NC7251 in the Lake District of Northern England after a shake-down run to bed in the pistons and liners.
View of the engine from the left hand (passenger side in the UK) with the Magneto and drive shaft visible in the lower foreground, the inlet manifold running over to the carburettor on the other side of the engine, the exhaust ports (manifold removed) dynamo regulator on the firewall/bulkhead at the right hand side of the picture, the water pipes out of the blocks/heads running up to the radiator and the exposed valve springs. The tappet blocks below the valve springs are shown in a closer view later. The Brass crank on the bulkhead goes across the back of the block to operate the carburettor cold-start device. I seem to remember that the ignition coil had a ballast resistor and this is probably the object on the far side of the bulkhead above the back pair of spark plugs. This engine had dual ignition systems, and could run on either or both, like an aircraft engine.
The right-hand side (driver's side in the UK) showing the lower water manifold which would run into the water pump, except that it was not on the engine when the picture was taken, The selection of bell-cranks and levers at the base of the steering box are the mixture, spark advance/retard (working on both the magneto and coil ignition) and hand throttle. The oil filler cap is just behind the steering box, the coil ignition distributor and pressure pump for the petrol tank are on the right of the shot. The threaded inlet manifold feeder to the carb is seen peeking under the HT lead distribution tube, the cylinder oil pipe is seen running across the blocks with individual connections to each bore near to the bottom flange.
View of the top of a single cylinder block, with the bronze covers above each valve, the magneto driven spark plugs above the inlet valves, the coil-driven plugs in the centre of the bore. The top water cover was a collector for all three cylinders in each block, and was different for the rear cylinder as the radiator feed was not present..
View along the length of the engine, with the bulkhead in the background showing the piped wiring and the ignition ballast resistor on the left hand side. Brass pipe connections on the bulkhead are for the petrol pump, tank pressure gauge and oil pressure gauge.
The petrol pressure pump that keeps the tank lightly pressurised when running. The tank is pressurised by a hand priming pump on the dashboard before starting, and the pump takes over after once the engine has started. A relief valve keeps the pressure to a couple of pounds per square inch.
Exhaust and inlet port side of one of the two blocks before removal, the exposed valve gear throws a fair bit of oil around, but the engine is fairly slow-revving so the mess is not too bad. The tappet block covers hide the pivoting rockers that transmit the valve motion from the camshaft to the valve stems. Adjustment is made at the tappets, felt pads are provided to cut noise down. The bell-cranks that come through the centre of the block can just be seen on the extreme left, these are the controls for the Magneto.
A view of the top of one set of cylinder blocks, showing the dual plugs and valve covers. This is the rear block with the smaller water outlets.
Another fron view showing the fan, which is belt driven. The water pump is driven off the timing case, the dynamo is driven off the gearbox input flange.
A view of the tappet blocks with the cam followers and their housings above. The conventional valve adjustment method is also shown.