LT5 Spark Plugs - ZR-1 Net Registry Forums

Nick · 08-18-2005

What spark plugs are you guys running? My lightly modified LT5 runs very well on the GM specified AC Delco 41-913's. I recently tried a set of Rapidfire #5's and I'm having some problems with detonation. I think the plug's heat range is too hot, so I'm going to try a set of Autolite double platinums, for no other reason than availability and price ($4 apiece versus $10 apiece for the AC Delco 41-913's).

My research indicates that the Rapidfire #5 will work, if you start the engine and don't warm it up before driving, and if you do not drive it aggressively.

Anybody here fit that criteria?

I also understand that the Rapidfire #9's might work better. Comments?

1990 quasar blue · 08-18-2005

Nick, I'm currently running the colder of the rapid fire plugs. I get some hesitation, especially when the car isn't completely warmed up. Mark Haibeck said that the rapid fires are known to cause that problem and recommended the NGK TR7IX Iridium. I ordered a set and then realized that they are a tapered seat, and having a 1990, I would have to do the over torque thing. I'm still on the fence about whether or not to do it so I can't tell you if they made an improvement.

RiceEatingZR1 · 08-18-2005

NGK Plugs ROCK! I have never heard anything bad about them I have a friend that has them in his Firebird and loves them, I plan on putting them in my car when its time.

as for the rapidfire plugs I have not heard anything good on them.

Nick · 08-19-2005

UPDATE.

Installed the Autolite double platinums last night, in stock heat range. Car runs fabulous. No detonation and coolant temps lowered slightly.

Its nice having my ZR-1 back again!

ZR1 MK · 08-23-2005

Good to here your car is running well again.
I use splitfire plugs without any problems.

08-18-2005	#1
Nick Join Date: Jul 2005 Location: Auburn, Washington Posts: 586	LT5 Spark Plugs What spark plugs are you guys running? My lightly modified LT5 runs very well on the GM specified AC Delco 41-913's. I recently tried a set of Rapidfire #5's and I'm having some problems with detonation. I think the plug's heat range is too hot, so I'm going to try a set of Autolite double platinums, for no other reason than availability and price ($4 apiece versus $10 apiece for the AC Delco 41-913's). My research indicates that the Rapidfire #5 will work, if you start the engine and don't warm it up before driving, and if you do not drive it aggressively. Anybody here fit that criteria? I also understand that the Rapidfire #9's might work better. Comments? __________________ Nick ZR-1 Net Registry Founding Member #32 - lapsed...

08-18-2005	#2
1990 quasar blue Join Date: Feb 2004 Location: Ma Posts: 404	Nick, I'm currently running the colder of the rapid fire plugs. I get some hesitation, especially when the car isn't completely warmed up. Mark Haibeck said that the rapid fires are known to cause that problem and recommended the NGK TR7IX Iridium. I ordered a set and then realized that they are a tapered seat, and having a 1990, I would have to do the over torque thing. I'm still on the fence about whether or not to do it so I can't tell you if they made an improvement. __________________ 1990 ZR1 #2574 Medium Quasar Blue Metallic 1 of 19

08-18-2005	#3
RiceEatingZR1 Join Date: Feb 2004 Location: Aurora, IL Posts: 309	NGK Plugs ROCK! I have never heard anything bad about them I have a friend that has them in his Firebird and loves them, I plan on putting them in my car when its time. as for the rapidfire plugs I have not heard anything good on them. __________________ -Shaun 1991 Charcoal Metallic ZR1 #730 [URL="http://www.cardomain.com/ride/2649606"]http://www.cardomain.com/ride/2649606[/URL] [URL="http://community.webshots.com/user/shaun91zr1"][/URL] [IMG]http://img.photobucket.com/albums/v211/RiceEatingZR1/Forum%20Sig/Sig1.gif[/IMG]

08-19-2005	#4
Nick Join Date: Jul 2005 Location: Auburn, Washington Posts: 586	UPDATE. Installed the Autolite double platinums last night, in stock heat range. Car runs fabulous. No detonation and coolant temps lowered slightly. Its nice having my ZR-1 back again! __________________ Nick ZR-1 Net Registry Founding Member #32 - lapsed...

08-23-2005	#5
ZR1 MK Join Date: Aug 2005 Location: NY Posts: 143	Good to here your car is running well again. I use splitfire plugs without any problems. __________________ Mike 427 cu in LT5 [URL="http://zr1mk.weebly.com"]http://zr1mk.weebly.com[/URL]