AC DELCO 41-985 plug gap question .40 or .50 for bolt on car
06-14-2007, 12:47 PM
#1
TECH Fanatic
Thread Starter
iTrader: (21)
Join Date: Feb 2006
Location: Greater Chattanooga
Posts: 1,029
Likes: 0
Received 0 Likes
on
0 Posts
AC DELCO 41-985 plug gap question .40 or .50 for bolt on car ACDELCO 41-985 plug gap question?
--------------------------------------------------------------------------------
I have been reading 2 hours on plugs etc. I see where the factory is .60. Also I see this info below in anothe rpost and it says dont' regap .40 41985 plugs
I want to use the irdiums since they last a long time. I was thinking of using a gap of .50 to .52 Ihave a cam and bolt ons.
But can I regap the irdiums and not hurt the time. And indexing the plug seems like a pain.
2002-2004 GMC Sierra Denali
2003-2004 GMC Envoy XL
1998-2002 Pontiac Firebird
2004 Pontiac GTO
2003-2004 Hummer H2
with 4.8L, 5.3L, 5.7L or 6.0L V-8 Engine (VINs V, P, T, Z, G, S, N, U -- RPOs LR4, LM4, LM7, L59, LS1, LS6, LQ9, LQ4)
A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used.
Document ID# 1396703
--------------------------------------------------------------------------------
I have been reading 2 hours on plugs etc. I see where the factory is .60. Also I see this info below in anothe rpost and it says dont' regap .40 41985 plugs
I want to use the irdiums since they last a long time. I was thinking of using a gap of .50 to .52 Ihave a cam and bolt ons.
But can I regap the irdiums and not hurt the time. And indexing the plug seems like a pain.
2002-2004 GMC Sierra Denali
2003-2004 GMC Envoy XL
1998-2002 Pontiac Firebird
2004 Pontiac GTO
2003-2004 Hummer H2
with 4.8L, 5.3L, 5.7L or 6.0L V-8 Engine (VINs V, P, T, Z, G, S, N, U -- RPOs LR4, LM4, LM7, L59, LS1, LS6, LQ9, LQ4)
A new spark plug has been released for use in the above vehicles. The new spark plug has an Iridium tip instead of the current Platinum tip. Due to the different tip design, the gap of the spark plug has also changed. The new spark plug, P/N 12571164 with AC Delco P/N 41-985, is gapped to 1.01mm (0.040 inches) when the spark plug is made. The spark plug gap is set during manufacturing and should not be changed or damage to the spark plug may result. Any new spark plug found to not be properly gapped should not be used.
Document ID# 1396703
06-14-2007, 06:33 PM
#3
LS1Tech Administrator
iTrader: (3)
Join Date: Nov 2001
Location: Schiller Park, IL Member: #317
Posts: 32,046
Likes: 0
Received 1,493 Likes
on
1,075 Posts
Leave the gap at .040. If you want a different gap, use a different plug. IMO.
06-15-2007, 06:20 AM
#4
TECH Fanatic
Thread Starter
iTrader: (21)
Join Date: Feb 2006
Location: Greater Chattanooga
Posts: 1,029
Likes: 0
Received 0 Likes
on
0 Posts
Ok, I just know for a lot of bolt on cars people was running .50 wti the tr55's and the stock plugs on stock cars most was using the .60.
I didnt' want to have any issues running .40 with a cam car etc.
Thanks guys!
I didnt' want to have any issues running .40 with a cam car etc.
Thanks guys!
06-21-2007, 11:19 AM
#6
Teching In
Join Date: Jan 2007
Posts: 12
Likes: 0
Received 0 Likes
on
0 Posts
.040 works in my LS1 Replaced the .060 platinium plugs with 41-985 Iridiums. Checked the gap on the plugs and some were a bit off. Got them all to .040 before installing.
The Iridium is electroplated on and GM doesn't want you to scrape it off when regaping but the wrong gap is WORSE. There is a BCM flash which slightly affects timing which can be applied after installing these plugs but I'm staying as far away from the dealer as possible if I can help it. I also replaced my wires with GM Red Performance wires at the same time. Half the price of the black ones, are used on the Z06 and look terriffic.
BIGHANK
The Iridium is electroplated on and GM doesn't want you to scrape it off when regaping but the wrong gap is WORSE. There is a BCM flash which slightly affects timing which can be applied after installing these plugs but I'm staying as far away from the dealer as possible if I can help it. I also replaced my wires with GM Red Performance wires at the same time. Half the price of the black ones, are used on the Z06 and look terriffic.
BIGHANK 