Restoring a 1-3/4 HP Monarch – Part 2

By Staff
1 / 22
The Monarch’s broken governor weight.
2 / 22
The governor weight after brazing and addition of the strengthening rod.
3 / 22
Completed repair to the governor weight.
4 / 22
The governor weight after brazing, drilling it for the support rod.
5 / 22
Inside the magneto after removing the front plate.
6 / 22
The cracked top cover.
7 / 22
The magneto as removed from the engine.
8 / 22
Cutting the slot in the electrode.
9 / 22
The bent electrode.
10 / 22
Movable electrode after cutting the taper, ready for brazing.
11 / 22
Speed lever with new spring before assembly.
12 / 22
The assembled magneto and igniter.
13 / 22
Magneto trip finger showing the wear before it was squared off.
14 / 22
The old and new roller.
15 / 22
The first cut of the cast iron on the band saw.
16 / 22
Cast iron block with the corners sawn, marked out ready to mount in the 4-jaw chuck.
17 / 22
The muffler interior bored out prior to cutting the thread.
18 / 22
The front plate after brazing profiled section.
19 / 22
Using the mill and rotary table to mill the edges of the front plate.
20 / 22
Completed muffler front plate.
21 / 22
Ready to braze the bolt supports. Note the recesses cut for the lugs.
22 / 22
The finished muffler.

The following is Part 2 of a three-part series documenting Peter Rooke’s restoration of a 1-3/4 HP Monarch badged by Nelson Bros. Read Part 1 here.  

Governor weight
One of the governor weights had broken off in transit, splitting not far from the pivot hole. While it was possible to cast one using the unbroken governor weight as a pattern, this was not something that I could do myself. Before considering casting an attempt was made to try and repair the weight.

Both sides of the break were given a good cleaning with a brass brush and were then coated in soldering flux before heating to brazing temperature to draw out all the dirt. Despite being a recent and clean break it was amazing the amount of dirt that came out of the casting, which turned the flux black.

When the pieces had cooled, the flux and dirt were wire brushed off, also using a sharp pointed cutter in the Dremel to clean out the crevices. Again, both pieces were coated in flux and the process repeated until the flux retained a degree of its original color on heating. Then it was time to braze the two pieces together.

After cleaning and fluxing the two pieces, they were wedged in the correct position on the brazing hearth. In order to avoid overheating the thinner section and destroying the properties of the flux, heat was first applied to the section by the body of the weight then, when at brazing temperature, the flame was moved up to the other parts of the repair. Once the braze had flowed and the repair made, the weight was covered with fire bricks and allowed to cool slowly to stop the iron from becoming brittle.

To support and strengthen the repair, a hole was drilled lengthways through the area of the break so that a 0.125-inch steel rod could be inserted. The area around the rod was cleaned and the rod covered in flux before it was pushed into the hole. The weight was supported then heated once more, and braze touched to the rod so the rod was firmly soldered along its length. Again, it was allowed to cool under the warm fire bricks.

All that remained was to clean off any surplus braze and file the end of the rod smooth before priming.

The screw that was holding the hard steel latch plate in place on the detent arm was broken with only one side of the slot left, with the result that the plate was not held firmly in place. To remove the screw, a center punch was placed against the remaining side and repeatedly hit with a hammer to unscrew it. A new screw was made to complete the repair.

Igniter and magneto
The magneto, a Webster Tri-Polar model AMM, and igniter had clearly seen better days; the return springs were badly rusted, the moving electrode was bent, corrosion was coming through the paint of the terminal cover plate which was cracked and the brass band had been broken and roughly repaired. This was before even trying to test the magneto to see if it worked! An inspection of the mounting studs showed that they all appeared reasonably sound.

As a first step the rusty return springs were removed, but the rollers were stuck so release agent was used and the magnet clamps were removed in order to release the brass band. After lubricating the inductor spindle, there was resistance when turning the rotor, but it was not clear whether this was through magnetism or dirt in the bearings.

The spring arm was removed next, along with its small key which was carefully stored. The front plate screws were removed and then the front plate was very gently eased off, taking extreme care so as not to break the very thin edges of the plate. Once off, the internals could be examined and it all appeared to be in good order with no signs of corrosion. There was little movement in the inductor bearings, and looking at the inside of the plates, it appeared that the old bearing had been drilled out and new ones fitted. The bearings are an integral part of the plates and this is the only way to replace them as trying to press them out would only crack the plate. It was clear that the magneto had been refurbished at some stage of its life as there was gold spray paint over the rotor and coils, the coils perhaps themselves being replacements as the wiring appeared good.

The terminal cover plate was broken, but only in one place, and both parts were there. An attempt was made to use epoxy glue to bond it together rather than buying another one and to date this has held.

The front plate was refitted and a nut was screwed on the shaft which was then turned by using a socket in the drill chuck. To test the output of this MM model magneto, it should register 13 volts when the inductor is turned at 590 RPM. As the inductor turned fairly freely after cleaning, I suspected that the reading would not be good through lack of magnetism in the magnets – I was proved right. The meter only indicated 4 volts but fortunately I had just built a magnet charger, and after a couple of seconds on it, the voltage was checked again and found to have increased to 12 volts.

New return springs were acquired from Hit & Miss Enterprises to replace the tired old ones. The rollers appeared in perfect condition and turned freely after cleaning and oiling.
The Webster was assembled and given a coat of paint – gold for the body and black for the magnets and magnet clamps.

The igniter bracket was inspected and was in generally good order apart from a rusted return spring, broken spring on the control lever and a bent movable electrode.
Rather than make a complete new movable electrode I decided to retain the head and fit it to a new shaft which I would make out of drill rod for durability. The contacts on both the fixed and movable electrode looked new, and the mica tube and washers also appeared sound.

Before repairing the electrode arm a careful note was made of the position of the key slot in relation to the head by marking the head with a pin punch. The first step to repair the electrode was to set up the old one in the 4-jaw chuck so that the head ran true, then all but 0.700 inch of the shaft was cut off, the last 0.625 inch of the remaining spigot being turned down to 0.156 inch diameter.

A length of 0.312-inch drill rod was then set up so that 0.300 inch of it could be turned down to 0.250 inch ready for threading and 0.438 inch tapered to fit the electrode arm. This taper was cut by offsetting the top slide so the dial indicator showed a movement of 0.032 inch when the slide was adjusted by 0.438 inch. The fit of the taper was checked to the electrode arm by coating the inside with engineers blue, fitting the new shaft then checking for coverage. If full coverage is not shown then the top slide should be adjusted and the taper re-cut. When satisfied with the fit of the taper, the 0.250-inch by 20 threads per inch taper was cut, the length of the thread being trimmed to a length of 0.250 inch.

The tricky part is to cut the slot in the taper for the woodruff key. I mentioned in earlier articles that as I did not have the correct cutter, the cutting disc for a Dremel had been successfully used. This exercise was repeated, setting the shaft on the vertical slide which was fixed on the lathe cross slide. The cutting disc was held in a collet and centered over the shaft. With a very fine feed to prevent breaking it, a new disc was used to start the slot, stopping when the slot was 0.500 inch long. The disc was then swapped for an old one that was the smaller correct diameter which was then used to deepen the slot without lengthening it. Once the slot was the correct depth and profile, the shaft was moved so that a few thousands of an inch could be removed from each side to get the slot the required width of 0.062 inch. It only required a few touches with a needle file before the key fit.

Once satisfied with the fit of the new shaft in the electrode arm, it was cut to length so the whole arm matched the original. A 0.156-inch hole 0.650 inch deep was made in the end of this arm, drilling slowly and without cutting oil to keep it clean for brazing the spigot on the old head into it. Before fluxing the spigot, several deep lines were scored along it to trap flux and provide an escape route for any air trapped in it. The new arm was fitted and aligned so that the earlier punched mark on the head lined up with the key slot.

After brazing, the arm was allowed to cool before cleaning up around the joint. The taper cut in the head was then covered in grinding paste, before fitting the arm in the igniter and twisting it several times. A clean ring in the seat showed good contact all around; if this was not the case then grinding would have continued until the fit was perfect.
The trip finger on the Webster was badly worn, so the fine grinding wheel was used to true it up. There was a lot of sideways play on the trip arm, which could have hit any part of the trip finger resulting in large timing differences.

The spring for the control lever had already been purchased from Hit & Miss Enterprises and was supplied complete with two rivets. These were used to fix the spring to the arm by putting the rivets in position through the spring and arm, before hitting with a hammer while resting the spring on a metal block.

There had been some wear to the roller, as there was a flat spot indicating that it had become seized in position, and the trip finger had worn it away. Using the measurements from this roller, a replacement was made on the lathe. Once these repairs were completed the igniter was assembled with care being taken to ensure that all mica washers were unbroken and the stack was 0.125 inch thick to fully insulate the fixed electrode.

After fitting the Webster to the bracket, the electrode arm screw was adjusted so that it nearly touched the push finger. New wire had already been fitted to the Webster output terminal and this was connected to the fixed electrode so that the igniter could be tested.

Using the starting lever the Webster was cocked and released while watching the contacts and success – there was a nice fat blue spark!

There was no muffler and a quick search of the online catalogs did not reveal a source for a replacement that resembled the original. Fortunately, I knew what the original looked like, having seen one at a local engine show and being able to take a couple of photographs as well as some measurements.

The sensible course of action would have been to make patterns and get the muffler parts cast, but, as usual, I like to try and solve the problem myself, even if it means a lot of work. My time costs nothing since I’m retired!

I started to look for a chunk of cast iron I could recycle to make the muffler and a friend turned up with a lump of cast iron that used to be part of a railway points system.

To get to a core out of which I could turn the muffler body, it was necessary to set the block on the band saw and rough cut it to shape. There was enough metal to not only form the body of the muffler but also a pipe to the cylinder head, thus avoiding having to fit a nipple. Fortunately the band saw could be left to work as it took some time to cut through the cast iron and also blunted one blade. The skin of cast iron can be extremely hard and this was no exception.

Once the block was rough sawn, the corners were also sawn off to make it easier for turning on the lathe, with the front and back being faced off on the milling machine.

The block of iron was then mounted on the lathe using the 4-jaw chuck, and the exterior turned to a diameter of 5 inches before reversing the block in the chuck to turn the spigot. When turning this to size to mirror a 1-inch nominal pipe, it soon became apparent that there was a large blow hole in the middle of the block of iron. This meant a re-think was necessary, so the majority of the spigot was cut off and the remainder was bored out and threaded so that a 1-inch nipple could be used. While the thread on the inside would not be perfect with the bad casting, it could be made tight with sealing compound when the nipple was fitted.

Inside the muffler, the central core was bored to a diameter of 1.156 inch ready for threading 1-inch national pipe thread (NPT). This core was left 1.750 inch wide, hollowing out the remainder of the iron and leaving a rim 0.188 inch thick.

In view of the force needed to cut the 1-inch NPT with a tap, the thread was started by screw-cutting under size on the lathe after the hollowing out, while the muffler was still centrally mounted in the chuck. The muffler was then reversed so that the back edge could be rounded using a profile cutter and files. Afterward, it was removed from the lathe and held in a vise so that a tap could be used to finish off the thread.

To make the front plate, a scrap flywheel was used as the main part, turning it to the thickness required, leaving a cylindrical section on the inside to fit over the raised  center of the main body so the exhaust gas was deflected back before they exited from the front. The cast iron was rough turned to the inside diameter of the muffler body, 5 inches. To cover an old hole in the middle of the cast iron and also provide a raised boss, a piece of iron was turned then, with two 0.125-inch-thick strips of iron to lie under the mounting bolts, it was braised to the cap.

The next task was to drill the two 0.250-inch holes in the cap for the mounting bolts to act as reference points. To complete the profile of the cap, it was set up on the rotary table and milled to produce the diameter that would fit inside the edges of the muffler, leaving four lugs to seat in the wall of the muffler. After milling, the corners of the lugs were not square, but were easily cleaned up with a file.

All that remained to finish the cap was to mill a series of recesses in the rim to allow the exhaust gas to pass. Nine were cut in each quarter, indexing the cutter using the degrees shown on the rotary table.

To provide support for the securing bolts of the muffler, steel blocks were needed inside the hollowed muffler. First the four recesses were cut with a hacksaw and filed to align with the lugs of the cap. The cap was then fitted in position so that the 0.250-inch holes for the bolts could be drilled through the main body. The main part of the muffler was next set up on the milling table, and using one of the drilled holes as a reference point, a 0.500-inch slot drill was next used to enlarge the holes through the back of the muffler casing.

Some 0.500-inch-diameter rod was then drilled through 0.250 inch and cut to the length from the underside of the cap to the base of the slot to the back of the casing, plus 0.050 inch. Two of these pieces were prepared and degreased. The fit of one was checked, using the front plate to ensure that the bolt holes were aligned, before it was fluxed then soldered in place. When cool, the fit of the second one was checked before it too was cleaned, fluxed and brazed in position. Later a file was used to clean up around the brazing before making the two sets of nuts and bolts to complete the muffler. All it needed was a standard 2.50-inch nipple and a couple of coats of heat resistant paint.

Contact Peter Rooke at Hardigate House, Hardigate Rd., Cropwell Butler, Nottingham NG12 3AH, England •

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