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).
Engine's design and condition after a 3000-mile test, including details on the cylinder head.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan069 | |
| Date | 20th December 1927 guessed | |
| contd :- -2- An overhead camshaft, driving by 'silent' chain, is used; the cams being of the mushroom type, rubbing directly on the valve stem caps. Dual battery ignition is used; the system is by Delco, is a six-volt system and employs only one distributor and two pairs of low tension contacts worked off one cam. There is nothing unorthodox or striking about the engine; it is designed more for ease of production than for refinement of running consistent with efficiency. On dismantling the engine after a little over 3000 miles running, it was found necessary to regrind the valve seatings, which had 'stepped' badly and were also excessively pitted, one piston ring was found broken, (evidently broken during erection) and the bearing metal in two big ends was found to be cracked, not a very good record for a supposed 'high grade' car. There follows a more detailed of the various sections of the engine. CYLINDER HEAD. The cyl. head is one casting in cast iron fastened to the crankcase by means of 18 7/16" dia. studs. The exhaust and inlet ports are identical in size and shape (1.450" dia.) - they are exceptionally straight and give an unimpeded gas passage. There are eight inlet and eight exhaust ports. The inlet ports being on the near side and the exhaust ports on the off side of the head. Two sparking plugs per cyl. are provided and are situated one on each side of the head. contd :- | ||