10mm

FYI: Don't grind exhaust valves, buy new. Grinding the exhaust valves on most MB engines can cause them to burn up within a few thousand miles if they're sodium-filled. And most are.

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Current:
2021 Charger Scat Pack Widebody "Sinabee"
2018 Durango R/T

Previous:
1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
1999 Chrysler 300M - RIP @ 221k

Sounds like you have a pretty good grasp on things Basil. In the sixties a lot of dealerships and independents did their own valve jobs in house on these heads.If it turns out you need new guides or some of them remember to get the stem guide clearance right. I think you know that you warm up the head and freeze the guides before driving them in as well. Good chance to check your chain guides etc as well. As for timing I guess I would put cam mark on and read bottom pulley and duplicate on assembly. Even on heads I send out I have always inverted them and put some thin liquid in to check for good seal overnight before installing. Just paranoia I suppose.

Not as good a grasp as I would have liked....The timing chain went down the hole. It seems stable enough for now and it made it easier to get the head off. It's now in the dining room and I am about to take off the manifolds while my wife takes a nap. I'm working in the house since it's warmer and the light's better. The dining room has a linoleum floor in case the oil gets past the cardboard. When she wakes up the project will be smaller, cleaner, and portable!
It's still too early to know what lies ahead and I haven't examined it closely, but the exhaust valve in #5 was burned as predicted. And thanks to Arthur and Ellington I have the right gasket set.

I'll keep you posted. Feel free to comment and advise. I am fairly inexperienced but can generally take things apart and remember how to reassemble them.

Basil

Hmmm. It did strike me as odd when I matched up the thrust washer and cam marks, noticing the dist. rotor pointed right at #1 plug wire, that the pointer above the timing marks was pointing at a spot 2/3 of the way to the 10 degree mark left (my left,standing in front, looking at the engine) of the 0/0 degree mark where I expected to see it. does that mean my heads been shaved or the chain's off a tooth or is that normal...?

Timing chain stretch..
It may get closer to TDC w/new head gasket..but if there is any mileage to that engine/chain, I would roll a new one in there after all that work. Those chains did not give the hours of service the new ones do, just by design.
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