Manitoba engine restoration easier said than done thanks to US Standard/Metric bolt size confusion
At a recent car club get-together, an acquaintance had an antique gas engine in his garage. It was small (1-1/2 HP), open crankcase, liquid-cooled and had a small locking lever part bolted onto the rear left corner of the water jacket. It looked like a miniature locking mechanism for a plow, only the lever and mechanism were gone. There were a lot of people at this event and we only spoke briefly about this engine, mostly that he had owned it for more than 30 years and could not find the parts to restore it, including the ignition system. There was no trace of ignition at all. The information he had showed a Webster magneto and igniter.
A couple of years went by and he joined our local street car museum (the Minnesota Street Car Museum), which is dedicated to restoration and operation of vintage electric street railcars, and this put us in contact more often. I asked about the engine and I told him I had the knowledge and ability to get it running for him. After another year went by I asked if he wanted to sell me the engine, but he wanted to get it going. Another year went by and he called to ask me if I could make it run again.
He delivered it the next day. In looking it over a lot of work had been done, including being thoroughly cleaned, painted and new valves installed. The bolts that held the cylinder onto the base frame were new. All the babbitt bearings were good and no welding was visible, which was a real plus. On the minus side, the governor slide yoke on the crankshaft was seized up and there was no ignition. I decided to make an igniter cover plate and use a Model T coil and spark plug. The engine owner has Model T Fords and understands the Model T ignition and furnished a T coil and wire for the project.
The engine was mounted on a nice oak skid and looked good. I started by freeing up the governor slide and making the cover plate. I used a modern 14mm spark plug as the 1/2-inch pipe ones are getting expensive and I can make it bigger later to fit a 1/2-inch plug if needed.
The engine is Canadian, made in Brandon, Manitoba, and is called the Manitoba engine. As I noted earlier, the governor mechanism was missing its handle and linkage. The flywheel governor weights were in the water jacket. All I had to do was make new pivot pins and drill them for cotter pins. I made up a linkage and handle that I thought would work and it did, but it looked out of place. I had no idea what it was supposed to look like, but this was too close to the flywheel to be safe. A redesign of the handle got it somewhat away from the flywheel and a little bit safer. Finally, on try number four I was happy with the handle. Quite a lot of work and trial and error went into this, and a whole lot of thought.
The Manitoba engine had good compression, but the valve timing was two teeth off. This was easy to correct. The fuel tank and mixer are fastened together with a solid 3/4-inch pipe directly under the head, going between the skids and the tank, rearward 14 inches. A 90-degree elbow from the head (much like a Maytag engine exhaust pipe) connects the mixer and pickup pipe to the head. This will make more sense later as I get to the exciting part of this story! For a timer I drilled and tapped a #10 bolt into the timing gear. I made an adjustable sliding arm to touch the bolt and then insulated it with a hard plastic mount under and rearward of the cam gear.
With this done I was ready for a start-up. The fuel tank that was made 25 to 30 years ago was good and only needed the dust and dirt cleaned out. I was keeping the owner informed as to the progress, and he dropped off an oiler and some authentic-looking wire. Now I was ready to start it up. I use a 12-volt auto battery to run my engines; a Model T Ford runs on 6 to 18 volts, just the right voltage. The initial start-up went well, but I had to work on the speed as it was way too slow. Just as I got the engine up to 500 RPM and it was hitting and missing as it should, I adjusted the oiler and went to call the owner to have him listen over the phone (he lives 25 miles away), when there was a very loud crash, bang, clunk!
The new bolts the owner had someone re-thread and install in the main frame to hold the cylinder on had pulled out of the frame, causing the cylinder to tip forward and the piston to come out too far; the connecting rod broke the piston skirt. The pipe going into the fuel tank tore up the tank and severely dented the bottom of the tank. The only thing keeping the thing together was that it did not tear through the end of the fuel tank. The two bolts on the fuel mixer elbow pulled out of the head casting. Final analysis was that the bolts used were too small and pulled out. This engine does not use U.S. standard bolt sizes; therefore the normal US size bore of 3.5 is 0.020 under size.
I called the owner and told him what happened, and that the noise was loud enough to have my wife come out to investigate. He reaffirmed that he had paid someone years ago to remount the cylinder to the frame. In the end he was not mad and gave me the engine. I let it sit for about a year and finally took the piston and broken pieces and made a jig to hold them. I preheated the piston and nickel steel-welded it together, then used an angle grinder to get it approximately round before finishing it off in the lathe with a tool-post grinder.
Originally I had not done anything with the piston or rings, so now with it all apart I re-cut the ring grooves square in the lathe and put a spacer in to tighten them up. The bearing end of the rod was too big to go in the cylinder bore, so the piston had to go in from the crank end (someday I’m going to make a ring compressor for this). With the piston back in I went to work on the stripped-out frame bolts. The bolts must have been 7/16-inch U.S. I re-cut the frame threads to 1/2-inch by 13 TPI and put in studs with nuts and lock washers SO THIS MESS WON’T HAPPEN AGAIN! The two broken bolts were drilled out of the head and found to be non-U.S. standard threads, so I re-did all the threads to U.S. standard. I did not need another failure elsewhere on the engine.
I was able to straighten out the fuel tank and solder in a patch for the pickup pipe. I also added a drain in the bottom where the big dent was. The restart was uneventful as the engine had run well before the break-up. Re-cutting the ring grooves and adding spacers was worth the effort as it has really good compression. I made a four-wheel wagon for it so I can move it around easier. The engine runs really smoothly and nice at 360 RPM. All in all, it was worth all the work.
Contact Dave Irey at 6348 Mildred Ave., Edina, MN 55439 • (952) 943-8357