After scouting around for a new project, word came of an "Osborne" engine ripe for restoration. It was only being sold because the owner was trying to raise money to purchase a rare tractor. At that time, I had little knowledge of the engine's history and thought I was being offered an ordinary International Harvester. However, research on the Internet soon provided a lot of background information.
Osborne engines were manufactured by IHC while the company was under investigation by the government for unfair trading. To get around this dispute they marketed Nonpareil engines under the names of Osborne and McCormick based on the Famous, and Titan engines under the Deering banner. My Nonpareil engine, no. KG 671, was manufactured in 1911, sold by Osborne and painted blue rather than red.
There were a few small changes in the engine construction from the Famous: It was lighter, the base casting had a rounded profile, the hand plate (inspection cover) was round and the pipe-work layout was different. In the case of my 2 HP engine, some International Junior parts were used rather than those of the standard 2 HP Famous, but I do not know if this was common practice - it probably was.
The engine was basically in bits as restoration of this engine had already been started with new fuel and water pump pistons and wrist pins. In addition, new castings had already been made from a broken exhaust valve rocker and governor bracket. The cylinder head and valves were rusted and clearly required work. The cylinder bore was thick with grease and the piston appeared a reasonable fit, but I was to discover later that there was excessive wear. There were numerous pieces missing, the most important being the hand plate with the engine details on it. I later managed to read the engine number stamped on the end of the crankshaft.
2 HP Famous
Weight 840 pounds
Flywheel diameter 24 inches
Flywheel width 2-1/2 inches
Weight 615 pounds
Flywheel diameter 22 inches
Flywheel width 2-1/2 inches
As a first step, I decided to try and locate another 2 HP Nonpareil so I could copy the hand plate. If I managed to find another engine I would have a source to check dimensions of other missing parts. I placed a note in England's Stationary Engine magazine but it drew no response. I heard through the grapevine that there was an engine in Scotland. Undaunted, I decided to try and track it down. I spent a few evenings telephoning the secretaries of the engine clubs in Scotland and following up their leads. Gradually, one trail started to prove interesting and my hopes were raised when I was given the name of an enthusiast who had apparently just sold such an engine. However, I was back to square one when I spoke to him; he told me he had sold it 15 years ago and had no idea of its whereabouts!
In May we went to the annual Victorian Extravaganza in Llandudno, North Wales, and leaving my wife to go around the stalls, I set off down the engine line taking photos and stopping at every exhibit asking owners if they knew anyone with a Nonpareil. Much to my surprise I was given a name and better yet a telephone number, so I was anxious to get home and follow up this lead. Initially my hopes were dashed when I telephoned; I was told he had two Nonpariels, but not a 2 HP. However, when I told him I wanted to copy the hand plate he said he had one hanging on the wall and was happy to let me borrow it to get a casting made. Unfortunately there was no engine that I could use for reference purposes.
The original bearings were badly worn, as were most working parts of the engine. I was faced with two options - bore out the bearings and line with white metal or make new ones. Not being too skilled in pouring white metal, I decided to make new bearings and my credit card took the strain as I ordered 8 inches of cored leaded bronze. The literature I had by IHC on its gas engines refers to phosphor bronze bearings, but I consider leaded bronze to be more appropriate material for these slow revving engines.
Before starting to make the bearings, I had to remove the old ones to take measurements. After taking out the locking screws I tried to push out the old bearings with a hammer and brass drift. No joy. They were stuck fast.
Plan B was to make a plug to fit the bearing and then pull them back into the crankcase using a threaded rod. This worked.
To machine the bearings, I drove a temporary plug into the core of the leaded bronze, which I center drilled so the end of the bronze could be supported by the tailstock during turning. From the measurements of the old bearings, I turned the external dimensions and shoulders for both bearings first and then parted off the partially finished bearings.
To bore out the internal diameter, I mounted each bearing shell in the 4-jaw chuck, and concentricity set and checked them using a dial gauge. When I made the plug to remove the old bearings, I machined two shoulders on it. One matched the diameter of the crankshaft minus 0.0005-inch and one the exact diameter plus 0.0001-inch. I then used this as a gauge to ensure boring was accurate.
After completing the internal bore, I removed the sharp edges on the bearing shells with a file and used an old form tool to start rounding the shoulder that would fit against the web of the crankshaft. I checked the bearings on the crank for a good running fit.
I pressed the bearings into position and then drilled the grease and oil-way holes inside the crankcase, plus drilled the dimples for the retaining bolts with a small power drill. I took care to ensure all swarf was removed from the bearings and crankcase. I removed the bearings and set them on the lathe again to cut the grease grooves to line up with the drilled grease hole. I cut these by fitting a ground, high speed steel cutter, 0.010-inch wide, in the boring bar and cutting the groove using the hand wheel on the lathe saddle with the chuck locked in position. The final task to fit the bearings was to profile the shoulder that touches the crankshaft web. Having already removed some of the shoulder with a form tool when machining, all it needed was the application of engineer's blue to the crankshaft and a little repetitive work with the scraper to ensure a good fit. I then pressed the new bearings in place, taking care to ensure they were fit to the correct side and the grease, oil holes and locking screw dimples aligned correctly.
After I wiped it with light oil, the crankshaft was put in place and the crankshaft bearing plate was fitted with an old gasket used to check that there was sufficient side clearance and the crankshaft moved freely. It was necessary to re-scrape one of the bearing shoulders to achieve a good running fit.
I examined the big end bearing next and fit it around the big end. I guess this had been replaced during the life of the engine, as there was still plenty of metal - albeit badly scored with uneven wear. I reduced the thickness of the shims by making some thinner ones and scraped the bearing to a good, even fit in the same manner as the main bearings.
The little end had already been replaced although it was a tight fit for the new gudgeon pin. I reamed this to size using an adjustable reamer.
The photos clearly show the problems with the cylinder head - worn valve seats, corroded threads for the water pipe and plugs, and a broken rocker arm that had been repaired with plastic metal. The photo of the underside shows the rust around the valve seats; both valves needed replacement. Unlike the Famous engines, there was no inlet valve lock plate to hold the inlet valve closed.
I made new valve sleeves first by turning some cast iron to an external diameter of 0.502-inch and drilling an undersized hole for the 3/8-inch valve stems that would be reamed to size when fitted. The sleeves were made 2-1/2 inches long - slightly over length to be reduced to size later.
I mounted the cylinder head on the table of the milling machine and centered as accurately as possible over an existing valve stem hole that was drilled out using increasingly bigger drills, up to 1/2-inch. Once I had drilled both stems out, the new sleeves were coated in Loctite, pressed into position and trimmed to a flush fit. Finally, I reamed them out to a diameter of 0.377-inch to allow easy movement of the valves.
I made new valves by forming the valve heads out of 2-inch diameter steel with a 3/8-inch hole in the center for the valve stem, which I made out of 3/8-inch diameter silver steel as this had an accurate diameter and needed no machining. I brazed the stems into the new heads, which I cleaned and tapered the edge of the valve 30 degrees, ready for lapping. I was unsure about the length of the valve stem as the originals had been sawn off at some stage and the top pieces were missing. I deliberately cut them oversize to be trimmed later. I cut a 3/8-by-16 thread in the top 1-inch of the valve stem.
As can be seen from the photos, the valve seats were badly corroded. Starting with a half round file I trued up the seats, and when they were almost the right profile I applied engineer's blue to the new valve heads. I repeatedly fitted and scraped the seats until there was a solid ring of blue around the seat indicating a good fit.
Once I fit the valve, I could then gauge the length of the stems by fitting them in the head and cutting them until they were slightly longer than the horizontal level of the exhaust rocker arm. I had no idea about the style of the spring retaining nuts and whether these nuts were locked in place by a pin through a hole in the valve stem like the Famous engine or whether lock nuts were used. Despite pleas for help in engine magazines and websites, I had not received a reply from any owner of a 2 HP Nonpareil. The cylinder head has the part number of an IHC Junior (GA 7088) and a poor illustration in a parts list showed a top hat style nut. Having made the nuts to the size I thought correct, I subsequently traced another Nonpareil owner, Mike, in California who proved very helpful. Not only did he provide several photos, but also some measurements, which allowed me to make an accurate copy of the valve nuts, which were slightly larger than my originals.
The old exhaust rocker had broken at some stage and a temporary repair had been made with plastic metal, perhaps so that it could be used as a pattern to cast a replacement. I had a new one cast, which I set on the table of the milling machine and trued up the contact surfaces. I then drilled a 1/2-inch hole for the pivot pin and a 3/8-inch hole for the pushrod bolt. I drilled a 3/32-inch hole in the top of the pivot pinhole and chamfered it as an oiling point for the pivot pin.
The plugs used to block two of the waterway holes in the cylinder head were badly corroded and it was impossible to tell if they were watertight. They were probably fine, but to be on the safe side while the engine was disassembled, and also to help extract any rust in the head, I removed them. A little effort with a large pipe wrench removed one, but the other stubbornly refused to budge and I had to drill it out. I then tidied up the threads in all three water holes with a 1/2-by-14 NPT tap. Rust had eroded a lot of metal, but I planned to use gasket sealer around the threads of the new blanking nuts and pipe work to achieve a good seal. I hoped I would never need to remove them!
The cylinder came with the bore coated in a thick layer of grease. When I purchased it I tried the piston in the bottom of the bore and it appeared tight enough. However, when I removed the grease the full extent of the wear was apparent. While only a few thousandths loose at the bottom, the bore opened by 0.070-inch just below the combustion area.
Close examination of the piston also showed wear around the ring grooves, particularly the top ring, where there was a taper and the width of the groove was 0.035-inch oversize at the edge.
What should I do? I mulled over several solutions: I could get the cylinder bored out by a machine shop 0.070-inch oversize and make a new piston, sleeve the old piston or get the cylinder lined, retaining the old piston. The first solution was attractive as I could machine a new piston, but after further thought I decided to take the plunge and get the cylinder sleeved, as I found a commercial sleeve that would fit. It hurt me to pay someone else to machine the block to fit it!
Of course this was not straightforward, as the machine shop could not bore to the bottom of the cylinder without removing the cylinder head studs, which I was reluctant to do in case I broke one. However, as the wear at the bottom of the cylinder was small, it was bored to within 1-inch of the bottom. This left a small step of around 0.004-inch, which had to be lapped so the new piston rings would not snag when fitting them.
While the cylinder block was at the machine shop I decided to sort out the piston ring grooves. While I hate to remove too much metal, I opted to enlarge the 1/4-inch ring groove to 5/16-inch so standard size rings would fit. I mounted the piston in the 4-jaw chuck on the lathe and set it to run true as possible using a dial indicator. This was not easy because the piston has numerous bumps, nicks and hollows. I had to use judgment to average these out. While I could have used a parting tool to widen the ring grooves, this was likely to flex, so I made small left- and right-hand cutters out of 1/4-inch high speed steel. I also used a piece of high speed steel that measured exactly 1/4-inch to use with feeler gauges to check the width of the machined ring grooves.
Once the ring grooves were cleaned up, I tried the piston in the sleeved bore. The machine shop proudly told me the bore was now accurate. This was great, but they had not been able to trial fit the piston as I had kept it to work on. While it measured less than 4 inches in diameter in places, there were some nicks in it and it was indeed not round, but oval, so it would not fit.
Back to the lathe, and after some time setting it up again with a dial gauge, I took a couple of skim cuts so the whole piston to the skirt was 0.010-inch smaller than the bore. I then turned down the top land a further 0.0005-inch and the second land 0.0002-inch as they were likely to get hotter from combustion.
The next step was to set up the cylinder on the pedestal drill to drill the 1/4-inch hole for the drip oiler feed. I only used light pressure to avoid splintering the liner. I then cleaned the area around the hole with medium wet and dry paper.
I thoroughly cleaned the bore and checked the new piston rings for fit in the bore. To do this, I fit each ring in turn in the bore and pushed them halfway up the cylinder using the piston. I then measured the ring gap with feeler gauges. I work on 0.004-inch clearance for each inch of cylinder diameter. In this case the required gap was 0.016-inch and only one of the supplied rings needed a touch with a needle file to bring it to the correct clearance.
After checking clearances, I fit the rings to the piston by sliding them over shim stock, into their grooves.
To fit the piston in the cylinder, I used a ring compressor. I then liberally coated the piston and rings in oil and tightened the compressor.
Read part two in the next issue - making the water tank and mesh screen and repairing the magneto.
Contact Peter Rooke at: Hardigate House, Hardigate Road, Cropwell Butler, Notts, England, NG12 3AH; firstname.lastname@example.org • www.enginepeter.co.uk