I purchased my latest project engine after a telephone call from a contact I had bought an engine from in the past. This farmer occasionally imports tractors from the USA, and if there is room in the container a stationary engine might also find its way over here. In this case, something had broken free in the container, causing this engine to be badly damaged: The mixer, oiler, igniter and other parts were broken. He knew that I like a challenge and he offered this engine at a knockdown price, which was reduced a little more after some haggling!
This 1-1/2 HP engine is a Fuller & Johnson Model N, serial no. 55236 and, according to the Fuller & Johnson factory records held by Stan Johnson, was shipped from the factory in January 1917 to J.H Ashdown Hardware Co., Winnipeg, Manitoba, Canada.
Before I say anything more, there are a few people that I must thank for their assistance on this project engine. Nick Lozzi must have spent hours photographing and measuring various parts for me, and Scott Barnes measured his old engine skids and battery box for me as well as providing other help. Nick is very knowledgeable about Fuller & Johnson engines, and we exchanged countless emails.
When I started work on the Fuller & Johnson, my first step was to clean off some of the accumulated grease and dirt. There was some original paint left underneath, so I did not completely strip, prime and repaint this engine. This would present other issues, namely having to age new parts and other necessary repairs to look authentic.
I stripped down the engine, removing the flywheel, cylinder head, pushrod and igniter, and then cleaned everything with kerosene.
Initially, I cleaned the engine using kerosene. Once most of the dirt was washed off, I used a paint brush and a fine plastic pot scourer to remove any further dirt and loose rust. Once “clean,” I covered the casting in automatic transmission fluid, giving it several coats to soak into the cast iron. This left a slightly greasy surface, but it brought up the color of the remaining paint. The automatic transmission fluid is easy to wash off later if necessary, unlike linseed oil or lacquer that some restorers apply to their project engines.
As mentioned earlier, the only problem in having a rusty engine is when repairs or replacements are made; the new metal of a repair is obvious and looks out of place. This can be overcome using reverse electrolysis. (See Reverse Electrolysis Primer.)
I clearly needed new timber for the skid and, again, it would be “aged.”
Pushrod and bracket
The pushrod got bent in transit and its support was broken. It was easy to return the pushrod to its correct state by applying some heat and then straightening it using a vise.
To repair the support bracket, I attempted to braze the recent break, as it was a clean break and the cast iron was not filled with oil or dirt. I cleaned off the light surface rust with a brass wire brush and applied flux, and then heated it to draw out any dirt and grease. I repeated this a couple of times, and then attempted to tin the parts. No matter what flux or tinning compound I tried it refused to take, so I had to find an alternative method of repair.
Looking more closely at the broken piece, there was another crack forming so a more comprehensive repair was needed. I turned a length of cast iron to match the external profile of the support ring and used the lathe to drill it out to 0.50-inch to fit the pushrod.
I mounted the bracket on the milling table, aligning it to the remains of the old hole for the pushrod. I milled away the end of the bracket and shaped it so when the new piece was welded to it, the hole for the pushrod would match the position of the original.
I had been given some nickel rods for my arc welder, so in view of the earlier problem trying to braze the cast iron, I used these. When I clamped the parts in place, I applied tack welds to both sides, allowing one to cool before starting the next. Then I placed the bracket in a hot oven and allowed it to heat up for a couple of hours. I applied the filling weld and immediately put the bracket in the hot oven; I reduced the temperature over the next three hours to cool it gradually.
When cool, I ground the weld and then filed it down to match the original profile. This left bright patches, making the repair obvious. It was easy to rust the cast iron where it had been touched by the file, but nickel is resistant to rust. After a little experimentation, I found that a gun barrel browning solution took the edge off its brightness.
Connecting rod and bearings
The big end bearings were badly worn in the shoulders. There were parts broken off, and the little end bearing was a sloppy fit. It was an easy matter to drift out the old bronze little end bearing and machine a new one from leaded bronze, externally 1.50 inches long by 1-inch diameter. I bored the hole for the wrist pin to 0.750-inch; I would drill the oil hole when the bearing was finally in position.
Before starting to recast the big end bearing, I checked the alignment of the connecting rod because of the lopsided wear to its bearings. It soon became apparent that the connecting rod was twisted in both the horizontal and vertical planes. This would explain why the main bearing was worn at the shoulders as, when running true at the piston end, the connecting rod would not fit in the gap in the crankshaft webs.
Rather than try and straighten the connecting rod, which is generally possible without damaging it, I took the less risky option to cast the new main bearing parallel with the bronze little end bearing. I didn’t contemplate an adjustment at the little end as there was not a lot of metal around the bearing shell.
The first step, before starting on the casting, was to shave up to 0.10-inch off the sides of the big end bearing shell to square it partially to the little end bearing and allow a better thickness of bearing metal between the crankshaft webs.
Before casting the new big end bearing, I drilled out the brass feed tube for the grease from the cup. The end of the tube was badly battered and an irregular shape, so I decided to replace it after casting the bearing.
I made two temporary spacers from 0.125-inch square steel as shims to seal the gap between the two halves of the big end bearing.
To cast the white metal bearing, I fit a recessed end cap underneath the bearing shell and machined a tapered core some 0.10-inch undersize. I cut a short metal ring to fit around the top of the shell then sealed any gaps with casting paste. At the same time, I also sealed the hole for the grease tube with paste and lightly oiled the core piece and placed it in position. I checked everything to ensure the core was central. Once the white metal was at casting temperature (when a pine stick dipped in it smoulders) I poured the metal into the “mold,” which I had preheated with a blowtorch until it was hot enough to melt soft solder.
I allowed the metal to cool naturally and then removed the casting paste and outside formers, and punched out the core plug. It then took some time to set the connecting rod on the table of the milling machine so that the length of drill rod in the little end bearing was parallel to the boring head. This involved using a number of clamps and various pieces of shim stock.
Once I had machined the bearing to size, I milled the outside faces of the bearing to be a tight fit on the journal between the crankshaft webs, carefully removing metal so that the bearing metal was a similar thickness on each side. Then I used a hacksaw to cut through and separate the two halves of the bearing. I had already marked the top faces of each bearing with a center punch to assist in reassembly. I cleaned the surplus babbitt around the bolts and their holes, ready to fit the shims. First, I used scrapers along with engineer’s blue painted on the crankshaft journal to test and fit the bearings. Once the bearings were scraped to show a good covering of blue, I drilled a 0.3125-inch hole for the brass tube to feed the grease into the bearing, and then cut the grease groove in the new metal.
Finally, I cut and fit various shims of different thicknesses.
The main considerations when fitting main bearings is to set them at 90 degrees to the axis of the cylinder and to ensure that the gears mesh properly.
The old bearings had plenty of metal, and when checked appeared square to the bore. However, there were some edges missing, no shims had been fitted and in some places the bearings extended above the main casting. The exhaust side bearing only showed wear on 25 percent of the bottom half with a thick layer of grease filling the rest, and the crankshaft was being kept in alignment with the cylinder by the outside edge of the pushrod side bearing and the crank gear. The inner shoulders of the bearings were some 0.10-inch shy of touching the crank shoulders. In short, I needed to “sort out” the bearings.
To check the alignment of the crankshaft, I firmly clamped the engine casting to the bench. I tied some piano wire to a metal bar at the cylinder end of the block, stringing it through the cylinder and stretching it to a clamped bar well behind the crankshaft. Then I adjusted the wire by carefully measuring so that it was in the middle at each end of the cylinder and passed over the 1.250-inch steel rod resting on the bearings in place of the crankshaft. I used a large set square against the metal bar and eyeballed to the taut wire. This enabled me to check the squareness of the bearing.
There was good contact on the pushrod side bearing with a good thickness of bearing metal. The gear wheel meshed well and the crankshaft was square to the bore, but I could adjust this bearing a little with a file and scraper to line it up properly, then I could use it to hold the crankshaft when pouring the other bearing.
I removed the old exhaust side bearing with a cold steel chisel and degreased and cleaned up the seat. I tilted the engine on wooden blocks and clamped it so that the surface of the bearing would be level; I checked this with a spirit level.
I lightly oiled the shaft of the crankshaft around the area of the new bearing and then clamped it in position using the other bearing for support, moving the crankshaft slightly to the exhaust side to partially compensate for the twisted connecting rod.
I fit a metal cap I had made for another casting job to the outside and cut a piece of steel sheet to partially close the gap between the crankshaft web and the inside of the bearing support. I sealed both ends of the bearing with fireclay paste and made a dam on the flat surfaces so the metal could be poured higher than needed. This is so that after cleaning there would be a good flat face rather than a curved one, which would occur when the metal cooled. I used fireclay as no babbitt putty was available, and fireclay is satisfactory as long as it is thoroughly dried out.
While the pot of bearing metal was heating on the stove, I used a torch to preheat the bearing casing and the crankshaft so that the metal would flow easily and cool gradually. This also helped in drying out the fireclay.
When the metal was hot enough to singe a pine stick, I stirred the metal and skimmed off the dross that floated to the top of the metal before pouring. Once the metal was poured, I allowed it to cool naturally before I removed the metal formers, the dry clay and then the crankshaft.
After pouring the bearings, the next stage was to fine-tune the fit by scraping them to match the crankshaft. The white metal contracts a little on cooling, and if a perfect fit is required then you should wrap a thin layer of oiled paper around the crankshaft before casting. In this case, I omitted the paper so that the casting would result in a tight fit and could be scraped to size.
Once I had cleaned off the overspill metal from the bearing edges with a hacksaw and scraper, I covered the journal of the crankshaft in engineer’s blue and then fitted and turned the crankshaft. This indicated the high spots where the crankshaft fitted the bearing and where metal needed to be scraped off to get a proper fit. When around 80 percent of the bearing is covered in blue, it is said to be a good fit.
For the first bearing, the bearing cap was well-metaled so that once I had scraped the bottom, the cap was similarly fitted. I then turned my attention to the igniter side bearing. I cleaned out the bearing casing and checked the meshing of the gear wheels, holding the crankshaft in the re-poured bearing.
For the second bearing cap, the shoulders of the bearing material were broken so I had to repour the metal. I used two end caps to hold a steel rod the diameter of the crank journal central. I lightly oiled the rod, plugged the grease hole, sealed the end caps with fire cement and created a dam down the sides. After pouring and stripping off the formers, I scraped the bearing to fit. To finish the bearing cap, I drilled a passageway for the grease and scraped out the slots to allow grease to flow across the bearing.
Once the bearings were fitted, I needed shims. I hadn’t fitted any shims before, so this meant spending a fair amount of time making a complete set, including creating pairs of equal thickness from metal shim stock to sit on either side of the bearing. I made the thickest ones first so I could use them as a template to make the thinner ones.
To allow for the bend in the connecting rod and to keep the wrist pin and crankshaft parallel, I fitted the little end bearing off-center, with 0.125-inch more metal on the exhaust side. Once the position was established I drilled the oil passage hole.
To measure the bore of the engine I first cleaned it out, but this revealed another problem: two parallel grooves in the cylinder wall, indicating that at some time the wrist pin had become loose and damaged the cylinder.
Measuring 2 inches down the cylinder showed a bore of 5.180-inch measuring the cylinder straight up and down (6 and 12 o’clock) and 5.220 measuring it side-to-side (9 and 3 o’clock).
Four inches down, both sets of measurement were 5.150 inches. The marks in the side of the cylinder stopped just short of the combustion area. There was no point in trying to hone the cylinder with the portable drill as, with the uneven wear, this might well exaggerate the unevenness. Boring is the only way to correct uneven wear in a cylinder.
Ideally, you could remove the scoring in the cylinder wall by boring out the cylinder then inserting a cast iron sleeve. Looking for a lower-cost alternative, I decided to attempt to fill the gouges with some JB Weld.
The essential part with any repair like this is to ensure that the area the epoxy has to stick to is extremely clean. To start this process, I first scrubbed out the cylinder a number of times with a brass brush and some kerosene. Once the oil and grease had been removed, I applied some caustic oven cleaner and scrubbed it into the grooves. I repeated this several times, cleaning out with water and a clean rag after each application. Finally, I heated the marked part of the cylinder with a hair dryer and cleaned any residue that oozed out with acetone and a clean rag.
Once satisfied that the scoring was as clean as possible, I mixed up some JB Weld. I applied this to the grooves, placing the engine casting on its side to stop the epoxy from running away. After a couple of hours, when the JB Weld was starting to harden, I cleaned away the surplus using a plastic disc that was sized a few thousandths of an inch under the bore diameter. Then I left the epoxy overnight to harden.
When the JB Weld set completely, I removed the remaining thin coating of surplus epoxy, initially using sand paper purely on the high spots, then carefully using a bore hone.
Read Part Two of Peter Rooke's tale of gas engine restoration in Fuller and Johnson Rejuvenation.