spark plugs

[bob07]

which spark plugs would be the best for my 3400 in your opinion?

[99GrandAMSE]

... this is going to be a very individual taste so expect lots of differing opinions ... personally, I have the NGK Iridiums which I like :)

[TA^Guy]

I have used Bosch Platinums in almost all my vehicles and they were great, however I was less than pleased with them in the LA1 3400.

I would go with a quality ACDelco or NGK Iridium.

Then again I could show you a ACDelco that I blew the porcilin clean out of the metal threads and stayed attached to the plug wire while I was driving.

[rys99grandam]

Ac Delco all the way, Spark plug performance gains are minimal if anything at all. Might as well get something you know that works, and was designed accordlying.

[gectek]

well if you have higher output coils and or wires, then u should go with a plug that will make good use of those improvements, a copper plug will burn better than platinum, but they dont have the extended service life of plat. if you are running a diff tune, then def go with copper and 1 heat range colder...just a rule of thumb. it will keep KR and detonation down, and allow u to run more aggressive spark and AFR without the side effects, and i usually run autolite coppers because their numbering system is easy. for the .060 gap they are in the 600 series, and IIRC the stock number for out plug is 605 or 606 so for 1 heat range cooler, it would either be 604 or 605, just one number lower on the end. the .040 gap is in the 100 series IIRC...same system there though

[DomestikDemon]

when you say heat range, and talk about reducing KR and whatnot...you mean to accomplish this via a lower t-stat?

[gectek]

no...well u can, but you can better control Kr and Det through the heat range of the spark plug. the heat range is the effective length of the threaded electrode side of the plug. the longer the plug the hotter the heat range due to it dissipating heat to the head alot slower and keeping some of the heat still inside the combustion chamber. when u shorten the effective length then you lower the heat range and lower the overall combustion chamber temp before, during and after the spark event. cooler temps means less chance for any KR, detonation or preignition. but there is a draw back. if you run too cold, the plug pulls too much heat off and you run a change of fouling the plug out. but usually if you just run 1 heat range colder you shouldnt have any problems