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Old 10-13-2010, 03:14 PM   #1
eZ
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Default Dieseling please help

Ill try and give as much info as possible. Its a 347, 10.5:1, afr heads, airgap blah blah...Engine diesels pretty bad when I shut it off. I though it might be a timing problem but after a few beers I realized that when I turn the motor off there is no spark so it cant be timing. So I left the timing at 16 initial. The cam is a xe282hr. The carb is a lil ole 600 edelbrock. seems to be running a lil bit rich when I inspect the plugs. I leaned it out a bit and still on the rich side. still diesels. Im running 91 oct which is the highest octane I can run here in so. Cal. I dont want to drive her anymore until I get this fixed, fear of burning up a valve. Next step Ill try a colder spark plug. Idle is set at about 900 in park and 700 in drive. If I back the idle down it wants to stall with that cam.
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Old 10-13-2010, 03:33 PM   #2
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Try pulling timing at idle first.
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Old 10-13-2010, 03:45 PM   #3
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pulled to 12 degrees and still diesel
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Old 10-13-2010, 03:58 PM   #4
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Dieseling is most often caused by the idle set too high.
Try shutting it off in "drive".
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Old 10-13-2010, 04:02 PM   #5
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is it hard to start up to? needle seat in the carb could be leaking or the float valve is set too high.
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Old 10-13-2010, 04:05 PM   #6
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This could be caused by a number of factors
Too Lean (hot spots) - check for vacuum leaks
Carbon buildup (again hot spots being the carbon)
Octane of the fuel too low (ignites at too low of a compression)
Wrong spark plugs (too hot)
And others but this is where I usually start

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Old 10-13-2010, 04:06 PM   #7
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Quote:
Originally Posted by 1971mach1 View Post
Dieseling is most often caused by the idle set too high.
Try shutting it off in "drive".
Kinda. Usually because the front primaries are open too far. You can get the same idle with the front primaries damn near closed.
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Old 10-13-2010, 04:33 PM   #8
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try a different brand of gasoline (different formulas have an effect). Most if not all of my experiences with dieseling engines are from carbon build up or idle too high.
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Old 10-13-2010, 04:41 PM   #9
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Quote:
Originally Posted by cprstreetmachines View Post
Kinda. Usually because the front primaries are open too far. You can get the same idle with the front primaries damn near closed.
Ill try opening up the idle screw and backing off the throttle. Its not running lean. It diesled even when it was running way rich.

Im running the plugs that my AFRs called for.
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Old 10-13-2010, 04:54 PM   #10
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Quote:
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Ill try opening up the idle screw and backing off the throttle. Its not running lean. It diesled even when it was running way rich.

Im running the plugs that my AFRs called for.
How do you like the AFR heads? I've been beating myself up trying to make the decision between afr and trickflow.
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Old 10-13-2010, 04:54 PM
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