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Thread: Spark plugs for '73 S

  1. #1

    Spark plugs for '73 S

    I've heard bad things about using platinum plugs in this car, but can't seem to find anything other than the W3DPO's. Is anyone runing a different kind of plug that they are happy with?

  2. #2
    The only bad thing I ever heard about platinum plugs is that they are more expensive. I've been hearing it for 30 years!

    Bosch, NGK, Autolite and Champion all list a plug for our cars.

    I used to use a W265P21 Bosch plug in an early 2.2 S I had. My suspicions are that technology has come a long way and I would not be the least bit afraid of a standard platinum plug.
    For what it's worth try these 2 sites out:

    Also, the NGK search will turn up the 911-S as having 2-3bbl as the fueling system whereas the T lists "Ex K Jetronic and K Jetronic. The E displays "FI".

    Have fun.
    Early S Registry #235
    rgruppe #111

  3. #3

    Would you believe??

    I have a few sets of unused W265P21's...I keep thinking about screwing a set in sometime, but they're really a bit too cold for the driving I do these days. Some you might want to try

    I'm currently running the W4CS, as suggested by Gordon Ledbetter, one of this area's top early P car wrenches. They seem to work well for my driving. That is, mostly go with the (traffic) flow, but run to redline from time to time, when conditions allow being frisky. No track use.
    Paul D. Early S Registry #8 - Cyclops Minister of West Coast Affairs
    "Now, to put a water-cooled engine in the rear and to have the radiator in the front, that's not very intelligent." -Ferry Porsche (PANO, Oct. 1973)

  4. #4
    "when conditions allow being frisky"
    Now, I like the way you put that. Next time I'll tell the police to excuse me for being frisky. Think it'll work???

    Thanks for the heads up on the plugs.
    Early S Registry #235
    rgruppe #111

  5. #5
    I've used CS plugs exclusively for 15 years and love them. THey cost less than the original platinum version, and seem to last longer. Whether you want a W4 or W3 is a function of your application.

  6. #6

    Re: Would you believe??

    Originally posted by pwd72s
    Is the NGK B8ES for a '67S too? Or is B6ES better?

    What's good in a 2.7?

    I have a '67S and it's strangely fast. My friend with a new 2.2S engine (built and run-in already) can find no way to touch me... I don't know any history of the car but I love her.

    I met the old wrench who worked on her previously and he told me she's got a 2.7 in the back. But I doubt his words. Who would build a 2.7 and not update the tensioners or add an oil cooler or add CDI?

    But he did tell me to try NGK B9EV. Kinda cold ya?


  7. #7
    Blessed be the lowered RickS's Avatar
    Join Date
    Nov 2002
    Worshington State
    Originally posted by Lee
    I've used CS plugs exclusively for 15 years and love them. THey cost less than the original platinum version, and seem to last longer. Whether you want a W4 or W3 is a function of your application.
    Lee please define the differences btwn the W4 and W3. I have a relatively stock 2.4S. Thanks
    71 914 3.0, 82 SC, ESR 376, RG 307

    "The problem with the world is, the ignorant are cock-sure and the intelligent are full of doubt." Bertram Russell

  8. #8
    I really need to check the site more often! Rick, the number in the Bosch nomenclature refers to the heat range of the plug (the S is a silver electrode).

    I don't have my books in front of me, but I'll take a whack at explaining this from a layman's perspective. If I get this wrong, someone please correct me.

    I believe I'm correct in stating that the 3 is a colder plug than the 4. In Bosch's old 3 digit numbering system, I believe a higher number was a colder plug.

    Colder in this sense means that the heat path through the plug to the electrode is longer, so less heat is transferred and the plug does not get as hot. That keeps the plug from overheating in high performance engines that are used hard, but may prevent the plugs from getting hot enough to prevent fouling in mild driving. Since Porsche went to a CD system fouling is not much of a problem, but selecting the right heat range is still valuable.

    I've always been happy with the W4 for normal (frisky) driving, but I would probably use a W3 for a highly tuned S engine that gets driven hard (high revs - lots of heat generation).

    Again, I'll defer to the experts on the board if I miscommunicated.


  9. #9
    Originally posted by Lee
    I believe a higher number was a colder plug.
    Hi Lee,

    I think for Bosch, the higher the number, the hotter the plug. For NGK, the opposite is true.


  10. #10
    I noted that a lower number is a colder plug (therefore a higher number is a hotter plug) with the current numbering system, but I'm still pretty sure their older system was the other way round. For example, a 235 was colder than a 225.

    It may be moot with current plugs, but if anyone has older ones laying around, we should be sure. ANyone have a conversion between the old numbering system and new?


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