[yellow69RS]

I know this far down in a topic it's easy to forget what year the OP is working on.... It's a 69. The amount of keys on the key ring might affect the lock cylinder operation but the contact portion is under the column by the brake pedal and connected to the lock cylinder by a long rod. His problem may still be in the ignition switch but the keys have no effect on it.

Jeff

[Everett#2390]

Originally Posted by jwalsh

I'm not sure I understant the following statement..."Also, there could be other hidden problems in the ign circuit, ie, ign sw itself as in burnt contacts between battery and ign, or, a dirty electrical connection at the battery junction block or horn relay buss bar or firewall connector. Current going through a resistive joint heats up, provides more resistance and reduces output voltage through the same interface." Gracias.

Follow the red lead from the clamp, fusible link, the short section from clamp tothe junction block, yes, the little 1"X1" block. Fusible links can corrode inside the insulation, any lumps in the insulation? Broken strands within or at any crimped termination.

The interface of terminals laying onto a mounting surface can be a high resistance joint, wire brush clean and reassemble.

Follow the red lead from the battery junction block across the radiator support to the horn relay buss bar and see there is another orange lead on the same bar. Orange lead is a fusible link. Disassemble and wire brush, check insulation for lumps - corrosion, reassemble. From the hr buss bar, there is another lead giong to alternator and to the firewall connection. Another place(s) for resistance. Once inside the dash, the red lead is crimped and splits, one leg to headlamp switch and fuse panel, BATT, the other to ign switch.

Any one of these connections can be resistive. Generally, a voltage measurement from the battery post to most any circuit in the electrical system, there should be less than 0.5 volts difference. Any measurement more, and a resitive joint is in the path. Same is true for negative side of circuits. Got to have a good return path also. Alt case should be grounded as well, there is alot of paint between the neg post and case.

Tip: connect the ground cable to battery to the block rather than the alt bracket, less resistance. Alum intake manifolds, if equipped, do not conduct current as well as iron.

[jwalsh]

Thanks Everett! That makes things very clear. I forgot to mention that I installed new battery cables as part of my "mini" engine bay restoration. It never occured to me that this may have caused an issue. I'll switch the ground from the aluminum manifold to the block and check all of the connections you mentioned.

I'll report back with my findings.

[Everett#2390]

You're welcome. As troubleshooting help, you might rig up a test light inside the interior, one lead to a good ground, the other lead to coil + terminal and if the engine dies, you will see if ign power is lost or not.

Light bulbs are easier to see than a meter reading.

[jwalsh]

Everett...I cleaned up all the terminals and going out to buy an ohm meter. Started the car and its getting 12V to the ing side of the coil and about 8v to the dist side while running which sounds like the problem Joe H described. Does this seem right to you? When I had the ballast resistor in the car wouldn't start. Confused.

[Everett#2390]

Twelve volts reads normal if the point set is open, no current flowing as in open circuit.
Close the point set, current flows, ign power at the coil + terminal gets less.
Keep adding more resistance in the ign power side and eventually, there will not be enough current for the coil to make a spark.
After 10-15 minutes of running, ign power might be down to 6-9 volts due to the cloth covered wire reducing battery voltage lower giving off the extra voltage as heat, thus the reason the wire is covered with cloth, protection from other wires in the harness from getting burned.

[jwalsh]

Update:

-After 15 minutes of running the ign side of the coil reads ~11volts
-The coil does not heat up enough that I can't touch it. In fact, I can hang on to it for as long as I like so its not very hot at all.
-I cleaned and reconnected everything that Everett suggested. With the positive battery cable disconnected, the coil ignition wire disconnected and the ign switch on, I get 1.0 ohms from alt BATT stud to the fusible link, 1.0 to the horn buss and 3.1 ohms from the alt BATT stud to the ign wire at the coil. I get 1.8 from the horn bus to the ign wire coming out of the firewall fuse box and 1.8 from the fire wall fuse box ign wire to the end of the ign wire at the coil. Does this sound right? What should be tested next?

The ohm meter jumps around and then settles down and start to count down. The readings above are after its settled down.

I was wiring up a test light and notice that the #7 spark plug wire was arc'ing off of the headers (big yellow spark). I pulled the wire and the boot had a huge tear in it. I've replaced it. What problems could this cause?

Lastly, I noticed that the voltage to the coil increases as RPM increases. Is this also normal?

Thanks again for your help.

[jwalsh]

I guess I'm ready to declare victory. I did everything the Everett suggested related to cleaning and reconnecting the ignition circuit. I can't say with a high level of confidence if it I had a bad connection or if it was the #7 spark plug wire arcing off the header but I warmed the car up and drove it for about 30 minutes without any issues.

Thanks for all of the suggestions and help. JW

[Everett#2390]

Good deal, JW. Drive it more and gain more confidence.

Ohm values look good. Yes, coil + voltage will increase with rpm's as the point set is closed more times per second than at idle.

Having an arcing plug wire would just make for a dead cylinder, not related to the engine dying after fifteen minutes, I believe.

[ss27]

I clicked back on this one to see what was goin on and the outcome.Ya see there J W didn,t i tell you Everett was a wiz with the wires a veritable electrical child protegy. He probably had a voltmeter as a play toy in his playpen as a child. WE are lucky to have him and for free to boot. Now aren,t you glad that you joined our family of CAMARO LOVERS.Alex

[Steptoe]

Nah ,I recon when he was little, and whe his patents where not around, got a fork and put it in the wall sockets...I mean if one surivive and has toys like that, they would have a damn good feel for this stuff.