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 engine dimensions for various American car models.
| Identifier | ExFiles\Box 82\5\ scan0133 | |
| Date | 19th May 1937 guessed | |
| CAR | INLET THROAT DIA. | DIST. BET. VALVE THROATS | EXHAUST THROAT DIA. | MIN. DISTANCE BETWEEN BORES. | VALVE CENTRES TO CYL. BORE. | OVER ALL LENGTH OF CYL. BLOCK. | BIG END DIA & WIDTH. 8 BUICK SERIES 40 3 3/16" BORE | 1 3/8 | | 1 1/4 | 1/2" | | 31 1/4" | OLDSMOBILE 8 CYL. 3 3/8 | 1 3/8 | 1/2 | 1 1/4 | 11/16 | 1 3/16" | 32 7/8 | DODGE 3 1/4" BORE. | 1 5/16 | | 1 9/32 | 5/16 | 1 1/4 | 23 3/8 | 2.0 & 1.00 TERRAPLANE 3" BORE. | 1 1/4 | 7/32 | 1 3/16 | 3/16 | 1 1/8 | 21 1/8 | FORD 80 | 1.3 | | 1.3 | | | | 2.2 & 13/16 PLYMOUTH. | 1 5/16 | | 1.3 | | | | 2.0 & 1.0 CHEVROLET | 1 5/16 | | 1 1/8 | | | | 2.25 & 1.25 CHRYSLER 6 3 3/8 BORE. | 1 7/16 | 5/16 | 1 5/16 | 5/16 | | 25 1/2" | OLDS. 6 CYL. 3 7/16" BORE. | 1 11/32 | 1/2" | 1 7/32 | 23/32 | 1 1/8" | 27" | ALL EXCEPT BUICK SIDE VALVE ENGINES. | ||