A friend brought news a 1-1/2 HP Bates & Edmonds Motor Co. Bull Dog engine was for sale - at a modest price as numerous parts were missing and, while there were some castings copied from a similar engine, they all required some complex machining. The price was little more than for a set of castings for a model gas engine, so I agreed to buy it unseen.
This was a little rash as the whereabouts of the engine whose parts were used as patterns for the casting were unknown. I would need to locate a similar engine so I could take measurements in order to machine all the missing parts, but I had faith in the gas engine community from the advice received on earlier projects and that help would be forthcoming from somewhere in the world.
I was told it was a heavy engine for its size and this was an understatement - 350 pounds for a 1-1/2 HP engine; this was some over engineering! These engines were later re-rated at 2 HP by increasing the engine speed.
One sick puppy
After collecting the engine, I could not wait to get it home to examine it properly. The bore appeared excellent, and after looking at it more closely, I could see that it had been sleeved. The castings were all there although I would have to make a crankshaft, and a mixer was clearly needed as all that remained of the original was a 1-inch rusty stub sticking out of the cylinder head.
At some stage the engine had been converted from low to high tension as a hole had been drilled and tapped in the cylinder head for a spark plug. The remains of the igniter had been welded up, and there was a chain sprocket fitted on the main gear wheel, clearly used to drive a magneto.
The first task was to undertake some research and try to gather information about the engine - easier said than done. There was a section in American Gasoline Engines Since 1872 by C.H. Wendel about Bates & Edmonds, which mentioned that a great many of the engines were sold by the Fairbanks Engine Co. of New York (not to be confused with Fairbanks Morse and all the other Fairbanks companies). Bull Dog engines were made between 1902 and 1923, and in 1924 Bates & Edmonds became the Hill Diesel Engine Co.
The name tag on this engine had long since disappeared, and the area on the cylinder head where any serial number would have been stamped was covered with deep pitting from rust. No numbers were discernable, even after frequent attempts to clean the surface with emery cloth and the use of a magnifying glass. The only clue was the straight-line casting of the Bull Dog name in the side of the water hopper, rather than curved, indicating that it was a later engine.
The first step was to get on SmokStak.com and post some questions. This provided a number of helpful responses including George Andreasen, who was later to provide me with a photocopy instruction leaflet, and more important, a series of drawings and descriptions on how the rods worked and the engine was timed. The latter consisted of seven pages of text and drawings, written by Bob Kaelin, of Long Island, N.Y., to Mrs. Coon of the San Francisco Public Library in response to a request for information in Gas Engine Magazine in 1978!
All that remained of the igniter was the body minus any bracket to support a magneto, with all holes being welded shut to complete the conversion to high tension. The shape of the igniter, and the lack of any pin in the main casting for the follower rebound spring, led me to believe the engine originally had a Webster magneto fitted to the igniter, and was not a battery and coil engine as the vendor had told me. The Bull Dog is an unusual engine, working the igniter on the return stroke of the pushrod rather than the out stroke.
Finding one closer to home
I had not been wrong about the generosity of fellow engine enthusiasts, and despite receiving photographs and offers of help from the USA, I continued to hunt for a similar engine here in the UK, so I could get close and examine it. Eventually, I tracked one down in the north of England. My wife was excited when I informed her that we were going to take a rare weekend away, until she found out that I would be spending half a day looking at engines. Fortunately, the engine was completely apart from missing the trip hook mechanism. Fellow enthusiast Ian Wightman already had his engine in bits, getting ready to start a restoration, and this would make taking measurements easier.
In preparation, a couple of days were spent sketching the parts that I had to make, using a photocopy of the parts list to help identify what I needed. Once I had completed these sketches, I marked the key measurements needed and then packed my camera, vernier callipers and tape measure. I spent an interesting afternoon with Ian who was extremely helpful, in having laid out all the parts ready for me. He even said I could borrow the mixer and other items so I could take them home to copy but I was able to manage without taking him up on the generous offer. A digital camera was extremely useful as it enabled me to take countless photographs from all angles, which combined with countless measurements, gave me a great start to this restoration.
Once home, a couple of days were spent to redraw the sketches detailing all measurements, some of which were calculated from photographs. These sketches, together with photographs, were then put in several clear plastic sleeves ready for the workshop.
Tackling the crankshaft
One of the biggest tasks was to make the crankshaft, and I decided to fabricate it in much the same way as I had made cranks for model engines. This is not a high-compression engine, only of modest power, and the physical size of the crank is, like the rest of the engine, far bigger than is necessary. For these reasons I also decided to use mild steel rather than anything of better grade.
I ordered a length of precision ground 1.375-inch diameter steel, which was then cut slightly over length to 24 inches, before being faced off and center drilled on the lathe; not an easy task as my lathe is only a nominal 22 inches. Moving the tail stock to the very end of the bed, and mounting a center drill in a taper shank to fit the tailstock to save a couple of inches, I could just manage it.
The next step was to take two pieces of 2-by-1-inch mild steel, 4 inches long and bore two 1.375-inch holes, 2 inches center to center, in each to make the webs. If you have an accurate mill or digital readout the two webs can be machined separately, but if accuracy of equipment is an issue then they should be set up to be bored out together, thus ensuring both holes are exactly the same distance center to center.
The big end journal needs a rounded recess cutting near the web, so the easiest way to complete this piece was to machine it from a 4-inch length of 2-inch diameter mild steel. The main journal center section was turned to 1.375 inches, and then the recess profiled with a form tool before turning the ends to 1.375 inches to match the holes in the webs.
Once these four pieces were machined to this stage, the crank was assembled and clamped on the table of the milling machine, frequent measurements being taken to ensure the little end journal was parallel to the main bar.
The webs were to be later reduced by 0.150 inch on the outside, to leave the shoulders on the main journals next to the bearings, so this was taken into account when measuring the webs to ensure the holes would be in the middle of the remaining metal. Once satisfied, every thing was true and square.
Four holes with 0.313-inch diameters were drilled completely through the webs and the bars. After all four holes were drilled, they were reamed and then four extra long pegs cut, one end of each being slightly tapered to aid assembly. The pegs were then pressed part way into the webs locking everything in place and parallelism was again checked and found to be spot on.
The partly finished crank was then mounted on the lathe and the outer sides of each web were reduced by 0.150 inch, also cutting the rounded recess where it abuts the main shaft.
The last step before brazing the pieces together was to set up the crank on the milling table and cut the key way slots. A 0.375-inch milling cutter was used, the cut only being taken in one direction to ensure that the width of the slot remained accurate, making the slot 0.188 inch deep from the top of the bar.
Before removing the pins to disassemble the crank, every part and all pins were marked to ensure each went back in exactly the same place. The pins were then removed and a scraper used to make small slots in all the mating surfaces to be joined including the pins.
These assist by trapping flux, and improve the spread of braze as the machined parts were a very close fit and the flux might be rubbed off during assembly. Any ridges were removed with a fine file, then all parts were degreased before flux was applied and the crankshaft assembled. The pins were left to stand proud on both sides so they could be ground down later. Next, the crank was put on the brazing hearth and heat applied so that braze could be sweated into the joints and the pins.
The center piece of the main journals between the webs had been left as long as possible to keep everything true during assembly. Once the crank had cooled after brazing this redundant center section was sawn off and filed smooth. Some time was then spent with the grinder and files to finish shaping the crank webs, cutting the pins down and generally cleaning the crankshaft.
The big end and bearing caps
While there was a connecting rod with the engine, there was no big end cap. A block of cast iron was found and 0.438-inch holes drilled for the securing bolts matching the existing holes in the connecting rod. This block was then bolted to the milling table to bore out the center to mirror the connecting rod, for the big end bearing.
Once the hole for the bearing was finished, the remainder of the bearing cap was shaped using files and a grinding wheel, to match the profile of the connecting rod to mirror a photograph I had of a similar engine. To complete this task I made two new securing bolts and the nuts/lock nuts, all of which were machined from standard stock.
The castings for the main bearing caps were for grease cups rather than the oil well and flaps seen with the early engines. The first task was to clean up the bearing caps around the inside area where it touched the main casting. The holes for the grease cups were drilled and tapped, 0.375-inch National Pipe Thread (NPT), together with holes for the mounting bolts.
The threaded holes in the main casting for the cap-securing bolts had been badly rusted and I was concerned that they might need to be completely re-threaded or have inserts fitted. These threads were cleaned out with a 0.438-inch-by-14-inch tap, cutting as deep as possible into the casting and new metal, thereby slightly extending the depth of the threads. A square head bolt was turned using square stock, and rather than use dies, the threads were screw cut 0.010 inch oversize. A die was then used to reduce the diameter of the thread where it would hit the section of new thread deeper in the casting.
Frost damage discovered
It was not until the casting was wire brushed that I discovered the cracks in the water hopper, which could only arise from frost damage. One crack ran down one corner into the main body and the other was on the under side, running through the hole for the drain tap as far as the cylinder head.
The latter crack needed more than just filling as the crack needed permanent bonding near the cylinder head and around the drain hole. I am not in favor of welding old cast iron so the only alternative was to braze the crack.
As a first step, the crack was cleaned out and profiled to a "V" shape using a thin cutting disc in the Dremel, drilling a 0.188-inch hole at the end of the crack to stop it spreading. The slot was then filled with flux and heated gradually before applying braze when it reached the correct temperature. Given the size of the casting, this took two propane torches and some time! Once the braze had cooled, the surplus was filed smooth. To prevent the crack reopening when fitting the drain tap, the 0.375-inch NPT threads were re-cut to clean them out before making an adapter reducing to a smaller 0.250-inch NPT thread. This was coated in J-B Weld and screwed in, not over tight, as the J-B Weld would both lock it in position and seal it to prevent it being over tightened in the future with the risk of splitting the casting again.
The other crack was in an area of thicker casting and not subject to any stress. Again the crack was cleaned out to a "V" shape and 0.188-inch holes drilled at each point the crack changed direction. While J-B Weld could have been used I decided to experiment by using soft solder. Pieces of oversize rolled lead were hammered into the drilled holes to caulk them, a punch being used to press it below the surface. The crack was then fluxed using a powdered tin flux, which I found more effective than normal solder flux, before applying heat and the soft solder, again finishing off with a file when it had cooled. To date this has proved a successful repair method, and I think it might prove a little more durable and robust than using epoxy.
The pin support for the governor shoe was part broken although there remained just enough to give strong support to the pivot pin. This meant that any repair was more cosmetic rather than making a new pin mounting and fixing it to the casting. The end of the broken support was cleaned up by skimming 0.125 inch from the end of it and a new pivot pin turned, incorporating a 0.125-inch-thick shoulder to match the end of the casting. This shoulder provides a strong rubbing surface for the trailing arm. This new pin was then held in position by the locking bolt after it had been covered with a thin coat of oil. A cardboard collar was tied around the broken casting and then filled with J-B Weld that, after hardening, was filed to restore the pin support to its original shape.
The top of the water hopper had numerous holes in it as well as a broken section to the edge of the hopper hole. It looked as though the hopper had an extension or blanking plate fitted as some of the holes were threaded.
To repair the broken edge without welding, a short piece of steel was shaped, drilled, a thread tapped and then it was bolted in position using one of the holes in the casting. This proved support for the repair to be completed with a thin layer of J-B Weld. The other holes were filled by covering a threaded rod with J-B Weld, which was then screwed in place. When the J-B Weld had set, any surplus rod was sawn off and filed flush.
In part 2, Peter tackles the bearings and piston.
Contact Peter Rooke at Hardigate House, Hardigate Road, Cropwell Butler, Nottingham NG12 3AH, England • firstname.lastname@example.org • www.enginepeter.co.uk