AC Iridium Spark Plug Gap
05-08-2011, 10:02 AM
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AC Iridium Spark Plug Gap I am going to change plugs in my 2000 Z28.
I bought the AC 41-110 Iridium plugs to replace taht are gapped at .040.
The manual states the gap should be .060.
I realize that the 41-110 is not the original plug the engine used, but thathas me confused a bit.
I have done several searches and read several threads here with varying opinions.
So, should I gap these .060 or leave them pre-gapped at .040?
I bought the AC 41-110 Iridium plugs to replace taht are gapped at .040.
The manual states the gap should be .060.
I realize that the 41-110 is not the original plug the engine used, but thathas me confused a bit.
I have done several searches and read several threads here with varying opinions.
So, should I gap these .060 or leave them pre-gapped at .040?
05-08-2011, 12:03 PM
#2
You should gap them to .050........it's perfect for N/A LS1's from bone stock to 650 RWHP.
.060 is too much..... .040 is getting close to too little (unless you're running nitrous).
I've done allot of experimenting when my car was bone stock and with my built 427ci. I tried gaps from .060 to .040.......there was absolutely ZERO difference in performance and from what I could tell ZERO difference in fuel burn from .040 - .060. Therefore, I've been using the middle road..... .050
.
.060 is too much..... .040 is getting close to too little (unless you're running nitrous).
I've done allot of experimenting when my car was bone stock and with my built 427ci. I tried gaps from .060 to .040.......there was absolutely ZERO difference in performance and from what I could tell ZERO difference in fuel burn from .040 - .060. Therefore, I've been using the middle road..... .050
.
05-08-2011, 02:17 PM
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INFORMATION
Bulletin No.: 03-06-04-060B
Date: July 30 2008
Subject:
Information on New Spark Plugs and Gapping
Models
Attention: Please disregard the Set Gap Per Vehicle Specification statement on the side of an ACOelco(R) Iridium Spark Plug Box. The statement will be removed from the boxes in the future.
Supercede:
This bulletin is being revised to add the Chevrolet SSR and the 2005 Pontiac GTO. Please discard Corporate Bulletin Number 03-06-04-060A (Section 06 - Engine/Propulsion System).
^ 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 1.01 mm (0.040 in) when the spark plug is made.
Notice: 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.
Bulletin No.: 03-06-04-060B
Date: July 30 2008
Subject:
Information on New Spark Plugs and Gapping
Models
Attention: Please disregard the Set Gap Per Vehicle Specification statement on the side of an ACOelco(R) Iridium Spark Plug Box. The statement will be removed from the boxes in the future.
Supercede:
This bulletin is being revised to add the Chevrolet SSR and the 2005 Pontiac GTO. Please discard Corporate Bulletin Number 03-06-04-060A (Section 06 - Engine/Propulsion System).
^ 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 1.01 mm (0.040 in) when the spark plug is made.
Notice: 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.
I am going to change plugs in my 2000 Z28.
I bought the AC 41-110 Iridium plugs to replace taht are gapped at .040.
The manual states the gap should be .060.
I realize that the 41-110 is not the original plug the engine used, but thathas me confused a bit.
I have done several searches and read several threads here with varying opinions.
So, should I gap these .060 or leave them pre-gapped at .040?
I bought the AC 41-110 Iridium plugs to replace taht are gapped at .040.
The manual states the gap should be .060.
I realize that the 41-110 is not the original plug the engine used, but thathas me confused a bit.
I have done several searches and read several threads here with varying opinions.
So, should I gap these .060 or leave them pre-gapped at .040?
05-09-2011, 10:37 AM
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Damn, I just installed 41-110 plugs yesterday and didnt play with the gap. I checked one and if I remember correcty it was at 0.040" so I left them alone.
Last edited by alamantia; 05-09-2011 at 12:31 PM.
05-12-2011, 08:20 AM
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as someone else posted, GM revised the gap on LS motors to .040. if you do a search for spark plugs on any parts site, even on standard copper plugs, it comes up with .040 gapped plugs (NGK2238) instead of the previous .060's (NGK3951). Personally, i think platinum and iridium plugs offer little to no benefit for the added cost. I buy regular copper v-power NGK TR-55's (3951), and gap them to .050".
i know someone with a grand am 3.4L, which uses the same plugs as an LS1... it came with iridiums from the factory. we put TR-55's in it and didn't lose any fuel economy.
i know someone with a grand am 3.4L, which uses the same plugs as an LS1... it came with iridiums from the factory. we put TR-55's in it and didn't lose any fuel economy.
