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355 Spark Plugs

Discussion in 'Technical Q&A' started by mpodgor, Jan 25, 2008.

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  1. mpodgor

    mpodgor Formula Junior

    Aug 15, 2005
    661
    San Mateo, Ca.
    Full Name:
    Michael J Podgorski
    #1 mpodgor, Jan 25, 2008
    I was wondering how big a deal it is to replace the plugs? This isn't the old V8 I am used to working on. Also, I want to put the best plugs in there that money can buy. Any ideas out there? I have no doubt there is much debate on this. Thanks.
    99 F355 Fiorano #19/100.....................................
     
  2. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    #2 f355spider, Jan 25, 2008
    Not hard. You need new paper gaskets for the covers on the valve covers you remove. Might not be a bad idea to replace the foam block at the end of the cover too. Daniel at Ricambi has these parts.

    The oem plug was the NGK PMR7A plug, but has changed to the NGK PMR8A. These are platinum plugs. There are some NGK Iridium plugs that physically fit, but do not have a long enough nose projection. The only other plug that crosses over is one listed in the Denso catalogs. It is an Iridium plug part number IU22. I don't know of anyone using them, and not sure if the nose projection is correct, but Denso claims compatibility. I just checked and that Denso plug also crosses over to the NGK Iridiums that have the too short nose projection. I would say the safest thing is to use the stock oem NGKs.

    I did run the NGK Iridiums and they were fine, but here is a picture to show you the difference:
    http://www.ferrarichat.com/forum/showpost.php?p=137390425&postcount=41

    How old are the plugs? What mileage?
     
  3. mpodgor

    mpodgor Formula Junior

    Aug 15, 2005
    661
    San Mateo, Ca.
    Full Name:
    Michael J Podgorski
    #3 mpodgor, Jan 25, 2008
    I had them changed at the 15K service. So only about 4k on them. Just wanting to get better performance. And also to examine them to see how check the air/fuel mixure and burn. Thanks for the info.
     
  4. f355spider

    f355spider F1 World Champ
    Owner Rossa Subscribed

    May 29, 2001
    18,055
    USA
    #4 f355spider, Jan 25, 2008
    Not much to be gained, unless one is fouled. If your plug wires are original, it would be good preventive maintenance to replace them. There is no upgrade here either, as the wires fit within the tight confines of the valve covers. They get baked in the valve covers and you can develop a miss or fouled plug. But you can get a new wire set that is 1/4 the cost of factory oem wires at www.kingsborne.com $250 plus shipping. They are 7mm like the oem and use the exact same Beru connectors at each end. The plug end connectors are a upgraded Beru part with four seals instead of the original single seal. These look identical to the factory wires, since they are using the same parts. The only difference I could find was the wire did not have the printed "Beru" on them like the originals, but I believe they use Beru wire too. You can ask them.
     
  5. No Doubt

    No Doubt Seven Time F1 World Champ

    May 21, 2005
    72,740
    Vegas+Alabama
    Full Name:
    Mr. Sideways
    #5 No Doubt, Jan 25, 2008

    That's always a good idea.

    For best results at reading your spark plugs for A/F mixture and timing advance, be sure to make one hard run (up a hill, preferably), and then shut off the engine immediately when you are stopped.

    In this manner you are more easily able to see the performance characteristics of the spark plugs, which can differ markedly from the idle and mid-throttle air/fuel and timing advance settings.

    See the spark plug link in my signature below.
     

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