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Discussion Starter · #1 · (Edited)
I just switched out my NGK TR55 plugs with 19k miles on them for Autolite 764. Both are copper and I as soon as I was done I could tell a difference in both throttle response and low end power. I'm just assuming it is because the NGKs had that many miles on them.

Here's my question: The plugs were fairly white but not completely. White on the side of the "hook" and more black on the top. They weren't blistered and had no deposits on them at all. When I dynoed in November my a/f was 12:1 and this was before the Densecharger. I don't think that it could have leaned me out that much. I've always heard that "normal" was brown to grayish-tan color and slight electrode wear. There isn't any brownish color on them at all. I just checked the gap and they all are around 0.058". I gapped the new plugs to 0.052". Do you guys think I may be running lean or was it the larger gap?

I don't have that much experience reading plugs, hence my question. Just want to make sure I'm not risking anything.


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