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).
5,000-mile test report on engine unit 14 GIV, detailing performance and issues with the exhaust manifold, valves, and suspension.
| Identifier | ExFiles\Box 5a\2\ 02-page196 | |
| Date | 12th February 1930 | |
| X5840@ To: Us. From S.E.H. Hôtel de France, Châteauroux, Indre. 12/2/30. REPORT ON 14 GIV at 5.000 Miles. ENGINE UNIT N° IV G & C WITH COMPRESSION RATIO 5.257.- The engine, during the 5.000 miles, has maintained its power and good acceleration, up to 60 M.P.H., it has been particularly smooth and free from any periods. At speeds over 60 M.P.H. it is decidedly rough, both on acceleration and retard. Slight detonations became noticeable at approx. 4.200 miles. The detonations were more noticeable when running with the magneto ignition. We have, after every 500 miles, taken a slow running test of 10 minutes duration. The exhaust has been clear during the 10 minutes run and upon acceleration. The starting up of the engine from cold has been particularly good. We have not dismantled any parts of the engine at this period. The trouble experienced with the engine has been the failure of the exhaust manifold. EXHAUST MANIFOLD E.55578.- This manifold, during the latter part of the run at 4.450 miles, cracked approx. the full circumference of the pipe between the centre and rear joints. The cause of this appears to be due to the manifold contracting in its full length, bringing the flange holes hard on the inner side of the cylinder studs. We found that to make the manifold free, we had to elongate the holes inwards approx. .125". We had the manifold successfully welded, and during the remainder of the run, it has not shown any signs of failure. Trouble has been experienced with the G & A Joints. These joints, with the expansion and contraction of the manifold, fidget and break the asbestos, which then causes an exhaust blow to start. Once the exhaust blow has started, they quickly deteriorate, and new washers have had to be fitted. The exhaust down pipe joint at manifold has given trouble, the flange on the down pipe being too weak, the face becomes distorted and allows an exhaust blow. The expansion and contraction of the downtake pipe places a great strain upon the joint of the manifold, also at the joint to the silencer. Both these joints have failed during the 5.000 miles, and have had to be resealed. VALVES & FITTINGS TO L.O.P. E.54408. New Exhaust Valves in Firths Crown Steel E.55556/7/8 Top washers, wedges and L.O.P. Retaining parts to complete are 3X ating.- We find that it is necessary, for continual high speed work, to set the valve clearances to .006". With this setting remains, and no trouble has been experienced through the valves being open when the engine is dead cold. The valve springs have been free from noise, and there has been no undue tappet noises during the mileage. REAR ENGINE SUSPENSION Modified to Drwg. 4813 by fitting distance piece Ex. 4810 and Casing Ex. 4809. Diabolo Rubbers chamfered at each end to clear Distance piece.- The rear engine mounting does not show any blackness having developed. The n/s rubber shows more compression to have taken place than the o/s rubber. The aforesaid rubber has started to bulge between the two top plates. | ||