About two months ago my engine caught fire (top of it). I have been gathering pieces and am taking off all the burnt stuff and replacing with good stuff. I was in the process of replacing the valve covers and noticed this. This is a pic of my rear head, please see the middle cyl rockers. Looks like the middle cyl is heating up more then the outer ones. The front head doesn't have this problem. I did plug the LIM coolant holes about 6-7 months ago, but don't see that causing the off color. Opinions would be appreciated.
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