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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).
Page detailing engine specifications, a comparison of valve areas, and a description of the valve gear mechanism.

Identifier  ExFiles\Box 137\4\  scan0012
Date  1st June 1929 guessed
  
contd :- -2-

Choke dia 1.187"
Induction pipe uptake above choke 1.425"
Induction ports on block 1.425"
Inlet valve head dia. 1.725"
Exhaust " " " 1.600"
Valve lift .312
Valve stem dia. .340
Length conn. rod 10 7/16"
Ratio l/r 4.17*1

Valve areas at full lift :

Engine. INLET. EXHAUST.

sq.in. sq"/litre. sq.ins. sq"/litre.

G.1V (3.00" bore) 1.44 2.77 1.335 2.56
Chrysler. 1.69 2.49 1.566 2.30
S.S. 2.56 2.00 2.29 1.79

For unit weights see at end of report.

VALVE GEAR :

Side valves are operated by mushroom tappets,
and almost tangent-flanked cams. The tappets have tubular mild
steel stems and welded in chilled cast iron heads. These are
slightly eccentric from the cam, and have taken on a very fine
finish where the cam rubs. The cast iron head on one tappet
has broken inside the m.s. tube, and has been replaced.

The total weight of one valve plus tappet, collap
cotter, and 1/3 spring is 10.37 ozs. contd :-
  
  


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