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mark houghton mark houghton is offline
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Join Date: Jul 2008
Location: Central Washington State
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Fred, I concur with using the delay ignition relay. IF there's gonna be fuel in there, might as well ignite it properly. Mine has never been hooked up when the PO installed MSD, but I can fix that easily.

Here's Wikipedia's list of dieseling reasons:

This condition can occur for a multitude of reasons:

Built-up carbon in the ignition chamber can glow red after the engine is off, providing a mechanism for sparking unburnt fuel. Such a thing can happen when the engine runs very rich, depositing unspent fuel and particles on the pistons and valves. Similarly, non-smooth metal regions within the piston chamber can cause this same problem, since they can glow red. It has also been suggested that an improperly rated spark plug can retain heat and cause the same problem.
A carburetor that does not close entirely (or a leaking fuel injector in our case) can contribute to running once the engine is off, since the extra fuel and oxygen mixture can combust easily in the warm piston chamber. Similarly, hot vaporized oil gases from the engine crankcase can provide ample fuel for dieseling.
Incorrect timing.
An engine that runs too hot or too lean may produce an environment conducive to allowing unspent fuel to combust.
An idle speed that is too fast can leave the engine with too much angular momentum upon shutdown, raising the chances that the engine can turnover and combust more fuel and lock itself into a cycle of continuous running.
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Mark H. 1987 930, GP White, Wevo shifter, Borla exhaust, stock everything else. The result of a massive Pelicanite good will fire recovery effort. Truely an open book, ready for the slippery slopes to modification.
Old 09-23-2011, 10:51 AM
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