spark plug preferences?
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
Nothing wrong with the stock Iridium.
Unless you do something to change the spark gap requirements (forced induction) or heat range (again, FI), then the stock plugs are just fine.
I went to FI and changed to the ZR1 stock plug (still Iridium)
Elmer
Unless you do something to change the spark gap requirements (forced induction) or heat range (again, FI), then the stock plugs are just fine.
I went to FI and changed to the ZR1 stock plug (still Iridium)
Elmer
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
Just asking....
What is wrong with the stock Iridiums?
What is better about changing to a copper NGK plug that will need replacement in 20K or so miles when the OEM Iridium will go 50K and more without an issue?
I'm not going to even ask about the NOS or FI issues as the OP doesn't have anything except a NA stock car. He also asked for the stock OEM temperature range so I think a couple of suggestions presented don't use the stock temp range. I've read on here that the TR6 can cause alternator issues and I didn't use them because of that issue. I went with the ZR1's stock plug for FI.
Elmer
What is wrong with the stock Iridiums?
What is better about changing to a copper NGK plug that will need replacement in 20K or so miles when the OEM Iridium will go 50K and more without an issue?
I'm not going to even ask about the NOS or FI issues as the OP doesn't have anything except a NA stock car. He also asked for the stock OEM temperature range so I think a couple of suggestions presented don't use the stock temp range. I've read on here that the TR6 can cause alternator issues and I didn't use them because of that issue. I went with the ZR1's stock plug for FI.
Elmer
Race Director
Joined: Nov 2005
Posts: 14,548
Likes: 1,535
From: Supporting the Corvette Community at Abel Chevrolet in Rio Vista, CA 707-374-6317 Ext.123
St. Jude Donor '08
Just asking....
What is wrong with the stock Iridiums?
What is better about changing to a copper NGK plug that will need replacement in 20K or so miles when the OEM Iridium will go 50K and more without an issue?
I'm not going to even ask about the NOS or FI issues as the OP doesn't have anything except a NA stock car. He also asked for the stock OEM temperature range so I think a couple of suggestions presented don't use the stock temp range. I've read on here that the TR6 can cause alternator issues and I didn't use them because of that issue. I went with the ZR1's stock plug for FI.
Elmer
What is wrong with the stock Iridiums?
What is better about changing to a copper NGK plug that will need replacement in 20K or so miles when the OEM Iridium will go 50K and more without an issue?
I'm not going to even ask about the NOS or FI issues as the OP doesn't have anything except a NA stock car. He also asked for the stock OEM temperature range so I think a couple of suggestions presented don't use the stock temp range. I've read on here that the TR6 can cause alternator issues and I didn't use them because of that issue. I went with the ZR1's stock plug for FI.
Elmer
Safety Car
Joined: May 2006
Posts: 4,288
Likes: 129
From: Providence Forge, VA
St. Jude Donor '08-'09-'10-'11-'12
You are one of the few that gets it. There is nothing better then the stock Iridium AC Delco plugs for stockish applications. I see charging system faults, random misfires and other related issues frequently with aftermarket plugs in stock applications. Everyone just thinks (and reads the crap on here) about changing plugs and jumps on the bandwagon. There is no good reason to use aftermarket plugs in a stockish application. Avoid the potential headaches associated with aftermarket plugs until you go FI.
The stock plugs are as good as anything out there for normal applications.
Thread Starter
Drifting
Joined: Mar 2010
Posts: 1,901
Likes: 361
From: TX
I would like to stick with Iridiums. However, in the past I've had some quality issues with AC Delco plugs, and I'm wondering if Denso or NGK make a better quality Iridium replacement for the OEM plug.
Safety Car
Joined: Jun 1999
Posts: 3,570
Likes: 3
From: Austin, Singapore, Kuala Lumpur, Houston, Dallas, Hong Kong, Elgin, etc.. Texas
My tuner installed NGK TR55 but tried to gap them to .035". These are designed to be gapped at .055".
For the ~.040" gap, use the TR5.
I changed back to the AC Delco stock plug. I've never seen any evidence there is anything to be gained by going with the NGK TR5 or TR55.
For the ~.040" gap, use the TR5.
I changed back to the AC Delco stock plug. I've never seen any evidence there is anything to be gained by going with the NGK TR5 or TR55.
Team Owner
Joined: Nov 2006
Posts: 21,136
Likes: 212
From: Long Island New York
You are one of the few that gets it. There is nothing better then the stock Iridium AC Delco plugs for stockish applications. I see charging system faults, random misfires and other related issues frequently with aftermarket plugs in stock applications. Everyone just thinks (and reads the crap on here) about changing plugs and jumps on the bandwagon. There is no good reason to use aftermarket plugs in a stockish application. Avoid the potential headaches associated with aftermarket plugs until you go FI.
Tolero Apto Victum
Joined: Jul 2007
Posts: 9,669
Likes: 37
From: Woodlands TX
Moderator emeritus
Joined: Jun 2001
Posts: 18,599
Likes: 3,951
From: Jacksonville Florida BWO Dayton, Cincinnati, Bloomsbury NJ, Cincinnati
2015 C7 of the Year Finalist
I think the old rule was .010 less gap for every 50 RWHP added. Also, FI needs the smaller gap so you don't blow out the spark under high boost. Honestly? I switched to the ZR1 stock plug. It seems to be perfect for my situation. ~500 RWHP and a .040 gapped Iridium.
Elmer
Last edited by eboggs_jkvl; Dec 21, 2010 at 10:23 AM.
Drifting
Joined: Jun 2006
Posts: 1,730
Likes: 4
From: Delray Beach Florida
I put 50k Miles on the stock plugs, when I pulled them they still looked "ok" but not to my liking. I replaced them with the TR55's, and I have now have 25k miles on those plugs. I'll be pulling those plugs soon to replace them with new TR55's that came with my new MSD spark plug wires, I'll let you know how the TR55's held up for the 25k miles.
note:
I've never had any of the issues that some people say the TR55's cause. I also put the TR55's on my C5 for over 40k miles before it was gone.
I picked the TR55's b/c all of the performance shops I spook with told me they were the plugs to use, NOT b/c this forum told me to get them.
note:
I've never had any of the issues that some people say the TR55's cause. I also put the TR55's on my C5 for over 40k miles before it was gone.
I picked the TR55's b/c all of the performance shops I spook with told me they were the plugs to use, NOT b/c this forum told me to get them.
Race Director
Joined: Sep 2007
Posts: 16,557
Likes: 2,104
From: Peoria/Phoenix AZ
C6 of Year Finalist (performance mods) 2019
You are one of the few that gets it. There is nothing better then the stock Iridium AC Delco plugs for stockish applications. I see charging system faults, random misfires and other related issues frequently with aftermarket plugs in stock applications. Everyone just thinks (and reads the crap on here) about changing plugs and jumps on the bandwagon. There is no good reason to use aftermarket plugs in a stockish application. Avoid the potential headaches associated with aftermarket plugs until you go FI.
Sometimes it's funny to see how many people think there is always something out there that is better than original equipment. I recognize GM has to satisfy both the bean counters and the masses and therefore can't put the absolute best of everything on a $50K car. Some things just don't get better unless there is a specific need that applications require. That said, many mods are based on desire rather than requirements.
Race Director
Joined: Nov 2005
Posts: 14,548
Likes: 1,535
From: Supporting the Corvette Community at Abel Chevrolet in Rio Vista, CA 707-374-6317 Ext.123
St. Jude Donor '08
Sometimes it's funny to see how many people think there is always something out there that is better than original equipment. I recognize GM has to satisfy both the bean counters and the masses and therefore can't put the absolute best of everything on a $50K car. Some things just don't get better unless there is a specific need that applications require. That said, many mods are based on desire rather than requirements.