<VV> valve guides

[Michael Kovacs]

 I'm preparing to replace the valve guides (burns oil) in a 140. I know all the guides were the same from the factory. I want to know why over sized are used .001, .002, .005 etc. Does this mean that the head has to be reamed to fit the guide?

 Or does this relate to over sized valve stems?  Either way, steel or bronze and is there a recommendation for a vendors number.

 Engine is for a show car that will seldom be pushed beyond 5,000 rpm under normal circumstances. Balanced pistons and con rods etc.

  I'll do some research in the overhaul manuals in the mean time.