Since I am pretty newcomer poster to this C-Forum, I likely want to use this opportunity to seek and search for an answer, re my so-called stocker "Platinum Sparkplugs" labelled NGK.

Last year, looking for further performance enhancements, I decided to exchange stock SP and stock SP-wires. Hence, after intense research and evaluation, my routing to go cleared-up as follows: Combo TAYLOR THUNDERVOLT 409 RaceWires (Spyro-wound) plus the famous ex german patented BERU SILVERSTONES. Just let me mention, after installation, I was definetely able to notice a totally strong, stable and smoothed-out idle at exactly 650rpm indicated :smash: . The rpm-indicator stays since as glued-on. Saying, this is one EXCELLENT performance-combo IMHO, just you loose AM-RDO due to EMI. But on the other hand, all the on-board CPU's seem not being interfered at all.

Now as for the exchanged SparkPlugs (~6'000km spirited to hard driving), I could observe:
- NO MORE pucks on the mass-electrodes, but you can see where they were
- The SP showed zero signs of any bad engine management (t/rich or t/lean)
- Despite missing pucks, all the gaps were correct within specs (1.5mm)
- All the SP sat in their threads with almost varying torque, some VERY hard
- Number-3 SP (left Cyl-bank, second front) was even NOT torqued, just sitting stiff in the threads
- aLL 8 SP were nicely fit into the threads by some anti-seize, thanx GM
- The Type-Indicator on the ceramical isolators shows as follows
>>>>>>>>>== NGK - PTR5C - 13 ==<<<<<<<<<<

Please, could some of you highly ranked Engine-Techs ;) post some claryfying facts to this matter; eg, are those in fact Platinums, or,may be not? As always => THANK YOU ALL!!

To the shame of my GM Dealer's "Chief of the Maintenance-Unit", nowbody there could reply to my inquiry......... :mad

 

SwissVette_Joe,

I'm not a guru, but maybe I can help.. The Stock Plugs installed in the domestic C5s are AC Delco platinums (41-931). A lot of guys who race C5s switch to NGK-TR55 (these are copper, not platinum). There is also a Platinum version of the NGK plug (TR-55VX).

It sounds like the part numbers are completely different in Europe. Here is a link to a very nice tip on changing the plugs. You will see photos of the stock, and copper plugs. It should be easy to tell the difference.

http://www.vetteguru.com/mods/ignition/

Hope this helps.


[Modified by SDVette, 2:28 PM 1/16/2002]

 

I had the same plugs in my car from the factory. I checked NGK's web site for info but they do not list them?!? They DO list P/N: TR55VX as their OEM plug for '99 'Vettes which is a platinum model.

I would assume that the PTR5C-13's are platinum as well because that's what GM states they put into all of our cars and the "P" in the P/N...

Also, there is no clear evidence of any platinum pucks on thes PTR5C-13's that I have like the factory installed Delco's have on themselves.

I'm kinda wondering what the real deal with these briefly used plugs is myself. I know there was a shortage of Delcos, thank God :D, during the time of my car's inception but where did these specific ones come from and under what design criteria were they manufactured.

Thanks