Ok, with the heads taken down and cleaned of carbon (or at least as much as I could scrape and wash out) time to start the inspection process.
First, the head needs to be checked for warpage. You need a good machinists ruler/straight tedge to do this (one of the I-beam types) Lay it across the machined surfaces and use feeler gauges to measure any gaps. The critical one is the head-to-block deck surface, since this will provide the clamping force on the head gasket to seal it up. These check out pretty well, so we'll keep on trucking on the rebuild.
If the head is warped, you have two choices:
1.) Rebuilt or New replacement heads. Considering the price of the heads, this is a viable option. Same will hold true if any of the valves or guides are screwed up...it'* the law of diminishing returns in action. The cost to fix the head can soon exceed the cost to replace them. (There are a few motors in the world that are so rare as to warrant doing a lot of work to refurbish the original parts, since the replacements are made of pure "Unobtainium"...the Series II 3800 is not one of them.)
2.) Resurface the existing heads to square them back up. Note: This has some negative effects as well. Removal of material from the head means the chamber volume of the heads is reduced, also, the intake manifold may also need surfaced too..since the heads will sit a little lower and move the intake manifold flanges down closer to the block deck.
Another important little tidbit involves the block deck surface. The machine shop checked that for me and did not have to resurface the deck. That'* good news to me, the 3800 is NOT a "zero-deck" motor (as we'll see when we reassemble the block) The pistons extend beyond the block deck into the head gasket area. Any change to the block'* deck would mean either shim head gaskets or machining the pistons down so they don't hit the head.
But we were talking about cylinder heads, so here are a pair of cleaned up valves:
The top valve is the #1 exhaust valve, the bottom one is #1 intake. Note the long silver "scratches" down the stems...they aren't scratches at all, just the reflection of the camera flash on the hard-chrome finish of the valve stem. Each valve is made of two parts. The stem is hard-chromed steel to give it long wear in the guides. The "Valve" is a milder cast steel that has been brazed to the end of the stem. It'* done this way so the mating surface of the valve to the seat can be ground to a good seal.
Cleaning the valves is pretty simple. Soak them in solvent, then scrub the carbon off. When they are clean, check the diameter of the valve stem with a micrometer. You are looking for any taper in the stem that would be an indication of wear and allow the valve to rattle against the valve seat. Also, if the motor was starved of oil, you would see a lot of wear down here.
Last, check the width of the seat area on the valve. If it gets too wide, then the valve needs to be replaced, also if any ridged have formed on either the lip of the valve or it'* seat in the head, both will need to be remachined or replaced.
With the valves cleaned up, the valve guides in the cylinder head need to be cleaned out. A 30caliber rifle bore brush (phospour bronze, not steel) is the perfect fit to scrub out the guides. You can check the diameter of the guides with a set of pin gauges, however I found this to usually be a waste of time. If you didn't find any damage on the valve stems, then it'* highly unlikely there is any problem with the guides. If you do have a problem with a valve stem, then the only solutions are to ream the guide larger and use an oversize valve..or ream the guide WAY oversize and install a sleeve to restore the original bore diameter to the guide.
With the valves ready for reassembly, the seats need to be lapped using the actual valve that will ride on it. Lapping compund is like liquid sandpaper. It has a fine grit (around 600) and a little smear of it around the lip of the valve is all it takes. Apply a little pressure to the valve to force it against the seat and spin it in the bore. That will polish both the valve and seat together, giving you a nice tight seal when the valve is closed. Clean it off with solvent when you are done.
Here'* #1 cylinder valves ready to be lapped into the seats: