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.
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?
I didn't change the timing at all. I only changed the plugs. Would having the gap set wrong make that big a difference?
with an HEI your gap is usually around 50 to 55. atleast thats what ive always been told and what i always run. dave
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.
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.
running accell shorties due to header clearence issues but i gaped at 35thousands SBC 1968 300H.P. motor 9:1 comp..Hei
I Have Run Champion Rj12yc In My 283 For Years. What Type Of Plug Wires Are You Running.do You Have Any Spark Tester? Deucemanab
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 Go back and have them check to see if that number has been superceded to a new number.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
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.
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!!
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.
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 Bob
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