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F355 spark plugs

Discussion in 'Technical Q&A' started by F355Bob, Apr 19, 2004.

  1. F355Bob

    F355Bob Formula 3

    Did Ferrari recommend a hotter plug for the 95 F355? I seem to foul plugs every year. I always run the car to at least 6-7000 rpm in gears. Someone told me the plugs will foul if you run the car to back out of your garage and shut the engine down without letting the engine get to running temp. Any truth to this?
     
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  3. lib308

    lib308 Rookie

    Jun 20, 2017
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    Alan P. Read
    my 308gtb does not like the recommended plugs.( ngk bp7es ). in fact, some say the bp8es is recommended,
    with the 7's, I can flood one or more cylinders. I would suggest trying one heat range hotter. my 308 runs really
    nice with ngk bp5es plugs. I personally would not bother with exotic metal plugs. they do last longer but part of
    the fun is checking and changing your plugs. and also copper is a better conductor. best wishes, alan.
     
  4. Motob

    Motob Formula 3
    Professional Ferrari Technician

    Nov 11, 2003
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    Brian Brown
    If a modern car with a Bosch Motronic engine management system with lambda feedback (oxygen sensors) is fouling spark plugs, there is something wrong with it.
    You should be able to start and stop the engine multiple times without fouling the plugs. Are they fuel fouled, or oil fouled?
    You don't need to change the heat range of the plugs, you need to fix the issue that is causing the plugs to foul. Do you drive the car (put more than 1,000 miles a year on it). How new is the fuel in the car? Have the original valve guides been replaced?
     
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  5. MerlinTech

    MerlinTech Formula Junior
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    You are correct. I don't remember the plug numbers, but I remember replacing the plugs in every new 1995 355 that came through Ferrari of Atlanta. We could not move one out and shut it off with out killing the plugs. They (factory rep) had us install one step hotter plugs.
    Even with modern technology it happened. It was carb 308 all over again.
    I have had a couple 1995 355 foul plugs over the years as well as they were moved and not warmed up well. I just make sure I warm them when I move them in or out of the shop. Just saves having to replace plugs.
     
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  6. F355Bob

    F355Bob Formula 3


    I still have my car but it now has two computers piggybacked to the stock. The 95s run rich so fuel was removed on low end and I don't have that problem of plug fouling. This summer going to do coil on plug which will give hotter spark which should help also.
     
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  8. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    7,008
    In 94 and 95 for the 2.7 F355s, Ferrari changed the number of sparkplug 3 times.
    Ferrari now recommends the same plug for 2.7s as for 5.2s.
     
  9. Dave rocks

    Dave rocks F1 World Champ
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    I've used NGK PMR8B in 95's. I've not replaced my plugs in the 98 yet (no issues)
     
  10. tbakowsky

    tbakowsky F1 World Champ
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    Next time your plugs are fouled up..post a picture of the plug. My bet is it's oil, and it will most mostly prevalent on #2 and #5 cylinders.
     
  11. Dave rocks

    Dave rocks F1 World Champ
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    I'll also add that I have a plug on my desk taken from my project 95 (not installed by me) and it's NGK PMR7A
     
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  13. Motob

    Motob Formula 3
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    Ferrari recommended PMR8A for the 1995's and PMR7A for the 1996 and later cars. With NGK the higher the number, the colder the plug, so the PMR7A is one heat range hotter and less prone to fouling than the PMR8A. You could probably use the PMR7A in the 1995 with no problems and have less of a fouling issue.
     
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  14. INTMD8

    INTMD8 F1 Veteran
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    I'll be interested to see what plugs are in mine. Haven't been out in 5 years and no issues thus far. (Oct 94 build date)
     
  15. F355Bob

    F355Bob Formula 3

    I use the 7's and have a 94 build date also.
     
  16. Ferraripilot

    Ferraripilot F1 World Champ
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    Fun fact: a Polaris snowmobile, forget which model, uses the same spark plug.
     
  17. f355spider

    f355spider F1 World Champ
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    Crap, I always thought it was the opposite of this...that was what I was told years ago by Daniel at Ricambi. I used the PMR8A (or maybe the B) in my 1997 F355 spider without issue for several years. I had changed to them a few months before a major service at FoS and they had no issue with them, they inspected and reinstalled as they said they looked new.
     
  18. Ricambi America

    Ricambi America F1 World Champ
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    I hope that isn't the information you were provided by us. PMR8B (used to be PMR8A) is used often in the 1994/1995 cars, and PMR7A in the 1996- vehicles. We have specified it this way for as long as I can recall, and have specific service kit configurations for the F355 to accommodate this variation.
     
  19. f355spider

    f355spider F1 World Champ
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    It was from you Daniel in an email exchange eons ago....but it is entirely possible I read your email incorrectly or interpreted it incorrectly. Regardless, my 5.2 Motronic ran perfectly fine with the colder plug and never fouled, they were in the car for about three years and were in it when I sold the car.
     
  20. Cirorsi

    Cirorsi Formula Junior
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    Nov 10, 2016
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    Steven
    I'm changing my plugs out now (PMR7A are in it so that's what I'm going back with) and man it has been a bear getting the insulators out. 1-4 were really tight but 5-8 aren't budging with my specialty tool (recreated Ferrari tool). I ripped part of the rubber edge off #8 as the specialty tool cut into one edge. I tried moving the insulators left/right and gently up/down to get the suction to break but it's not moving. I have some plastic pry bars, will it crush the Kingsborne insulator if I use some leverage underneath while pulling with the specialty tool? I don't know why that side is so tough, I don't see any moisture behind the insulators.
    Anybody have a better idea to get 5-8 off?
     
  21. Dave rocks

    Dave rocks F1 World Champ
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    Steve - are you saying our tool did not work? I'm shocked if so. Those boots can be very hard to get off but our tool usually has no issues.
     
  22. Cirorsi

    Cirorsi Formula Junior
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    Dave, I'm thinking that I may have rocked back and forth too aggressively as I was pulling up, causing it to bite on one side. The tool fits as snugly as it can over the top of the head so I was shocked when it slipped off.
     
  23. INTMD8

    INTMD8 F1 Veteran
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    Did you try to twist it to break it free before pulling?

    (that's what I do with pretty much all plug wires)
     
  24. Cirorsi

    Cirorsi Formula Junior
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    Jim, yeah, I twist before I pull up. Yesterday I warmed up the engine to let the heads expand a little, then I placed a small plastic pry bar under the head as I slowly and steadily pushed / pulled up. They came off without drama from there. I pulled a torn boot off today to take pics (on a cold engine) using the same method and it just as easily came out without further damage to the rubberized side molding. I don't know if Kingsborne is using the same Beru head or are they slightly different? The tool still fits snugly but from now on I'll use the pry bar to assist.
     
  25. yelcab

    yelcab F1 World Champ
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    Kingsborn uses the same Beru connectors but those are not available by themselves. You have to buy the whole set.
     
  26. Dave rocks

    Dave rocks F1 World Champ
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    Sometimes those boots are just crazy tight. I'm guessing the sealing vaines on the boot get stuck to the cylinder head bores which is why Jim suggested twisting first
     
  27. Dave rocks

    Dave rocks F1 World Champ
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  28. johnk...

    johnk... F1 Veteran
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    Jun 11, 2004
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    #25 johnk..., Apr 25, 2018
    Last edited: Apr 25, 2018
    Dave,

    May I suggest a 2nd gen version of the boot tool. The current tool grips the boot only on the sides, as indicated by the red line in the figure to the left. For Gen 2 maybe mod it so it grips the boot over both sides and the end as indicated in the figure to the right. Should work on either type boot.

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