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Senior Member
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1,418 Posts
Discussion Starter #1
Three out of 8 look like there were dipped in acid. The center rod is totaly gone in all three, the porcelain is all ate up. The other 5 plugs look like new. The compression is good in all cylinders (155 +/-5. 1100 miles on plugs. Timing set at 12 degrees at idle, 32 total above 2500 rpm. I don't have a realy good camera so this is the best I can do. These plugs are AC PR5LS

So WTF!

 

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Premium Member
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9,134 Posts
Hi Larry,
I would go down in heat range, fuel mixture (to lean) and double check your timing. Detonation does this. As I remember you have new forged pistons and this might be the same problem as before that caused your pistons to break.
Mike Forte
 

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Junior Charter Member
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1,991 Posts
Larry,

How you ever measured your Air/Fuel Ratio with a wideband 0²? Might be interesting to say what your curve is throught the RPM range.

By the way, did you have to do any machine work when you replaced the pistons? Please tell me you found a machine shop somewhere here!

Lukas
 
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