Philip Dayson says:

> Mr. Stephenson says "variation of valve lift anywhere between 0.020"
> and 0.075" has no significant effect, so that it would not appear to
> be worth while to lavish time and care on determining what clearance
> to use, or even on effecting uniformity. ... Anywhere between 0.035"
> and 0.050" would be likely to be satisfactory."

> This statement is absolutely _contrary_ to the opinion of most
> restorers. Why the difference??  I have no reason to doubt the
> accuracy of Mr. Stephenson's work.  Is there a factor other than
> hammer velocity at work? Any comments?

I'm not a restorer but I am sure Mr. Stephenson's assertion would burst
a few blood vessels amongst those I know.  The whole point of accurate
valve settings is not loudness but loudness balanced against rapidity of
action.  There's a point at which reducing the travel begins to choke the
instrument in rapid repetition and you go for a setting just above that.

Hugh Stephenson contributes long articles of much this same character to
the PPG Bulletin.  Amongst the restorers I know, they are treated with
tolerant skepticism.  The proof is in the pudding.

Dan Wilson