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).
Comparison table of silent tappet specifications for various car models.
| Identifier | ExFiles\Box 106\5\ scan0121 | |
| Date | 29th November 1933 | |
| FILES. X5060 29.11.33. SILENT TAPPET COMPARISONS. Spring Load Only (Cadillac & Pierce Arrow, spring load taken at the same figure as J.III) x5060 | | Eccentric | Eccentric | Pierce Arrow | Phantom | | Cadillac. 47: 1 | J.III. 267: 1 | Direct Acting. | Direct Acting | Dia. of Plunger. | .6234 | .5245 | .4995 ø | .4995 | Clearance between Plunger and Case. | .0016 | .00075 | .002 | .0005 | Clearance Area A.{Mr Adams} sq.in. | .00313 | .00120 | .00314 | .00079 | Effective length of Plunger. | .932 | .650 | .750 | .545 | Max. load on Plunger (lbs.) | 58.8 | 33.45 | 125 | 149 | Max. Press of oil beneath plunger (P.lbs/sq.in) | 192.8 | 155 | 637 | 760 | (Max) Leakage Factor PA{Mr Paterson}/L. | .647 | .286 | 2.67 | 1.103 | Lift of Ball Valve. | | | .015 | .005 ø Plunger return spring : Free length = .95 - Load - O Fully compressed = .527 - " - 7 lbs. Taper Spring (Rectangular Section Wire. Inner Dia. (Small .467 Total 5 coils (Depth .080 Thickness .040 (Large .600 | ||