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Flathead Sparkplugs - What are you using?

Discussion in 'The Hokey Ass Message Board' started by Flatheaded, Apr 3, 2008.

  1. Flatheaded
    Joined: May 17, 2005
    Posts: 338

    Flatheaded
    Member
    from Nordakoda

    I am running an Autolite 216 in my flathead and am having trouble once in a while with fouled plugs. Would it help to switch to a hotter plug? Was just curious what others are running whether it be Champion, NGK, Autolite, etc. Don't know which is best. Any info would be appreciated.
     
  2. Petejoe
    Joined: Nov 27, 2002
    Posts: 10,262

    Petejoe
    ALLIANCE MEMBER
    from Zoar, Ohio

    I had the same problem ..NGK's work great.
     
  3. Mr 42
    Joined: Mar 27, 2003
    Posts: 1,207

    Mr 42
    Member
    from Sweden

    Champion H10c, no problem at all.
     
  4. banjorear
    Joined: Jul 30, 2004
    Posts: 3,774

    banjorear
    Member

    What number NGK's are you running? Does anyone know if they have an extended reach plug?
     
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  5. I run H10C in my fresh flathead and H12's in my somewhat tired one. It made a BIG difference; I was screwing new ones in there every few weeks but have had the 12's in it for a few years now.​
     
  6. i also run autolite 216 in my flat head,havent had a problem yet,but
    i would also like to know what # ngk plugs to run
     
  7. Digger_Dave
    Joined: Apr 10, 2001
    Posts: 2,514

    Digger_Dave
    Member

    I run NGK B6L plugs. They are extended reach.
    If they foul a bit, take them up a heat range.
     
  8. Pete1
    Joined: Aug 23, 2004
    Posts: 1,679

    Pete1
    Member
    from Wa.

    Autolite 295 on gas.
    Autolite 303 on alcohol.
     
  9. cuznbrucie
    Joined: May 1, 2005
    Posts: 2,567

    cuznbrucie
    Member

    NGK B6L.................best I've used out of all of them for flatheads.....

    CB
     
  10. Lucky_mtl
    Joined: Dec 27, 2003
    Posts: 52

    Lucky_mtl
    Member
    from Montreal

  11. alchemy
    Joined: Sep 27, 2002
    Posts: 14,708

    alchemy
    ALLIANCE MEMBER

    I tried these, until the valves flattened them. They do have a longer reach. If you currently use Champion H10 or H10C, double check clearance if replacing with the NGKs.
     
  12. Straightpipes
    Joined: Jan 25, 2006
    Posts: 1,086

    Straightpipes
    Member

    Those valves like to come up and smack those long plugs especially with high lift cams. Clay them upon assembly for use of different plugs and then you will know. I stick with the h10s myself. They've been running in flatheads forever and why reinvent the wheel.
     
  13. lostn51
    Joined: Jan 24, 2008
    Posts: 1,668

    lostn51
    Member

    you couldnt make me run a NGK in anything but a honda. H10C is what i would run and if you have to have one late at nite because of some disaster to the plug, you can always hit the walmart and get them in the lawnmower section.
     
  14. jetmek
    Joined: Jan 12, 2006
    Posts: 1,847

    jetmek
    Member

    motorcraft a7c is comparable to h10's but are slightly shorter for extra clearance over valve
     
  15. Flatheaded
    Joined: May 17, 2005
    Posts: 338

    Flatheaded
    Member
    from Nordakoda

    Thanks to all for the info. I'm off to the parts store in the morning.
     
  16. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    What he said. Never had a fouling problem,but had to do away with metal wire looms I used to run with the hot inginion , it would glow at night.
     
  17. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 3,918

    Automotive Stud
    Member

    I hear champion plugs are junk anymore. I have a set of autolites on the shelf but I haven't used them. I'm running NGK in mine for a few years now with no problems.
     
  18. WHAT # NGK DO YOU USE??
     
  19. Digger_Dave
    Joined: Apr 10, 2001
    Posts: 2,514

    Digger_Dave
    Member

    The problem with ANY long reach plug;
    is it being used in a after market head with a high lift cam??
    (plug depth varies all over the map with after market heads!)
    If the valve to plug electrode clearance is TOO close, ANY plug is going to get "mashed."

    The clearance needs to be checked before using them. (by "claying" them)
    If they are too close, extra thick gaskets ** on the plugs can cure the problem.

    ** The extra thick gaskets also allow the plugs to be "indexed." (electrode facing the intake valve)
     
  20. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 3,918

    Automotive Stud
    Member

    Same as the rest, B6L
     
  21. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 3,918

    Automotive Stud
    Member

    That's what I used to think. Then I decided to use what works best. :D
     

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