The third wrench is for holding the "cap" that covers the valve spring. You don't always need this as it may not turn whilst you are adjusting...

I've been informed (here) that it is best to go for the larger clearance during an adjustment as the valves tend to tighten with use.

Check out post #25 and onwards on

http://www.peachparts.com/shopforum/showthread.php?t=276144&page=2

Have a look on YouTube for some videos for a how to - a moving picture says 10,000 words!

__________________
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!