Category Archives: Technical Features
Horizontally-opposed dual four-cylinder engines with common rotary valves, certainly is a mouthful. But that is exactly what Finley Robinson Porter had finished designing only a little over a year after he left Mercer, as the Chief Engineer where he designed the legendary T-head Raceabout. This pair of engines was intended for aircraft use, and each was to be equipped with a propellor. At this point, it is unknown if this project ever went past the drawing stage, but it certainly is interesting to study his work.
We were fortunate to be able to talk with Porter’s Great Granddaughter recently and learned of this concept and its drawings. After studying them we are amazed by the vision that this man had and his ability to be able to see this concept through to its final design and drawings. It came right on the heels of the exceptional F.R.P. car he designed and built with a s.o.h.c. 454-c.i.d. four-cylinder engine that was right on the cutting edge at the time.
Just above at the top is a cross-sectioned end view of a pair of cylinders, and it shows one of the rotary valves located top and bottom on ball bearings. The intake charge enters the valve at (2) on the middle bottom and exhausts out of the top of it. The valve supply chamber (4) communicates with the feed (1) from the intake manifold and has opposed cylinder supply ports (6 and 7 – see photo at the top of the post) opening through the face of the valve.
The exhaust chamber (5) communicates with the upwardly extended tubular portion (2) that also has opposed exhaust ports (8 and 9 – see photo at the top of the post) opening through the face of the valve. The rotary valve is tapered and is smaller at the bottom than at the top. The fuel supply for the cylinders is drawn in through the bottom of the valve, and the exhaust gases are discharged through the top of the valve.
The two detail photos above show more of the construction. The left-hand drawing shows the intermediate gear (48) that is driven by a gear on the two joined-driveshafts (38). It in turn drives shaft (46) that operates the four rotary valves and gear and shaft (55) that drives the magneto on the left (52) and the water pump on the right (53). The right-hand drawing shows the details of the gears (49 and 50) that turn the rotary valve and also shows the combustion chamber. The updraft intake manifold (70) can be seen in the bottom center photo.
One of the most enjoyable parts of researching for The Old Motor articles is uncovering important forgotten automotive designs from the past. The other day we stumbled on to a large number of patents assigned to the Packard Motor Car Co. Many of them originated from within, but many were apparently designs Packard bought from the inventor and had them patent the design in the name of the Motor Car Co.
The drawing above shows a 1919 s.o.h.c. design by H.D. Church, who was Packard’s Chief Truck Designer. The Company had been involved with other o.h.c. designs at the time including the Packard Liberty engine, the 299 Packard engine and the 905 Packard. Church’s 1919 Packard overhead cam design may have been the first design for the automaker to use what Church called, a valve operating sleeve. This inverted cup (part no. 2), did away with all side thrust from the cam on the valve assembly.
You can learn more about this era including Ralph De Palma’s involvement with Packard and the racing car between 1914 and 1923 in an article by Gary Doyle at Packards International. The racing car engines were tied together with the aircraft designs because Packard engineer Jesse G. Vincent knew that it was easier to develop them in a racing car on land rather than it was in the air.
Three more designs that caught our eye can be seen left to right above: Another 1918 s.o.h.c. design also by H.D. Church; a 1918 design by F.H. Dewey for converting a Packard Truck into a railcar, and a 1911 design by M. Tibbetts for a double overhead rotary valve design.
Having been involved with Duesenberg walking-beam racing engines, finding the first application of this design to an internal combustion engine has always been of interest. The earliest reference to this concept we have found so far are these 1903 patent drawings above and below for one of the designs by none other than J.W. Packard.
The design is seen below for a two-up, two-down engine with bolt-on crankshaft counterweights. The unusual linkage designs seen above were intended for governing engine speed. You can learn more about this walking-beam engine here, and many more Packard patents here.