I have seen machine shops tear down and rebuild heads. I am no expert at all about all the inner workings of what the machinist's do. But that looks like a #5 guide problem/mark? Some machinist here will hopefully chime in and tell me I am full of shit, or just any member that feels like saying it, and you are ok.
I would say though that if you put new plugs in and they get fouled in 7 minutes, I would not lean toward those valve guides and seals. I believe it is a fuel foul and you have another problem. Plus, in your first pics, #5 plug was not fouled. By the way, in the most recent plugs pics, how the hell did the #6 plug lose the ground tip? It's gone. Did you say something about that somewhere else in the thread and I missed that?
I would say though that if you put new plugs in and they get fouled in 7 minutes, I would not lean toward those valve guides and seals. I believe it is a fuel foul and you have another problem. Plus, in your first pics, #5 plug was not fouled. By the way, in the most recent plugs pics, how the hell did the #6 plug lose the ground tip? It's gone. Did you say something about that somewhere else in the thread and I missed that?
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