spark plug specs
Race Director
Joined: Apr 2017
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From: Hickory NC
2025 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
2020 C5 of the Year Finalist - Modified
St. Jude Donor '17 thru '26
You should be using .040 gap for your plugs. Most replacement plugs are coming with this gap already.
There was a Service Bulletin several years ago addressing the changed gap. TSB 03D-J-171 reads "A new spark plug has been released for use in the above vehicles.(Corvette 97-04) 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, ACDelco Part Number 41-985 (12571164), 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 to the gap required with the Platinum plug, or damage to the spark plug may result." NGK TR-5 plugs (also commonly used in the LS engines is pre-gapped at .040” also.
Torque your plugs to 11 ft pounds.
Be sure to use anti-seize on the spark plug threads.
There was a Service Bulletin several years ago addressing the changed gap. TSB 03D-J-171 reads "A new spark plug has been released for use in the above vehicles.(Corvette 97-04) 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, ACDelco Part Number 41-985 (12571164), 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 to the gap required with the Platinum plug, or damage to the spark plug may result." NGK TR-5 plugs (also commonly used in the LS engines is pre-gapped at .040” also.
Torque your plugs to 11 ft pounds.
Be sure to use anti-seize on the spark plug threads.
