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).
Development report on the testing of Spectre test units, detailing findings from the first unit's noisy valve mechanism and performance.
| Identifier | ExFiles\Box 4\1\ 01-page242 | |
| Date | 1st February 1935 | |
| COPY FOR FILES. X300 1.2.35. SPECTRECodename for Phantom III DEVELOPMENT. We have up to the present had three SpectreCodename for Phantom III Units for test purposes, Nos. 1, 2 & 3. The first Unit received was No. 1 on 29.6.34. to specification RRC/HSC/EP{G. Eric Platford - Chief Quality Engineer}4.7.34. This Unit was fitted with whitemetal bearings both main and big ends; E.85255 camshaft 114°, and semisplit type pistons E.84545. ---------------------------- The surprising feature of the first run on this unit was the excessively noisy valve mechanism, and to obviate any fault in the self-adjusting tappets these were made as standard tappets with adjustable clearance. It was necessary actually to hold the valves off their seats to obtain quiet operation. Upon checking the cam contours, considerable differences were found at the foot of the cam to that shewn on the LEC, and it was decided to have the camshaft inspected when the engine was dismantled. The self-adjusting tappet mechanism was very unsatisfactory, the white-metal lined eccentrics wedging on the steel shafts and the oil feed to the plungers being unreliable. This unit developed 187 BHP. at 3500 r.p.m. with a maximum MEP of 112 lbs/sq.in. at 1500 r.p.m. Water flows were taken, showing a lower flow and higher temperature rise across the unit than expected. The induction system gives very good distribution. After 25 hours running, including 1 hour endurance at 3500 r.p.m., the unit was returned to RRC. for inspection on 20.7.34, having been on test for 3 weeks. | ||