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Spark plug gapping....

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Old Nov 13, 2007 | 07:20 AM
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Default Spark plug gapping....

Would like to replace my plugs in my 383 and I have all the shop manuals for my car. Even though the vette never came with a 383, can I use the same gapping as listed in the manuals?
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Shane
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Old Nov 13, 2007 | 07:42 AM
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From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
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normally yes,

but if you are runnning and an HEI ignition you can open the gap up to as much as .050 depending on the application. Though generally i would say .045 is right for most HEI applications



tim
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Old Nov 13, 2007 | 08:30 AM
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Originally Posted by sweethence
normally yes,

but if you are runnning and an HEI ignition you can open the gap up to as much as .050 depending on the application. Though generally i would say .045 is right for most HEI applications



tim
Great, thanks. I forgot about the HEI and that is a good point. Would you happen to know of a good primer on the subject?
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Old Nov 13, 2007 | 09:13 AM
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From: Wilmington DE, Drive it like you stole it, 68 327 4 speed coupe
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Originally Posted by ShaneLU97
Great, thanks. I forgot about the HEI and that is a good point. Would you happen to know of a good primer on the subject?
I only know the old rules of thumbs off the top of my head, i.e when you raise compression or go to forced induction you must reduce the gap about .004 for every 50 hp. And when you add an HEI you can open the gap from .002-.005 from standard, with some aftermarket ingition companies ( mallory, DUI, etc) claiming you can open up to .055 depending on application. I run a DUI HEI unit at .040, and then read the plugs and adjust from there. It seems happy at .040 so thats where i keep it


some more expert techs please chime in
tim

Last edited by sweethence; Nov 13, 2007 at 09:15 AM.
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Old Nov 13, 2007 | 09:40 AM
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I run .040 in my 383 in my 61 with HEI. Seems to burn well. NGK's.
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