Spark Plug Question

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Dec 14, 2011 | 09:59 PM

hcb1700

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Spark Plug Question

Guys I have a 2001 LS1 with an MS4 Cam, and PRC stage 1 LS6 heads and have a question on the spark plug gap. What should the gap be set too in with a setup like this? What are guys running?

Dec 15, 2011 | 09:57 AM

hcb1700

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32 views and no replies?

Dec 15, 2011 | 11:15 AM

ljsracing19j

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.035 or .060 depends on the plug. .035 with a plain plug .060 with a platinium. But really i would go with what the manufacturer recomends.

Dec 15, 2011 | 11:21 AM

Russ K

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As per a GM TSB, 12571164 (AC Delco 41-985) plugs are gapped at .040 when made.

Russ Kemp

Dec 15, 2011 | 02:59 PM

sjsingle1

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but before that TSB...the gap was .060

Dec 15, 2011 | 07:18 PM

ZeeOSix

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Quote:

Originally Posted by sjsingle1

but before that TSB...the gap was .060

True ... but GM changed the gap to 0.040" for some reason. Not sure what it was, but maybe because the OEM coils were being over worked (?).

Dec 15, 2011 | 10:11 PM

hcb1700

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I'm going to go with iridium plugs and need to know what I should gap them too. I'll probably gap them to .040.

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Dec 16, 2011 | 04:58 PM

ZeeOSix

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Quote:

Originally Posted by hcb1700

I'm going to go with iridium plugs and need to know what I should gap them too. I'll probably gap them to .040.

If the Iridium plugs are specifically for your engine, they should come factory gapped at 0.040". The TSB from GM (AC-Delco) says the plugs will come factory gapped at 0.040" and to NOT re-gap them. I put some NGK Platinums factory gapped at 0.040" in my LS6 and it runs fine.