Rolls-Royce Archives
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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).
Performance graph comparing different valve lift timings and settings against engine RPM.

Identifier  ExFiles\Box 13\2\  02-page138
Date  9th August 1931
  
COMPARISON OF VALVE LIFT 114° SHAFT
RM.{William Robotham - Chief Engineer} P.19.
LARGE VALVE HEAD. 4.78 C/R 2.0" VALVE THROAT
114° CAMSHAFT E.82448 OPEN EXHAUST
TIMING .013 C.L.C.E.
TWIN CARBS 14 THROATS
I.O. 3° B.T.C. E.O. 54° B.B.C.
I.C. 58.1° P.B.C. E.C. 12° P.T.C.
HIGH LIFT TIMING .013 C.L.C.E.
I.O. 2.25° B.T.C. E.O. 54° B.B.C.
I.C. 60.3° P.T.C. E.C. 19° P.T.C.
VALVE LIFT .525
VALVE LIFT .470
CLAUDEL HIGH & LOW LIFT
B.H.P.
B.M.E.P. LBS/SQ'
INDUCTION PIPE DEPN
R.P.M.
HEAD MACHINED TO GIVE A MINIMUM OF .2 CLEARANCE ROUND THE INLET VALVE HEAD.
SIMILAR CURVES TAKEN WITH CLAUDEL
CARB. SHEWED NO INCREASE IN TOP M.E.P. BUT A SLIGHT DROP IN LOW SPEED M.E.P./2 LBS/SQ'
INDUCTION DEPN ROSE .35" HG WITH HIGH LIFT ROCKERS.
  
  


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