Duraspark info and testing Question
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Senior User
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From: Sonoma, CA
Duraspark info and testing Question
On my '76 F250 SC is it a Duraspark or Duraspark II system? Also, how can I test the retard circuit for assisting hot starts. I still get the occasional slow turn over when it's hot and I have fairly beefy all new cables and clean grounds. I also have a 1" phenolic spacer on the intake manifold. Can the retard be observed with a timing light whan turning it over or is there a wire I can check to see if the retard circuit is working or if there is one on this module? It has a blue grommet for sure and two 3 wire connectors I think.
Thread Starter
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Senior User
Joined: Feb 2006
Posts: 479
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From: Sonoma, CA
I'll check it out. The timing is at 12.5 btdc as the specs call for. So is it a Duraspark or Duraspark II system? Is the 12volts at the coil telling me it is doing its retard function?
Posting Legend
Joined: Sep 2001
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Yours is a Duraspark II system.
The 12 volts mentioned above can not be measured at the coil. During cranking the battery voltage is lowered due to the internal resistance of the battery. The resistance in connections and wiring also lowers the applied voltage. During cranking you should have about 7-10V at the coil + terminal.
You can test the timing with a timing light. If you currently run 10°BTDC while idling then during cranking you would get 0 to 15°ATDC while cranking. AFAIK it is supposed to be a nominal 20° retard but the timing components in individual modules vary widely. Some aftermarket units do not have timing retard circuits to make them cheaper.
Wiring diagrams can be found here:
https://www.ford-trucks.com/forums/member.php?u=1811
Ignition and starter test procedures can be found in any service manual.
Modules can be tested at most parts stores.
The 12 volts mentioned above can not be measured at the coil. During cranking the battery voltage is lowered due to the internal resistance of the battery. The resistance in connections and wiring also lowers the applied voltage. During cranking you should have about 7-10V at the coil + terminal.
You can test the timing with a timing light. If you currently run 10°BTDC while idling then during cranking you would get 0 to 15°ATDC while cranking. AFAIK it is supposed to be a nominal 20° retard but the timing components in individual modules vary widely. Some aftermarket units do not have timing retard circuits to make them cheaper.
Wiring diagrams can be found here:
https://www.ford-trucks.com/forums/member.php?u=1811
Ignition and starter test procedures can be found in any service manual.
Modules can be tested at most parts stores.
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