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Spark plugs
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 35
Likes: 7
From: Monroe Louisiana
Spark plugs
I recently purchased a 2007 c6 corvette. It’s got a stage three texas speed cam I can share all the specs if needed , ported heads, fast lsxr intake manifold, catless headers. I noticed one of my spark plug wires wasn’t staying on the plug properly anymore so I figured I’d go ahead and replace those along with the plugs. Does anybody have any ideas on what spark plugs I should run? Thanks for the help!
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
I'd run the plugs GM recommends for the LS7/LS9 engines. You can get a different plug to work, but you won't get a better one. 41-104 from memory. If that's not it, your local parts guy can set you straight.
And welcome to the forum
And welcome to the forum
Race Director
Joined: Mar 2011
Posts: 13,262
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From: SW Florida
2021 C6 of the Year Finalist - Modified
Thread Starter
Intermediate
Joined: Dec 2021
Posts: 35
Likes: 7
From: Monroe Louisiana
Any idea what I should gap them at? Or should I leave them at the stock .04? Thanks!
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
I've never touched or even checked the gap. They arrive with a sleeve protecting the threads and electrode. If the box isn't beat all to hell, they're fine. I've run them in LS engines from 450 to well over 700hp. The only spark plug trouble I had in any of these engines happened when I tried the TR6 plugs that some on this site are enamored with. Won't be doing that again.
Race Director
Joined: Jul 2005
Posts: 12,058
Likes: 3,590
From: Central MO
I've never touched or even checked the gap. They arrive with a sleeve protecting the threads and electrode. If the box isn't beat all to hell, they're fine. I've run them in LS engines from 450 to well over 700hp. The only spark plug trouble I had in any of these engines happened when I tried the TR6 plugs that some on this site are enamored with. Won't be doing that again.
I'm surprised the LS9 plug wouldn't be one heat range colder than the one specified for the LS3. Pretty typical recommendation for FI.
For the record, I ran TR6 plugs in my Magnacharged 2002 Avalanche running 10 psi. Granted it was just a 5.3; they ran fine with never an issue. I have read others who also reported issues with them.
Le Mans Master
Joined: Dec 2005
Posts: 7,002
Likes: 1,687
From: Southeast TX
Even though I know the gap is likely close, I'm too **** (typical engineer, I guess) to not check them and make sure they are all precisely gapped. I recently found one of 6 plugs pretty far off coming out of the box when changing plugs in the wife's 2014 Charger 3.6 V6.
I'm surprised the LS9 plug wouldn't be one heat range colder than the one specified for the LS3. Pretty typical recommendation for FI.
For the record, I ran TR6 plugs in my Magnacharged 2002 Avalanche running 10 psi. Granted it was just a 5.3; they ran fine with never an issue. I have read others who also reported issues with them.
I'm surprised the LS9 plug wouldn't be one heat range colder than the one specified for the LS3. Pretty typical recommendation for FI.
For the record, I ran TR6 plugs in my Magnacharged 2002 Avalanche running 10 psi. Granted it was just a 5.3; they ran fine with never an issue. I have read others who also reported issues with them.
I'd use stock plugs on a stock engine. Once you turn the wick up with cam/heads or F/I, I feel better with a step colder plug. I ran two steps colder on a 660 rwhp Vette and the thing felt sluggish at low rpm around town. Replaced with the 41-104's and all was good.
If I was racing a whole lot, and timeslips really mattered, a cheaper plug like the TR6 might be a decent option if changing the plugs often made me more confident. Then there's the charging system problems that happen on some C6's when using TR6's. Don't really understand that, but there are too many happenings to ignore.
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Thread Starter
Intermediate
Joined: Dec 2021
Posts: 35
Likes: 7
From: Monroe Louisiana
I do eyeball them pretty hard, but yeah, my eyeball's not quite that good. TR6's are the same heat range as the 41-104's. Yes, one heat range cooler than stock LS2/3. I ran some that did fine and then I had a set that were just bad. Pulled them out and checked everything I knew to check. No cracks, no obvious signs of anything amiss. Re-installed and they still ran like crap. They ran fine until the boost/rpm got up there a bit and then things went south. Changed back to AC plugs and all was good.
I'd use stock plugs on a stock engine. Once you turn the wick up with cam/heads or F/I, I feel better with a step colder plug. I ran two steps colder on a 660 rwhp Vette and the thing felt sluggish at low rpm around town. Replaced with the 41-104's and all was good.
If I was racing a whole lot, and timeslips really mattered, a cheaper plug like the TR6 might be a decent option if changing the plugs often made me more confident. Then there's the charging system problems that happen on some C6's when using TR6's. Don't really understand that, but there are too many happenings to ignore.
I'd use stock plugs on a stock engine. Once you turn the wick up with cam/heads or F/I, I feel better with a step colder plug. I ran two steps colder on a 660 rwhp Vette and the thing felt sluggish at low rpm around town. Replaced with the 41-104's and all was good.
If I was racing a whole lot, and timeslips really mattered, a cheaper plug like the TR6 might be a decent option if changing the plugs often made me more confident. Then there's the charging system problems that happen on some C6's when using TR6's. Don't really understand that, but there are too many happenings to ignore.