John Smyth 4-1/2 hp Restoration – Part 2 of 5

Peter Rooke makes a replica muffler and cart for his 1914 John Smyth engine.

1914 John Smyth

1914 John Smyth

Photo by Peter Rooke

Content Tools

Muffler

There appear to be many different muffler styles for this engine; a plain ball muffler, a ball muffler with a ridge around the gap and a “tin hat” style. Most photographs examined showed a ball muffler for this size of engine and a comment noted during the research said that the plain muffler was used on the early engines to around 1915.

The diameter for a 4-1/2 hp engine was 7 inches, but mufflers this size are nonexistent in the U.K. Indeed, there was already a 5-inch ball muffler sitting in our son’s garage in Houston, Texas, waiting for someone with spare weight allowance to bring over to the U.K.!

Thoughts then turned to making a replica muffler, the difficulty being to make the walls thick enough so it would sound like an original. With no press equipment there was no way to form a steel muffler with a 0.25-inch wall thickness, so rather than make patterns for casting I decided to fabricate one.

The first step was to make a wooden pattern for one-half of the muffler, so several bits of hardwood were glued together, ready to be turned and shaped on the lathe. This would be 6.5 inches maximum diameter to fit inside the 0.25-inch thick walls.

The radius tool for the lathe could not be set for a 6.5-inch diameter. A series of calculations were made to generate the diameter of the dome at 0.125-inch intervals so the adjustment dials could be used on the lathe to create a rough dome. This was then sanded to give a fairly smooth finish. A pattern was cut from cards to get the shape for 10 pieces to create the dome before cutting these out of strips of 0.125-inch thick steel.

These segments were then bent to shape to fit the dome, first bent on the long axis around a small pulley, and then the short axis first using the vise and then finishing off with an engineer’s ball peen hammer. Once all 10 segments were shaped, the wooden pattern was soaked in water before resting the strips on it and tack welding them all in position. 

The tack weld was then ground smooth before cutting, shaping and welding another 10 pieces on top of the first set for the desired 0.25-inch thickness. These were staggered so the new pieces covered the seams in the first layer and once more tack welded in position. Once all the segments were in place the gaps were fully welded and then ground smooth with a grinder. The other half of the muffler needed a 1.25-inch pipe nipple. The patterns were adjusted for this and another set of pieces cut. A pipe fitting was cut apart to make the threaded boss for the 1.25-inch pipe nipple. All that remained was to make six lugs, three for each side, to bolt the two halves together and weld the boss to the muffler.

Wheels

To make the 18-inch diameter wheels I acquired some 0.25-inch steel strip, 3 inches wide, along with some 0.5-inch round rod. Starting with axle hubs, I drilled a 1-inch hole through 4-inch lengths of 2-inch diameter steel. To give shape to the hubs, I cut 2-inch diameter steam pipe into 2-inch lengths, cleaned up so the 4-inch pieces would slide inside.

Before joining the two pieces, I drilled six equally spaced 0.5-inch holes through the steam pipe to support the spokes of the wheel. The steam pipe was then centered on the hub and a bead of weld was applied at each end. The hubs were then turned on the lathe to clean up the weld for a relatively smooth chamfer.

The spokes were made from 8-inch lengths of 0.5-inch diameter steel rod. To help give the appearance of an original-style wheel with reinforced spoke ends, I cut 1-inch (for the hub end) and 0.5-inch (for the rim end) lengths of 0.5-inch nominal steel pipe to slip over the ends of the spokes and then welded these to the ends of the spokes. To ensure enough of the spoke protruded to fit in the holes in both the hub and rim, I made a small jig. I drilled a 1-inch hole in a piece of 0.25-inch thick steel for the pipe to fit in before drilling a 0.5-inch hole in some 0.1875-inch thick steel for the spoke. These two pieces were aligned and welded to a piece of scrap steel to provide a base. After applying a bead of weld to hold the end pieces on the spokes, they were cleaned up on the lathe. Small holes were drilled at the rim end of the spokes so weld would flow into the middle of the spoke.

Forming the rim of the wheel would not be easy, as the 0.25-inch thick steel was too big for the small bending rolls. Before starting to bend the strip for the rim, I scribed lines marking the length of the rim, 56.6 inches. There was about 3 inches of spare material at each end to give purchase and make bending easier. At the same time, the position of the six holes for the spokes were marked 9.43 inches apart, starting 4.7 inches from one of the lines marking the end of the rim. This was to ensure that the welded join in the rim would be in the middle of two spokes to give room to adjust the arc where they meet. The six holes were then drilled using a small 0.125-inch drill so as not to weaken the rim with the result it would not bend evenly. These holes would be opened up to 0.5-inch once the rims were formed.

To shape the rim, two pieces of 1-inch diameter steel were welded to a short length of bar so they would fit at each end of the jaw on my vice. A scrap piece of cast iron with a radius of 12 inches was then centered on the opposing jaw opposite the two lengths of steel so that when the vise jaws were tightened wheel rim would bend. To check progress in bending the steel rim, a disc of wood 17.5 inches in diameter was cut to fit inside the rim.

The strip of steel being bent was 3 inches longer than needed, but was left oversize until the very end of the bending process to provide leverage for bending the very end of the rim. To start bending, one end of the steel was bent using the vise setup, the tighter curve of the former giving some compensation for spring back. One-third of the diameter was bent first before starting at the other end. The middle section was left until last in view of the length of the strip.

The template was used to check the curve, and peaks or valleys identified. These were marked with chalk and the vise was then used to get the correct degree of curve. One end was trimmed to the earlier cut line, but the other was left until after fitting the spokes. Once the rim was fully bent, the six pilot holes in the rim for the spokes were opened up to 0.5-inch. Six spokes were lightly tack welded to the hub to hold them in position so they could be adjusted to fit the rim. The hub was then positioned inside the rim. With the ends of the rim not welded together, the rim could be opened up as needed so the ends of the spokes could fit in the drilled holes. Starting on the opposite side to the join in the rim and working around evenly, the spokes were held tight against the rim with clamps before adding a spot of weld to secure them.

The profile of the rim near the join was then checked and it was clamped before being tacked in position. The alignment of the spokes was checked before cutting off the surplus steel for the rim and chamfering it to fill with weld. Clamping the ends, the outside of the rim join was welded before checking the curve against the template and bending as necessary. Finally, the inside of the join was welded and the rim joint was ground smooth. The final weld was applied around the spokes and the hub, with a die grinder and a carbide burr used to tidy up the weld.

Cart

Jimmy Priestly (majesticengine.com) advised me that the wooden rails for the cart should be 2.375-inch by 5.375-inch and 57 inches long. I located a piece of 11-inch wide by 4-inch thick timber, sawed it in half and then planed it to size. Some photographs show a battery box on top of the rails, but the 57-inch length of the engine and fuel tank gave insufficient room for this. Jimmy advised me that the battery box was probably mounted between the wood rails under the engine cylinder, which is what I opted for.

The layout of these carts puts the fixed axle at the front of the engine and the pivot at the rear. Knowing the dimensions of the axles and wheels, I scaled some photographs of a Waterloo-style cart to produce some drawings similar to the cart fittings shown in a spares booklet. Starting with the fixed axle I cut, shaped and welded steel plate to make the “H” section before adding some 1-inch diameter bar to each end, with sections of pipe added to get the required profile. The top pieces of bar had to be bent to the shape of the center piece, so these were cut halfway through to make bending easier. The slit was welded up later, smoothed and shaped with a grinding wheel. A support was needed secure the axle to the wood rails, done using 0.25-inch steel plate, with various shapes added to form the support, which was then welded to the static axle.

The pivoting axle was made in a similar way to the fixed axle, but first drilling a piece of 1.25-inch diameter steel with a 0.75-inch hole. This was welded in the center of the bottom plate before adding plates on either side of it, followed by the central bearing plate made from 4.5-inch diameter steel. Pieces of flat steel were fitted and welded either side of the bearing plate, as were the round axles at each end.

The support for the pivoting axle was made using a similar piece of steel to the static support. Two round tubes were first added to take the mounting bolts before welding on a piece of square steel that had been drilled with a 0.75-inch diameter hole for the pivot pin. These were held securely with nuts and bolts to ensure they remained in place when welded. Bar strengtheners were then added along with a 4.5-inch diameter bearing plate. All that remained to complete the pivot was to weld two blocks to the top of the turning axle for the ends of the handle. These were held in place using clamps and square blocks of steel during welding.

To fit the iron work to the wooden spars, 5.375-inch long holes 0.375-inch in diameter had to be drilled. The spars were too big to mount on the drill press to get the holes square, so a 0.375-inch diameter hole was drilled through a 5-inch length of steel that was then welded square to a piece of plate steel. This plate was then clamped to the wood at the desired location to guide an extra long drill bit to the electric drill. The handle was fashioned from two pieces of wood and some 0.25-inch by 1.25-inch steel that was drilled for the various bolts and bent to shape.

Cylinder head

The cylinder head was gently cleaned with a scraper and a wire brush to remove the old gasket before cleaning out the water passages. The frost crack in the casting was then vee’d out with a small grinding burr. This was not at a pressure point, just a crack in the water jacket, and the repair would be made by brazing. Given the size of the head this needed more than a plain propane torch, so I turned to a friend with an oxy-propane torch and a bigger brazing hearth.

He made a good job of the repair, slowly heating up the head and then allowing it to cool gradually. However, when cleaning it again a hairline crack was noticed, spreading from the repair and then crossing by the valve guides. This appeared to follow the line of the internal wall of the head and perhaps the cooling was not as controlled as assumed, with the thinner section cooling far quicker than the central part.

Rather than braze the cracks, it was decided to use plain lead solder with its lower melting point. The new crack was vee’d out, and this time holes were drilled at the ends of the cracks. These were then tapped with threads to fit brass screws. The screws were then covered in flux before being fitted.

Soldering cast iron can be difficult and to help, the cracks were first cleaned out with a brass brush, rubbed with a piece of copper tube before tinning, some pure tin paste used as the flux. It took two attempts to get a perfect watertight seal, tested by resting the head on some blocks to keep the valve guides clear of the bench and pouring hot water into the water ways.

Once the head was watertight attention turned to the valves. First, the valve guides were cleaned out using a 0.375-inch reamer. The stems on the valves were well under size and some new drill rod appeared to be a good fit in the guides so nothing more was done to them.

The heads of the valves were nearly as bad as the stems, so new valves were made. Two pieces of steel from the scrap bin were center drilled before threading 0.375 UNC. The ends of the steel rods for the stems were similarly threaded before coating in flux, assembling and then brazing. When cool the valve heads were trimmed to size before setting over the top slide to accurately measure 45 degrees using a dial indicator. The tapered sides were then cut and the stems trimmed to length before cross-drilling 0.125-inch for the spring retaining pins. It took a little time to grind in the valves as there was some deep pitting to the exhaust valve seat in the cylinder head.

Finally, a new gasket was cut, first using the head as a guide to punch the four bolt holes, cutting out the center by fitting the gasket on the cylinder head and using a sharp blade to cut around the cylinder. The waterway passages were cut out next after fitting the gasket to the head. A sharp knife and rotary burr were used to cut the various holes.

The post for the valve rocker needed replacing and stubbornly refused to move from its mounting. After heating with a gas torch it surrendered and a new one was made.


Contact Peter Rooke at Hardigate House, Hardigate Rd., Cropwell Butler, Nottingham, NG12 3AH, England • peter@enginepeter.co.uk •  www.enginepeter.co.uk