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Engine Mechanical TopicsDiscussion for motor builds, cams, head work, stripped bolts and other engine related issues. The good and the bad. If it goes round and around or up and down, post it here.
I agree with everything others have said. You need a valve job. If you want to prove it out further, test the valves ability to seal against the seat. Reassemble the heads and position each port one at at time so they're facing up.. Pour gasoline into each the port and watch for gas to run out of the valve/seat .
Cheapest way might be get those pitted valves refaced in a valve grinding machine at a machine shop. The seats look passable, although a little wide but still useable.
Take the heads and valves in and get the machine shop guys to look at it in the flesh and give you their opinion. Take them the factory manual about how deep you can cut those seats vs valve stem stick-out too. And see what they think about the valve to guide clearance/wear. They will need the factory manual specs for that too.
"Resurfacing" the valves ... Remember that the more grinding that is done on the valve the more material is being removed ... This leaves much less material at the outer edge of the valve ... Ever hear of a "burned valve" ... That is what can / will happen if you get too aggressive
The pitting on the valve shown looks to be pretty deep and if reground may be too much off the valve face.
Just my opinion, I would take it to someone that works on heads and get their expert analysis.
Hard to really know unless the valve(s) were in hand and not looking at an internet picture.
Didn't know your micrometer eyeball was that good..
As stated previously, check the stems and guides for wear, the valve end for pitting. Grind the valve and check how much margin was left.. Not enough replace the valves. I used to own a Snap on valve and seat grinder. Did a lot of valve jobs with them mostly HD and Honda. Now, I'll simply replace the valves since I too lazy to send them out.. If replacing the valves, I'd recut the seats. If replacing the guides, seats will need recut..