suddenly stop and the resistor wire is very, very hot.

My question is, does the system running low on Amperage have some affect on the resistor wire heating up?? I've tried it on two different car batteries, and I still get the same result.
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post #4 of 8 (permalink) Old Jun 29th, 00, 8:40 AM
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Jim,

If you have all stock wiring, by all means go with external resistance coil. Here's something to check:

There should be a little capacitor (little metal can) with a wire lead going to the (+) side of the coil and is mounted to coil mounting brackets. Sometimes this can go bad and become an annoying intermittant short.

I can't rule out that the wimpy alternator may be causing some problems, but it's unlikely as not charging will result in a falling voltage in circuits instead of an "over voltage" making the wire hot. However, the A/C accessories such as the blower motor can act as a "generator" (because it is an inductive load) feeding some juice back into the system.

Check the capacitor first, ("condensor")--don't let the parts store confuse this with the condenser inside the distributor, tell them the location. Speaking of which, you are running stock points???

Then get the charging system back to stock before you start looking into wiring problems.

Hope that helps.

Joe



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post #5 of 8 (permalink) Old Jun 29th, 00, 9:45 AM
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The little4 capacitor Coppertop refers to is a noise suppressor, a capacitor, just as he says, there only for AM and CB radio useage, not needed for ignition system stability or other uses, just to dampen AM radio noise from the system. they indeed, can partial short, and cause problems.

I do, however, think you either have some sort of special coil eith the wrong primary windings or one that has internal insulation layer shorts. A layer short will cause the coil temp to go skyward, almost to smokin'.

All coils that run on resisted systems are external resistor type. Some performance aftermarket coils, like certain Mallory and Accel Super-Coil come with, and need, a second ballast resistor, to work with weak primary winding.
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post #6 of 8 (permalink) Old Jun 29th, 00, 11:23 AM Thread Starter
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Thanks guy's The system is running on stock points in the distributor. They look OK but I'm going to replace them sometime soon. There is no condenser on the positive side of the coil... but there is on attached to the backside of the External Regulator mounted near the front grill close to the left front headlight. The regulator is a universal application style "BIG A" auto parts store regulator (no parts number). I didn't install it, the previous owners did... could it (being the condenser) possibly be the culprit??

The coil I removed was a Delco Coil, but it did have a protruding bubble on the bottom side of it... I'm guessing from heat. I have the new Delco Coil but can't test it until tomorrow (Friday JUN 30 00) as I don't have my Alternator back from the rebuild shop yet.

When we get things back, installed and running I'll let you guys know how the system reacted. Hopefully I'll have good results.

Any more suggestions, I'm open and BTW out of curiosity is this supposed to be a 12Volt coil or a 6Volt coil??

Thanx again

--Jim

[This message has been edited by MY LS5 (edited 06-29-2000).]

[This message has been edited by MY LS5 (edited 06-29-2000).]

[This message has been edited by MY LS5 (edited 06-29-2000).]
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post #7 of 8 (permalink) Old Jun 29th, 00, 11:56 AM
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Jim,

The "condenser" (capacitor) connected to the voltage regulator is again for radio suppression. I doubt that would have any affect on your problem even in weird circumstances.

I'd say you should have a "12 volt coil" since at idle on my '70, the voltage at the coil's (+)terminal is 11.63 volts. Too high for a "6 volt coil"!

I've never actually heard that, I'm assuming the 6 volt ones are for the early cars with 6 volt electrical systems.

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post #8 of 8 (permalink) Old Jun 30th, 00, 10:23 PM Thread Starter
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OK! Got the parts back today... on the GM Delco coil we checked the voltage on the - negative side and read 10.4 volts. On the Internal Voltage reduction coil running at idle, it read 7.8 Volts on the negative side of the coil. Hmm... which to use?? The internal resistance coil did seem to run the resistance wire a bit cooler.

Boy did that alternator help out a bunch!! Went to 100 Amps. Cost me $55.00 to have the old one beefed up. I didn't think that was too bad. It sure is nice to have a charging system even when the air-conditioning is on. (Side note- Man, Iím sure impressed with the dimple core radiator on my Harrison stock tanks. At idle or pushed up to 1,000 or 1,200 RPM the water temp held to 150 to 160 degrees F. For a 454 Automatic with Air/Cond., I thought that was really impressive. It would always run @ least 200 to 215 degrees on up before. I know this is too cool as a running temp for the motor so I'll have to move up to a 180-degree thermostat from a 160.

Every thing else seems to check out OK, but which coil should I use and or what voltage is desired running to the points??

Thanks & Happy 4th to All,

--Jim
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