Getting a 606 T head from UK for 606T build. Had the intake & exhaust valves, pre combustion chambers & balls sent over to be cleaned up & reconditioned while waiting for head to get here.

They arrived and PC & balls are in great condition, the intake (I believe intake) valves are in really great condition, the exhaust valves have little pitting on top face, probably cleaned up.

But the intake & exhaust stems are two different sizes/diameters.
Intake roughly 7mm & exhaust roughly 6 mm. Not sure exactly where should measure stems.

Vaguely remember reading about 6mm smaller valve stems on few versions instead of 7mm.

What should the intake & exhaust valve stem diameters be for later OM606?
The engine is to be completely rebuilt to new & better specs so definitely want the larger diameter exhaust valves with the 7mm (I think) stems.

The head will be rebuilt with new valve guides, seats & rebuilt/reconditioned valves.

When rebuilding the head can a 6mm valve head be rebuilt with 7mm valves, when putting in new guides & seats?

Sorry for such long post! :-/ Figured might oughta explain situation. Lol

Cheers, Allen

OK, on pre 96 engines, the exhaust valve and intake valve stems were 6mm, from 96 on, they all got 7mm stem sodium filled exhaust valves. You can change the guides out. I recommend it highly, getting 6mm exhaust valves seems to be neigh impossible these days. I've not seen any wear on the chilled cast iron guides. They are hard as hell. Usually just the seats need dressing.