Experience with a Piston Valved Stanley Engine.

In December of 1995, I bought a cylinder block from the late Carl Amsley. This block, which is identical to that shown in SACA drawing set number 205, was not in very good condition, but looked to be useable. After having one cylinder bored forty thousandths of an inch over size, and making a steel brace to replace the broken ears for the diagonal tie rods used in condensing Stanley engine mounting, I rebuilt my engine with this block. As the block was designed for inside admission valves, the crank shaft was taken apart and reassembled with the eccentrics reversed in phase from the normal Stanley configuration. This involved cutting a new key way for the drive gear and the eccentrics. I did not get this exactly right, so valve events were slightly earlier than they should have been, making the engine slightly rough in short cutoff.

This engine was used for more than three years, or about twelve thousand miles. During this time, it was opened up for work twice, and suffered two on the road failures. The first event was the failure of some of the bridges between ports in the valve bore sleeve, allowing the valve piston rings to catch in the port with the result that the valve and the sleeve were each broken into two parts. Fortunately, this happened at a low speed while the engine was in long cutoff, so the links and the rest of the valve gear were unharmed. It's a good thing I have AAA+!

To repair this, I made new sleeves and valves, taking the opportunity to increase both the valve diameter and the port areas. The result was a noticeable increase in performance, observed in my fuel mileage and in a marked increase in range with one tank of water, to more than a hundred miles. In this configuration, the car completed the 1996 season and ran until the spring of 2000.

By the end of the 1997 season, I had observed a roughness in the torque when climbing hills at slow to moderate speeds. On opening the engine, I found significant wear of the rings in the valve pistons and fitted new rings. The wear was particularly marked at the ends of the rings, which were step cut. I suspect that this may have been the effect of the ends having to cross ports, and using slant cut rings may be an improvement. The main pistons and their rings were in excellent shape, and were re-installed.

The most of the time the engine was in use, I used a superheater providing steam at about 650 degrees Fahrenheit. However, wanting the best possible performance during my try at climbing Mt. Washington in 1999, I fitted the superheater I call "El Kabong", eighteen feet of three/fourths inch heavy wall stainless tubing, after I arrived in Gorham. This produces steam temperatures between 750 and 800 degrees in normal driving and kept the temperature above 700 during the entire climb, which required steam pressures, at the engine, above 450 psi.! I do NOT recommend such temperatures be used in a slide valve engine! However, the piston valve engine showed no signs of distress, so I left "El Kabong" in place for the rest of the season, with a slight but not significant increase in efficiency. My own feeling is that once the superheat is high enough to keep the steam dry throughout the engine cycle, a further increase in temperature produces no significant effect, except to the detriment to the lubrication oil.

In the spring of 2000, having driven the car 1500 miles in this season, the engine suffered a crank failure, followed immediately by the unrestrained piston breaking the end out of the cylinder. As this happened only a few weeks before the Vermont tour, I had to scramble to get the car running again, rebuilding the engine with a spare crankshaft and slide valved block. Thus endeth my experience with a piston valved Stanley.

In conclusion, I might comment on the results. This block is not an optimal design, the valves are rather small and the ports between the valves and the cylinders rather long and tortuous. None the less, it was a significant improvement over the standard Stanley block, adding about five miles an hour to my cruising speed. The use of piston valves greatly reduces the forces on the valve gear and the amount of oil needed for effective lubrication. For these reasons, alone, this design may be worth while for those drive their condensing cars a lot. However, one should not expect to get racing performance from this design!

David K. Nergaard, 13 September 2000

This paper was used as the basis of a talk given during the SACA Danville meet, 16-18 September, 2000. For what it is worth, the author is preparing to make some cylinder blocks similar to the one described above. Interested parties should contact him quickly.