Engine run on

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Jun 11, 2013 | 12:48 PM

ungerp

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Engine run on

I am sure this isn't normal, but maybe someone can tell me how to fix it. I have a '55 with a 429, 8350 MSD distrib, 6AL box and blaster coil. It also has a Tuff Stuff one wire alternator wired directly to the positive side of the battery. the 6AL box is wire to the positive side of the starter solenoid. When I shut the switch off, the engine runs for 15-30 seconds longer for some reason. Is it a switch going bad or voltage from the alternator keeping the 6AL alive?

Jun 11, 2013 | 01:27 PM

old_dan

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From: Morgan Hill, CA

Do you have a wire going from your ignition switch to excite the alternator? If so, you can put a diode in that wire to prevent it from keeping the coil energized after you turn off the key. The same can happen if you wired in an idiot light for that alternator.

A Radio Shack #1N4001 diode would probably do the trick.

Dan

Jun 11, 2013 | 01:38 PM

ungerp

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Nope, just the single wire to the alternator. I don't believe there is even a second terminal on the alternator.

Jun 11, 2013 | 01:47 PM

old_dan

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From: Morgan Hill, CA

Then you have me stumped.

Do you have any form of amp meter, idiot light, or voltage meter?

Trace all of the wires on the "ON" terminal of your ignition switch. One of them is keeping some current on the coil wire. It's either that or the switch is starting to fail.

Dan

Jun 11, 2013 | 03:04 PM

ungerp

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I do have a voltmeter in the dash array. I will trace the wires on the on terminalof the switch, but I am betting on a switch going bad, even though pretty new.

Jun 11, 2013 | 03:35 PM

old_dan

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From: Morgan Hill, CA

I have spent time diagnosing problems going with the assumption that a new part is a good part. It sounds like your wiring is straightforward and it comes back to the key switch being bad.

Jun 11, 2013 | 06:15 PM

oldmerc

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From: Edmonton,Alberta

If this is a sometimes problem it could be as simple as good old fashioned hot carbon deposits in the combustion chamber. However if this happens every time no matter the engine temp length of trip etc. it does sound like electrical . try a elcheepo NAPA switch for comparison .