The performance, issues, and modifications of an S.U. Thermostarter Carburettor.
| Identifier | ExFiles\Box 121\4\ scan0154 | |
| Date | 29th December 1937 | |
| To Rm {William Robotham - Chief Engineer} /Swdl. {Len H. Swindell} c. to Rm {William Robotham - Chief Engineer} /FD. {Frank Dodd - Bodies} 1487 Rm {William Robotham - Chief Engineer} /JBD. {John B. Dixon - Fuel Systems} 1/JH.29.12.37. The S.U. Thermostarter Carburettor. This was fitted to an induction pipe by the S.U. Company and fitted to 1.B.1V on 20.2.37. The auxiliary induction pipe underneath the main pipe ran very close to the plug terminals and was inclined to make the high tension current jump across, added to which it was extremely difficult to remove the plugs. The thermostatic contact was fitted in the top water pipe to the radiator. When first supplied we had trouble with the solenoid operating the valve but this was found to be due to a faulty solenoid which was replaced by the S.U. Company. After this we never had any difficulty starting even when the car was left out all night but there was never a really hard frost. At first we found the auxiliary carburettor did not give quite a rich enough mixture on pick-up and was obliged to fit a needle with a steeper taper than that originally supplied. The car covered 7,768 miles with the thermostarter and we had no complaints of failure to start and for the bulk of the mileage the car was used for transport to Shardlow. The only objections raised were that while the starter carburettor was in operation there was a loud hissing noise and secondly that it caused the engine to fast idle at from 1,000 - 1,200 r.p.m. The scheme was removed when a thermostat was fitted to the cooling system. If the scheme is tried again the thermostatic contact will have to be fitted in the cylinder head or bypass pipe from the thermostat in the cooling system provided that the latter is not closed when the thermostat valve opens to the radiator. The S.U. Co. recommend fitting the thermostatic contact in a pocket cast in the cylinder head. Rm {William Robotham - Chief Engineer} /J.B.Dixon. | ||
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).