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How hurt is it? Plug pics, very large!

1195 Views 14 Replies 8 Participants Last post by  Mike Beck
Was out goofing around the other night, things seemed OK. Race a car with very loud exhaust, two races. Nothing too exciting. Drive home I romp on it once and it's pinging like a MO-FO! WTF!? Somehow decided to go for 40° timing. I finally got around to pulling the plugs tonight and crap.. Speckles on most, porcelain eroded off others, rainbow on a couple straps. Here's two samples. What's with the speckles? and what causes the porcelain to erode like that around the positive electrode?

I compression tested it, 145-160 all around. Thinking about borrowing a bore scope. What should I expect to see? You guys think it's hurt?

Pictures not resized smaller for better clarity. Note: I use bronze looking anti-seize, that's not rust. And my drive home was 15-20 miles of in town driving, so the mixture is/was all over the place for the rest of the discoloration.


Porcelain erosion:
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I wouldn't go above 150ish with nitrous. Why the timing problems? What ECM are you using? I have EFI, have done EFI on many, many combos, only one ever gave me problems, it was just the plug wire/ non resistor plug combo...... I run non-resistor plugs all the time, no problem. Those plugs may be too hot. With EFI you can certainly run a nice cold plug and have no problems with them.
NOS327, I have a 383 in the wifes car and with pump gas I can't go above 34 total without the possibilty of rattling it. I can do 36 in good air, but in the heat I can't keep the car below 170 and it will rattle a bit. I just leave it at 34 total all the time.

When I spray it I pull a lot to be safe since I don't put race fuel in it. Have shot it with 150hp with no problem but I pulled 8 degrees from the 34.

Are you running a wet-system or do you fool the Holley to do the fuel and timing?

On pump gas you should run it between 12.0 and 12.5 A/F. Put it on a chassis dyno and try it sometime.
I am only talking about full throttle. At part-throttle run that baby 14.5 to 15.0 A/F, as lean as you can and with as much timing as you can. If you have trouble with tip-in and can't get it right with the accel pump then run it fatter 'till you like it. :)

That's the beauty of EFI, we can do whatever we like with timing and fuel at any rpm and load on the engine.
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