Best sparkplug for 250 outside plug motor? | FerrariChat
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Best sparkplug for 250 outside plug motor?

Discussion in 'Vintage (thru 365 GTC4)' started by AndruetBiche, Mar 16, 2015.

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  1. AndruetBiche

    AndruetBiche Formula Junior

    Oct 7, 2006
    427
    #1 AndruetBiche, Mar 16, 2015
    Putting my car back on the road after a prolonged restoration. It's an outside plug 1961 128F with 9.4 comp, later bigger valves, split header, street SWB exhaust/SNAPS, hood scoop. Stock points (not electronic conversion)
    I drive in a large city and frequently sit in stop and go traffic. I read earlier about issues with projected NGK BP5ES or BP6ES with piston interference for 250s. I have a set of B5ES but would switch to a 6 if I plan on country/track use - what do you think?
     
  2. Smiles

    Smiles F1 World Champ
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    Nov 20, 2003
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    Matt F
    #2 Smiles, Mar 16, 2015
    I think you're on the right track.

    I used NGK BPR6ES plugs for my 4 litre 209 engined 330 2+2. But I think the heat range was right, and the plug never let me down.

    Start there and experiment.

    Good luck!

    Matt
     
  3. Bob Zambelli

    Bob Zambelli F1 Rookie
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    #3 Bob Zambelli, Mar 16, 2015
    I have put many BP5ES in 250s and they're the absolute best plug I've ever used.
    The B5ES also work very well. The main difference is that the BP has a projected tip.

    Bob Z.

    The BP6 are fine for track use.
     
  4. AndruetBiche

    AndruetBiche Formula Junior

    Oct 7, 2006
    427
    #4 AndruetBiche, Mar 16, 2015
    Bob should I try the projected tip version ?
     
  5. DWR46

    DWR46 Formula 3
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    #5 DWR46, Mar 16, 2015
    For a outside plug 250, use B6ES. The plugs do not hit the pistons, projected tip plugs can hit the outside wall of the spark plug well as they are screwed into the head, thus closing down the gap. This is most common on cars with chassis numbers in the 3000-6000 range. 330's are not affected by this issue, and not all 250 outside plug engines are either, just a series of cylinder heads that had some "core shift" when they were cast.
     
  6. John Vardanian

    John Vardanian F1 Rookie

    Jul 1, 2004
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    #6 John Vardanian, Mar 16, 2015
    My car was in the range that Dyke mentioned and sure enough, one of the plugs ended up with a collapsed electrode upon installation. After driving it a few miles like that intermittent backfire made me wise up to it.

    john
     
  7. Ed Niles

    Ed Niles Formula 3
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    #7 Ed Niles, Mar 17, 2015
    Just remember to "double-washer" them.
     
  8. AndruetBiche

    AndruetBiche Formula Junior

    Oct 7, 2006
    427
    #8 AndruetBiche, Mar 17, 2015
    Double washer the non projected as well?
     
  9. DWR46

    DWR46 Formula 3
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    #9 DWR46, Mar 17, 2015
    No, no need to double washer the B6ES plugs. They clear the walls of the plug well. Ed is correct, in that in the past, people could sometimes make projected tip plugs work in these engines by adding a second washer to not let the plug go as deep into the well and sometimes not hitting the wall.
     
  10. AndruetBiche

    AndruetBiche Formula Junior

    Oct 7, 2006
    427
    #10 AndruetBiche, Mar 19, 2015
    Thanks for the tips!
     

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