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. :thumbsdo: Anybody here fit that criteria? :confused:

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

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.

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

UPDATE.

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

Its nice having my ZR-1 back again! :thumbsup:

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