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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Resolving an engine knock by adjusting valve clearances.

Identifier  ExFiles\Box 66a\2\  scan0017
Date  30th March 1926 guessed
  
contd :- -4-

We refitted the cyl. block and on running the engine
we were satisfied that we had finally overcome the knock. We
made certain that the valve clearance was correct i.e. .008"
and after running the engine for some considerable time, the
valves remained quiet.

We should like to draw attention to the clearances in
the valve guides. The inlet calls for .002" to .004". The
exhaust calls for .004" to .006". We are of the opinion that
it would be possible to run without seizing with a clearance of
.003" in both guides which would be one more favour for quietness
of the valve mechanism.

We have taken the matter up with the D.O. re.
excessive clearance of the bottom washer of the valve, and we are
having the limits made finer, and with the new bottom washer
this should be a good fit.

Hs{Lord Ernest Hives - Chair}/G.W.Hancock.
  
  


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