Editor's note: This article is the second installment of a two-part series chronicling Craig Prucha's restoration of a 25 HP 1901 Swan oil field engine. Part I appeared in the March 2004 issue of GEM.
With the engine bed and cylinder prepped, I turned my attention to the sideshaft assembly. The sideshaft was pretty well rotted away, so I made a new one from stainless steel and bought a new set of gears for driving the governor. The new gears are nice, and they came with a small hole bored in the center so I could machine the gear's bore for my particular application. I was very fortunate to find gears that exactly matched the center distance of the sideshaft and the governor shaft. There are, however, some differences between the original gear set and the new gear set. For one, the number of teeth per gear is different (although the ratio is the same), and the tooth profile of the new gear set is different.
The governor assembly was the next part of the restoration to tackle. The governor shaft was rusted solid in the governor housing, and the governor housing had a crack in it from rust and moisture swelling and expanding. The governor parts are pretty fragile, so to make sure nothing broke during disassembly I drilled out all the pins holding the governor balls. I cut off both ends of the center shaft and heated up the housing with a torch. I did this repeatedly - followed by a good soaking in kerosene - but I still couldn't get the parts to free up. Finally, I put the governor housing in a press, and the shaft started to move. The shaft finally came out, and I repaired the cast iron governor housing by welding the crack with Ni-rod and grinding it flush.
With a materials list in hand, I made another trip over to my friend Dave Johnson's shop and got the necessary stock to fabricate a new head and cylinder sleeve mounting plate. The engine was also missing the brass bearing halves for the connecting rod big end and the strap that holds the big end and bearings together on the crankshaft. Using a bearing half of similar size from another engine, I fabricated a pattern for two bronze castings, one for each bearing. I fabricated the strap for the connecting rod, and after getting the bearings back from the foundry, I machined them up.
I first squared up the bearing halves on a shaper and clamped them in a four-jaw chuck on my lathe. I put a piece of 0.060-inch nylon shim stock between the two bearing halves and machined the bore to size. I faced each side of the bearing assembly, and machined a chamfer into the inside diameter of the face to make clearance for the radius of the crankshaft. Finally, I drilled an oil hole and cut oil grooves in the bearing surface. I assembled the bearing halves together with the strap and the connecting rod.
Next, I turned to pouring the crosshead babbitt. Before I could pour the babbitt, however, I had to finish the cylinder sleeve mounting plate and mount the cylinder sleeve. And that meant I had to finished fabricating the new piston connecting rod - all or which play a critical role in aligning the crosshead.
The cylinder sleeve and piston came back from the shop, and the connecting rod turned out nice and fit the piston well. I temporarily rigged the sleeve to the bedplate, installed the piston and piston connecting rod in the sleeve, connected the rod to the crosshead and spent a lot of time lining everything up to make sure the crosshead ran true with the piston. Once this was done, it was time to pour the babbitt. The pour went great, and I poured extra babbitt on the top side of the crosshead so I could machine the final height of the crosshead bearing surface. This also insured that the top of the crosshead would be parallel with the bottom: A final inspection showed the crosshead was properly located. The Swan was starting to look like an engine again.
1 fabricated six new 38-inch-long, 1-1/4-inch-thick tie rods (the rods that bolt the head and cylinder assemblies together and also to the bedplate). I also had to finish turning the outside diameter of the new head and drill the six mounting holes for the tie rods. This wasn't without its challenges, as I discovered the six holes for mounting the head were not evenly spaced. I wound up having to transfer the position of the holes from the existing head and labeling the new head's orientation. Also, the original head had a boss or protrusion that went 3-1/2 inches into the combustion chamber. That's an awful lot of material to machine, so as an experiment I made the new head flat. I did this to increase the combustion chamber size, which also lowered the compression.
Now it was time to start assembling the cylinder. I had already bolted the sleeve on with some temporary 'T' bolts. The water jacket and the combustion chamber each have two cast ears to bolt them together and hold them in position while assembling the six tie rods. The head and cover plate were the last two pieces that had to go together, and I cut gaskets for every interface. With everything lined up - checked and double-checked - I started tightening up the tie rods. Before I put the final torque on the tie rods, I loosened the bolts holding the water jacket and combustion chamber together so they would not fight against the tie rods.
With this done, I cut gaskets and put the valve chests on. Next up was the mixer, which needed a little work before I could bolt it up. I re-cut the seat for the gas valve (it holds the gas back until it sees a vacuum from the engine) and made a new shaft for the butterfly valve. I reamed out the shaft holes in the mixer housing and installed new bronze bushings. With that work done the mixer was like new.
With the mixer installed, 1 could install the governor assembly and line things up to pour the babbitt for the governor and the sideshaft. This required a lot of measuring, as the governor, sideshaft and crankshaft have to line up and have the correct relationship with each other so nothing binds up. After checking the setup a couple times, I poured the sideshaft bearings.
The next step was attaching the connecting rod to the crankshaft, and with those parts assembled it really started looking like an engine again. For the first time since I'd bought the Swan, the piston and crosshead moved together when the flywheels were rotated. What a great feeling! I noticed in setting up the engine that it got tougher to set the bearings as I progressed - it's tough to feel the drag on things like the crankshaft and crosshead when the mass of parts starts coming together. Yet, everything seemed to be working well as the flywheels rotated: The governor balls actually went around - what a site!
I still had to fabricate the exhaust cam lobe, which was missing from the engine. I made the lobe of the exhaust cam quite wide to make sure I had enough material to achieve the right duration on the exhaust valve. I used the existing intake cam lobe as a reference, since they are effectively similar aside from the exhaust cam lobe profile being different than the intake cam lobe.
This led me to the rocker arms, which needed some attention. I had to make a new rocker arm pivot shaft and had to bore the pivot holes in the rocker arms and press in new bushings. Both rocker arms also needed new rollers and shoulder screws, which I made. I also fabricated new valve adjusters.
Fresh Air and First Fire
Suddenly, it was time to pull the Swan out of the shop and put the final touches on it. The flywheels still had to be painted, a chore my two sons Joseph and Christopher took care of once the engine was outside. I installed the gas line and gas valve, and also fabricated and mounted an air intake pipe and choke plate. I fabricated a hot tube chimney and plumbed up its gas line. I finished rebuilding the governor linkages and welded up the pivot holes, re-drilled them, reamed them to size and made new pivot pins. All this work made for a nice, responsive governor.
The day finally arrived to start the Swan. I hooked up propane tanks and an accumulator, lit the hot tube and oiled up the engine. I rotated the flywheels to make sure everything was working properly and stopped the engine on its power stroke for priming. Not sure exactly where to set the gas and air, I made an educated guess. Was the hot tube the right length? How much fuel would it need? How much air? I'm sure many of you have been in this situation.
When I felt things were ready, I primed the engine with gasoline and back-kicked it. I did this quite a few times, but I didn't even get a pop out of it. Looking around my shop, I saw my Ferguson TO30 tractor. I backed the tractor up to the engine and put a belt over the flywheel. I don't really like starting an engine this way, so I spent a lot of time making sure everything was lined up right. With the compression release open and the tractor pulling, the Swan's flywheels started to rotate. After making sure the belt was tracking okay on the flywheel and everything on the engine was working properly (sideshaft, rocker arms, valves, etc.), I closed the compression release, opened the gas valve, and the Swan fired in a few short seconds. It was firing erratically and running lean so I gave it a little more gas - but it was running. Quickly, I went over to the tractor and put the PTO in neutral. With a small pipe, I slid the belt off of the flywheel. Wow! I wondered how long it had been since the Swan had last run under its own power.
It wasn't knocking or making any load-related noises, so I started adjusting the gas and air mixture (it's a throttle-governed engine). After a few minutes of adjusting, the Swan started slowing down and hit every time - it sounded nice. After about 20 minutes of running - and my heart going a mile a minute - the engine made a loud bang, but kept running. Listening, I could hear a hissing sound every time the piston came up on compression. I discovered that a cover gasket on the exhaust valve chest had blown, so I shut the engine down. Also, I didn't have any water in the engine, and it was starting to get a little warm.
After removing the cover and gasket from the exhaust valve chest, I decided to machine the cover mounting surface and true it up. I cut a new gasket and reassembled the cover.
I plumbed cooling water to the Swan, then checked and readjusted anything that needed attention. My good friend Stiles Bradley stopped by to lend a hand, and I lit the hot tube and oiled the engine again. We primed it and back-kicked it, and with the two of us working together the engine fired. 1 had left the gas and air settings where they were from the last running, and the Swan took off right where it left off. What a day! We watched the Swan run and fiddled with adjustments here and there, but boy, it was running nice. When the engine fires I can hardly hear a bang. It's more like a whisper. I have the entire restoration on a four-hour video, and I love watching it and reliving the experience. It's a great-running engine, and it's currently on display at the Coolspring Power Museum in Coolspring, Pa.
I would like to give special thanks to Stiles Bradley and everyone else who helped me with the Swan's restoration. I couldn't have done it without them. Thanks.
Contact engine enthusiast Craig Prucha at: 6810 Ellicott St. Road, Pavilion, NY 14525; email@example.com