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Message: <blockquote data-quote="96blak54" data-source="post: 1583518" data-attributes="member: 14727">With the amount of head work Ive done on the modular heads, the 2v heads clean up good from a good running 4.6l. NPI or PI heads....it dont matter, either style the valves and seats clean up good with hand lapping. I cant say that about the 5.4l pi heads. For some reason the 5.4l pi heads exhaust valve seat and valve would be pitted to the point id have to cut the seat and grind the valve, then lapping......always lap the valves. My best guess is low octane, low rpm, high miles..... As for the valve guides for either style head 4.6l or 5.4l, I have yet found a valve guide that falls within "suggested tolerance". Typically over suggested by .001". And this is from good running engines with well over 100K miles. Valve stems micrometer out perfect for the full length, but the valve guide is typically over for the full length but consistent full length. Im checking them cold and not hot. Heads being hot, the valve guides probably tighten up a tad and the hot valve stem definitely swells a littleA small investment in tools at the parts store and some adventurous hands on, you could do this work yourself. Itll open up a great hobby for you too.</blockquote>