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Stupid Sparkplug Question

Discussion in 'The Hokey Ass Message Board' started by 37hotrod, Jun 26, 2007.

  1. OK, stupid question time. I went to change the plugs yesterday and ended up getting plugs that were one range colder, since they discontinued the ones I was using. I asked what the gap should be, and the counter guy guessed and said 45, because my car wasn't in the computer. I thought that sounded excessive, since the old plugs were around 38, so I went with 40. Now the problem, the car went from nice and snappy, to fat and lazy. The motor is a high compression SBC, with an HEI distributor. Do I need to get hotter plugs, or is my gap incorrect? Chime in with opinions.
  2. noboD
    Joined: Jan 29, 2004
    Posts: 6,161


    Colder range would be for a high performance engine, hotter would be for an oil burner. Sounds like you went the right way. Are you sure the timing is right?
  3. I didn't change the timing at all. I only changed the plugs. Would having the gap set wrong make that big a difference?
  4. Juggalo56
    Joined: Dec 10, 2006
    Posts: 79


    with an HEI your gap is usually around 50 to 55. atleast thats what ive always been told and what i always run.

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  5. revkev6
    Joined: Jun 13, 2006
    Posts: 3,160

    from ma

    how much compression? the higher compression the smaller the gap.
  6. Compression is supposed to be over 10:1, more like 11:1. It seems strange that the old plugs were at such a small gap then.
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 37,095


    what are the numbers on the old and new plugs?

    HEI will fire a gap up to .080" on a stock smog motor, most of them were gapped from .045" to .060".

    close them up a bit and see what happens. My guess is there's something else wrong besides plug gap.
  8. Old plugs AC R46TS. New plugs Champion RV17YC.
  9. ol fueler
    Joined: Oct 6, 2005
    Posts: 935

    ol fueler

    A good share of your problem might just be simply Champion.
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 37,095


    I dont know....

    my old AC book says those numbers interchange.
  11. 302GMC
    Joined: Dec 15, 2005
    Posts: 4,517

    from Idaho

    The key word here is Champion. Trade them for some spark plugs.
  12. Von Rigg Fink
    Joined: Jun 11, 2007
    Posts: 13,431

    Von Rigg Fink
    from Garage

    running accell shorties due to header clearence issues but i gaped at 35thousands SBC 1968 300H.P. motor 9:1 comp..Hei
  13. deucemanab
    Joined: Apr 19, 2006
    Posts: 238


    I Have Run Champion Rj12yc In My 283 For Years. What Type Of Plug Wires Are You You Have Any Spark Tester? Deucemanab
  14. Rich Rogers
    Joined: Apr 8, 2006
    Posts: 2,019

    Rich Rogers

    I bet that's your problem, I have all I can do to make myself put Champs in my lawnmower.R46TS should NOT be a hard plug to replace. Go back and have them check to see if that number has been superceded to a new number. If not, go with NGK or Autolite.God I hate Champion plugs just never had any luck with em
  15. 61 chevy
    Joined: Apr 11, 2007
    Posts: 892

    61 chevy

    i got to ask, did you mis cross a plug wire?:eek:
  16. Max Grody
    Joined: Dec 15, 2005
    Posts: 94

    Max Grody
    from Ky

    This is kinda OT, but way back when I had a stock '57 Pontiac 347 with a standard single point distributor. Ran like a scalded dog and would burn the rear tires off if I really got on it. Did a tuneup and found the plugs were pretty well burned up and had about .60 gap. Put in new AC plugs (same part number as originals) gapped to specs and it was sluggish and seemed like it had lost half it's power. Don't remember what the specified gap was, but it was a lot less than .60, I'm thinking it was about .35. Pulled the plugs out and re-gapped to .60 and it again ran like a scalded dog. Thinking back, I'm amazed the old technology distributor/coil had enough oomph to jump that much gap.
  17. Sniper
    Joined: Dec 26, 2006
    Posts: 75


    Not so sure there is much of a difference between AC Delco and Champion plugs. The "AC" in AC Delco stands for Albert Champion. He was a Frenchman that hooked up with Buick in the early 1900's and that whole bunch is still tied together. Think you'll find the plugs come down the same assembly line, just like a lot of different brands of oil, and oil filters etc. Go ahead, look it up!!
  18. I've been using Champion's for over 45 years, and I've never had any problems with them.
    I don't think there any better or worse than the other makes out there.
    I'd look somewhere else, like the ignition wires.
  19. Flatbush
    Joined: May 23, 2006
    Posts: 47


    Points distrbutors with stock coil set at 35 thou. Hei 45 to 60 thou. Check vacuum advance and and connections at coil. Interesting post, try re- gapping and report back to us


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