By rotocap, I'm guessing you mean the cap nut? They are fine. I even switched them to make sure.

No under the valve spring there's a thing that spins (called a rotocap)...

The valve should close up against the seat in the head. If the valve spring is so old that it doesn't compress as much as it should then the valve might not be closed when you are measuring the clearance. If the rotocap is squashed / collapsed then you've got the possibility of a similar problem.

I'm thinking that you've either got one valve higher then the rest or 9 valves lower than they should be!

If you've got one high one then I'm betting you've got a valve seat problem. Not good news...

Some more data for you =>

The valve spring should be about 50mm long when unloaded (I can give you the exact length you should have if you pass on your spring colour codes).

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Thanks all. My conclusion is there will be a pulling of the head in the future. I needed to get it back on the road so I will have to contend with a slightly tight valve for now.

I am most grateful for the help.