OEM spark # and plug gap confusion
Thread Starter
Safety Car
Joined: Oct 2004
Posts: 4,816
Likes: 132
From: Plano TX
OEM spark # and plug gap confusion
I've got a 99 with stock plugs 41-931. 56k miles.. Pulled 2 plugs and it looks like the gap is .062 with normal wear.. Owners manual says .060 I've seen other posts claiming a 41-952 as the stock plug with a .040 gap.. Looks like they may have changed plug numbers and gap specefications on the later model LS-1.. .062 sound ok? Car runs fine from idle to red line.. I'm going to the NGK TR55 copper plug as soon as spring rolls around. Just wanted to make sure I get the right plug and gap for my 99.. Or does it matter and whats the difference on the later model plugs and different gaps?? Why did GM change this? I'm sure someone knows
Last edited by David426; Jan 12, 2008 at 05:45 PM.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
I've got a 99 with stock plugs 41-931. 56k miles.. Pulled 2 plugs and it looks like the gap is .062 with normal wear.. Owners manual says .060 I've seen other posts claiming a 41-952 as the stock plug with a .040 gap.. Looks like they may have changed plug numbers and gap specefications on the later model LS-1.. .062 sound ok? Car runs fine from idle to red line.. I'm going to the NGK TR55 copper plug as soon as spring rolls around. Just wanted to make sure I get the right plug and gap for my 99.. Or does it matter and whats the difference on the later model plugs and different gaps?? Why did GM change this? I'm sure someone knows
The AC Delco part number is 41-985, and the GM part number is 12571164 ..... the new plug comes pre-gapped (correctly) at 0.040 look here for info on the plug ....
http://www.acdelcotechconnect.com/pd..._03D-J-171.pdf
