massive reconfiguration time again.

So what plug did you have and what plug did you go to. Not the box # the part number on the spark plug itself.
When I got the Stroker motor put together I believe I was using a really hot plug with the insulator sticking way out LOL I showed it to the machine shop and they recommended a much colder plug and I'm going to want to say it was the Autolite 3934 that I've been using.< that may have also been when I brought the heads into have the 202 valves put in and seen a little detonation on the tops of the Pistons. That's the only reason I can think of that I was using it unless I cross-referenced it to the plug that he had told me just to get something cheaper but I don't think so. So I think I bought a few sets of those over the years.
About a few weeks ago when I thought it was time for more tuning and oil and plugs and things I decide to cheap out and cross-reference them to the 4554 witch is a number 8 on the NGK scale. There's no part number on the plug that I can see and I don't have a box for those.
After a few members mentioned going down a number to a hotter plug I called NGK and they recommended the 4091. I'll show a picture of the part number on the box because it's not on the plug either. It just shows a 7 where the others showed an eight.
All I can really give you on the 4091 from the 20 miles I put on them it may have up the idle a little bit and seemed to smooth it just a tad bit and sounded a little bit crispr maybe, but that's real seat-of-the-pants BS.... Could simply be all in my head and what I was hoping for...
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