Gas Engine Restoration and the Missing Piston

Don’t let missing pieces keep you from a great gas engine restoration

1-1/2 HP contract engine built by Rock Island Plow Co./Alamo Engine Co.

Dave Irey’s latest project: a 1-1/2 HP contract engine built by Rock Island Plow Co./Alamo Engine Co.

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I did some gas engine restoration work for a fellow engine collector in 2008. When I delivered the engines, he had a 1-1/2 HP contract engine built by Rock Island Plow Co./Alamo Engine Co. (as they were in business together in 1916). It has a skeleton-cast frame, 11-1/4-inch pulley cast into the power side flywheel and a 3-inch pulley on the magneto side. I’m guessing it was built on contract and sold to a jobber or special order because  the brass tag offers horsepower and serial number but no additional information.

The 11-1/4-inch pulley has two bosses cast into the inside radius of it with brass bushings and oiling spots. This, and the fact that it had a Webster magneto, were good. The bad news was that there was no piston or connecting rod, and it had a very rusty cylinder bore and a bad fuel tank. Also, the igniter was missing the anvil arm, cam and roller. All in all, though, it wasn’t that bad. A deal was struck and I went home with a new project.

Fixing the igniter 

I started by restoring the igniter. I had to make a new cam and roller assemble-advance-retard- lever with the flat spring, then make a new anvil arm for the Webster magneto igniter. This went well. I had a very good spark so all I did to the magneto was oil it; sometimes it’s best not to touch something good!

Working on the head

The round loop boss for the pushrod on the engine head was broken and had been brazed before and broken again. To fix this, I made a jig fixture that aligned the round pushrod to the head, sawed off the broken cast iron part that was brazed and electric welded with nickel rod a new round boss that was a little thicker and stronger than the original. This had to be preheated and post-cooled to keep the cast from cracking. The welding jig held the new guide in place and alignment was good.

The engine valves were good, but the springs and valve retainers needed to be replaced, so I made new retainers.

Repairing the governor

The fuel elbow mixer just needed cleaning and a new brass seat for the mixture screw, as it was all torn up from over tightening when shutting the engine off. The cam gear shaft was worn out, and the oil hole in the block with a Gitts Oil Cup on it was plugged with hard oil and dirt, so I made a new shaft and cleaned the oil passage. I took off all of the speed governor parts and cleaned and oiled them as well. I also made new pivot pins for the flywheel weights.

The latch end of the pick blade on the governor system was worn and battered, so I had to weld a little on it to make it smooth. All of the springs on the engine were shot or missing and it was a challenge to get them right again. The crankshaft, flywheels and main bearings were very good, and removing two shims on each of the bearing caps made them fit well.

An elusive piston

Meanwhile, I had been looking for a piston and rod without success. But then, at the Power Show in Hastings, Minn., I bought a 1-1/2 HP John Deere rod with no cap for $2. At the same show, a guy had a rod cap but it was 3/8-inch too wide and didn’t bolt up. I solved this by cutting it in half and welding it back together while it was bolted tightly to the John Deere rod. I will have to repour the babbitt later.

I rebored the cylinder to get rid of the rust and pits. I told a neighbor that the bore resembled a gopher hole, but he isn’t an engine person and did not see the humor in my sarcasm. When I finished the rebore, I had a bore that was 0.020-inches oversized. I’ve gone to several power shows and swap meets and have measured a lot of pistons, but haven’t found the right one yet. The best one I’ve found was just a little too big, so I turned it down 0.025-inch, but it was too thin and would have broken. I also looked in several truck and tractor books, but didn’t find what I wanted. Quite often, the wrist pin was 1- inch, and I needed one 3/4-inch to look authentic and fit the rod. I finally ordered a mostly finished cast aluminum piston and rings with a 3/4-inch wrist pin. This took some final honing to get a good fit. My $2 John Deere rod was 3/8-inch too long and had to be shortened by cutting it off and welding it back together. This was done by making a jig of 3/8-inch flat steel 14-inches long and 3-inches wide. I drilled a 3/8-inch hole in the flat steel and bolted the wrist pin to the steel plate, then made a steel dummy shaft 0.020-inch smaller than the crankshaft. Then, a wooden dummy rod pattern was sawn out on the band saw and fitted to the steel plate to get the correct length, which was 3/8-inch shorter. Another 3/8-inch hole was drilled, the pattern removed and the pin bolted down.

Next, the John Deere rod was sawn off and V-cut to create a good welding surface. I preheated and arc welded the piece back together. Some serious clamping also went into this to hold it in place and ensure that it was true. The post-cooling was done on an electric shop stove, and I did some final grinding with my small hand-held grinder. The babbitt was then repoured and I machined it on the milling machine to fit the crankshaft.

Making a new fuel tank

The fuel tank was shot and full of old solder patches so I decided to make a new one. I don’t have a metal bending brake, so a piece of angle iron had to do. I do have a couple of duckbill bending pliers and a table saw with a cast iron top that were used to make the 90-degree bends in the angle iron.

First, I made a paper pattern so I could get the correct measurements: 2 inches tall, 4-1/8 inches wide and 12 inches long. The original tank is longer, but I don’t need that much fuel capacity. There is a 12-inch, three-layer solderable seam going the length of the tank, 1/2 inch down from the top along one side. The end caps were bent with the 4-inch duckbill pliers. All sealing surfaces were tinned before soldering. I used 50/50 acid core solder and neutralized the work when done. It took a few tries to get all the drips done. New mounting hardware was made and a new fuel line and check valve were fabricated. I also put a drain cock in the bottom of the tank. With all of the parts done, it was time for final assembly.

First, a four-wheel wagon was made. I used 8-inch steel wheels and 5/8-inch solid steel axle shafts. I made the handle out of new 7/16-inch round shaft. A neighbor had some 4x6 fir wood I was able to use for bolsters and rails. The wagon has a nice old look to it.

The final assembly went fairly well. The pushrod for the magneto sat too low in the roller I made so I had to make a few rollers that were 1/8-inch thicker. This raised the arm up and now the alignment is correct and the timing can be set. All of the springs were either rusted out or missing. I have a large spring collection and still had to make a couple trips to my local hardware store. It took a lot of time to get them all made – 13 springs in all with four in the governor alone. I did not repaint this engine – just clear coat.

Time to start it up! This went fairly well as I have restored many engines, however the governor wanted to latch up at 150 RPM and I would only get one or two fire pulses before the engine died off. Another trip back to the spring box, the addition of a couple more springs and some adjusting got the engine running at 550-600 RPM. When the rings set, I will slow it down some.

This was a 2-1/2 year, spare winter time project. There were no major problems – just a lot of little ones. But this is what I enjoy doing! Recently, just by chance, the former owner stopped by and liked what I had done. The only question that I have now is, what was the original use of the engine?

Contact Dave Irey at 6348 Mildred Ave., Edina, MN • (952) 943-8357.