NGK TR55 gap question? ??
08-05-2011, 10:35 AM
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NGK TR55 gap question? ??
Picked up some ngk tr 55 spark plugs yesterday. Checked the gap and they are set to. 060 but I looked up the specs of. The oem spark plugs for my truck and they are set to .040. Should I close them down to. 040 or run them how they come??
08-05-2011, 10:49 AM
#4
A TR5 should come pre-gapped around .035-.037 You may need to widen the gap slightly, so be sure to check them all. The part number will be 2238.
https://www.performancetrucks.net/fo...thread-456660/
https://www.performancetrucks.net/fo...thread-456660/
08-05-2011, 10:58 AM
#6
Originally Posted by GM TSB
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.
08-05-2011, 11:12 AM
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.040" seems to be the most up to date gap setting from GM. They used to recommend .060" with their old platinum plugs, but changed to .040" and issued a new plug number that was pre-gapped to that spec. Of course gap can be adjusted for every application so your results may vary, but .040" would be a good place to start.
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08-05-2011, 03:56 PM
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Those are fine Alex.... GM changed the gap due to the spark plug material. The TR55 are copper (softest) and are gapped at .060" per GM so they would last longer. The Iridium (hardest) are factory set at .040" because the plags will not ware out as fast due to the harder material of the plug.
08-05-2011, 04:54 PM
#10
+1 The newer OEM plugs are iridium, which is a harder metal than the copper TR55's that you just bought, and they require a smaller gap, so either keep what you have (TR55's) and leave the gap alone, or just open the gap on the TR5's if you don't want to go back to the store again.
FWIW, bending the ground, whether it is to make the gap clearance larger or smaller, is totally acceptable, just be sure not to damage the electrode in the process (this is especially important with iridium plugs as the iridium tip can easily break off). I use needle nose pliers on the ground to set the gap when necessary.
Also be aware, that your new copper plugs will have a shorter service life than the factory iridiums which were in there, which can easily go 100k on a properly running engine. Expect to change the TR55's somewhere between 24 to 30k
FWIW, bending the ground, whether it is to make the gap clearance larger or smaller, is totally acceptable, just be sure not to damage the electrode in the process (this is especially important with iridium plugs as the iridium tip can easily break off). I use needle nose pliers on the ground to set the gap when necessary.
Also be aware, that your new copper plugs will have a shorter service life than the factory iridiums which were in there, which can easily go 100k on a properly running engine. Expect to change the TR55's somewhere between 24 to 30k