Dropped my Bp4w head off with a machine shop who only does cylinder heads. Valve job, resurface and new guides. I can tell the guides were replaced. But why the F&*k did they knurl them? Do some shops do this to new guides for oil retention?

 

Yes, pretty normal oil retention grooves.

 

any idea if this reduces the life of the guide much ? Goal is to get 50k miles out of the forged motor im building before needing a rebuild