A.S. Baker Company was based in Wisconsin and progressed from making rotary steam engines in the early 1870s, becoming The Baker Manufacturing Company in 1879. By the 1890s, large cylinder pumps, pine water tanks and rotary windmills were added to the production line. Monitor engines were first built around 1905 and within a few years an extensive range was offered, ranging from 1-1/4 HP pump engines to 15 HP horizontal engines.
These Little Monitor pumping engines were first made in 1911 and were extensively used in the Midwest, with thousands being sold. As a result there are many of them in restoration, although they are few and far between across the Atlantic! Production of all pumper engines ceased by 1944.
The serial number on this engine is 38,924 and it was probably made between late 1928 and early 1929.
The engine was removed from the pallet it was delivered on. Using an engine crane, it was lifted onto a small bench. This was not as easy as it sounds as there was no easy point to hook onto and the engine was top heavy and wanted to tip over. By wrapping a strap around it the lift was completed.
The first step was to remove the pump gear assembly and the eccentric. This could be looked at later once the main part of the engine had been overhauled.
There was a gib key with a head in the flywheel and a bolt to clamp the flywheel to the crankshaft. This bolt was removed along with the governor weight to clear the decks. After cleaning and oiling the short length of the crankshaft that was visible, the gib key was attacked with a curved key remover. There was very little shaft to clamp the remover tight against the key, and it proved unable to move the key.
The second attempt to move the gib key involved the use of twin wedges pushed together using a bolt. This proved easier to hold in place and the steady pressure of using a bolt rather than hitting with a hammer had its effect and the gib key started to move.
Despite using a wedge in the split hub to gently open it after applying plenty of lubricant, the flywheel did not want to move. After a few attempts to find the best position for a strong purchase that would not damage any components, two claws of a hub puller were fitted around the hub. When the puller was tightened the flywheel started to move, but even so it took the puller to drag it all the way off the crankshaft.
The cam follower was eventually removed after applying plenty of penetrating fluid and pulling and twisting it.
Attention then turned to removing the cylinder. The hand hole in the side of the engine was opened to reach the single clamping bolt for the big end, which was released. Fortunately, the engine was not seized and it proved possible to rotate the crankshaft to reach the nuts.
With the connecting rod free, the two nuts holding the cylinder in place were removed. The fuel line had already been released and the cylinder was lifted clear.
The piston required a little effort to remove it from the cylinder. The big end clamp bolt was hand tightened and a piece of wood was put through the bearing and used as a handle to pull it free.
The puller was then brought into use again to remove the cam gear so that the shaft holding the gear wheel on the pulley side of the engine could be slid out. However, the gear wheel appeared firmly attached to its shaft and was left untouched as it would be easy to clean as it was.
The bearing caps were then taken off and the steel washers that act as oil seals removed. The crank gear was stubbornly in place and yet again the puller had to be used to remove it. Then, twisting and pulling, the crankshaft was removed from the main engine casting.
The inlet valve and spring were removed, the valve being dropped through the hole for the exhaust valve cage.
The cylinder bore was then cleaned and measured, along with the piston. Surprisingly, there was minimal wear, with the widest part of the piston measuring less than 0.008-inch smaller than the bore. The rings were worn but there was still plenty of spring so they were left untouched. Similarly, there was wear to the ring grooves but only 0.002-0.003-inch and the grooves still appeared square. The decision was therefore made to leave the piston and rings alone, but to fit new rings if compression was inadequate.
After removing the cast iron fuel tank, the check valve and feed tube were removed and cleaned. The filler cap for the fuel tank was a standard 1-1/4-inch plug. Despite cleaning it with a wire brush and soaking it in penetrating fluid, the plug resisted all efforts to remove it. This included sliding a 5-foot long pipe onto the handle of a socket wrench. An impact hammer was also tried, but to no avail. Heat was not used as the alloy nametag is only a couple of inches away and there was no desire to risk damaging the tag.
After leaving it all to soak in penetrating fluid for another week the socket wrench and pipe were fitted again, the plan being to fix a heavy weight to the end of the pipe so as to keep a constant pressure on the plug. As we gave it all one last heave before fixing the weight a small movement was noticed, and gradually the plug came free. There was another plug underneath, and this proved relatively easy to remove. It was then possible to clean the inside of the tank using a variety of rods and scrapers to remove the rust before washing out with kerosene.
Cleaning and oiling
Once the initial grime had been removed from the fuel tank and main casing it became clear that there was a sizeable amount of old paint on the engine. In view of the amount of paint left on the base casting it would receive careful cleaning to preserve this paint as much as possible.
To start, the casting was put on a metal tray and a stiff paintbrush dipped in kerosene was used to clean off the majority of grease and grime. The grease had hardened with age and despite soaking did not break down easily, so a scraper was gently used to remove the top surface of this. We were careful not to touch any paintwork. The remains were then removed by using the rough side of a kitchen scouring sponge. Instead of rags to clean off the dirt, sawdust was rubbed on to the surface and this absorbed the dirty kerosene.
Once the whole casting had been cleaned it was given a liberal coating of automatic transmission fluid and this enhanced the original paint.
The cage for the exhaust valve was resting in the hopper of the engine when it arrived, along with the rusted head from its valve. The remains of the stem were rusted in place and the only way to remove it was to drill it out.
After drilling, the hole for the valve stem was first reamed with a 0.3125-inch diameter reamer, the original size of the valve stem. Reaming the hole, it became apparent that for a good fit an oversize valve stem would be needed, with a diameter greater than the original. The hole for the valve stem was eventually reamed out to 0.344-inch to give a good clean hole.
A new stem was turned to this diameter, less 0.002-inch to give clearance before being brazed to a disc of steel 1.50 inches in diameter and 1 inch long. This was then turned using a lathe to match the profile of the broken head before trimming the overall length of the valve to 5.312 inches. When finished, the valve was fitted in its seat and ground in using valve grinding compound until there was a perfect fit between the valve and the seat.
To finish the valve, a 0.125-inch diameter hole was drilled through the stem for the retaining clip, 0.250-inch from the end.
To complete this part of the restoration the threads of the studs to hold the valve cage were cleaned with a thread die. One of the studs was already loose so the seat was cleaned, Loctite applied and the stud refitted. Two nuts were tightened against each other on the stud and then a wrench was used on the top one of these nuts to tightly fit the stud in its hole. The nuts were then released and removed.
Fuel tank and mixer needle
The fuel pipe and check valve were removed, and despite some bad signs of rust the tubes were soon cleaned out and remained serviceable, although the down pipe was a little shorter than when new. The check valve was disassembled and cleaned and the dart was checked to ensure that it moved freely.
The mixer needle was missing, but with great help from Smokstak all the information needed was provided to make a good replica.
The needle part was turned first from brass rod to give a point with an included angle of 60 degrees before the thread of 0.3125-inch x 24 TPI (UNF) was cut for the overall length of the needle, 1.175 inches. To check the fit of the point in the valve the seat was covered with a thin coat of engineers blue using a small brush and the needle trial fitted. After slight adjustment to the compound slide the taper was re-cut and was then a good fit.
A knob of brass was turned with an outer diameter of 1 inch and a minor diameter of 0.625-inch, cut to a length of 0.250-inch and 0.3125-inch, respectively. After knurling the major diameter, this knob was drilled and the same 24 TPI thread cut, enabling the stem to be screwed in before brazing together.
A new spring was found that would fit over the needle and minor diameter of the knob and it was trimmed to length. Being zinc plated it looked too new so it was immersed in white vinegar overnight to clean off the zinc, finishing a dull gray color.
When it came to fitting both the fuel tank and the needle seat in the inlet, some adjustments were necessary to ensure perfect alignment. The mounting position of the fuel tank and the angle of the check valve to the fuel line pipes had to be adjusted in order that the seat for the needle sat flush against the air inlet when the retaining screw was tightened. Even taking care with the positioning of these parts there still appeared a small gap that air could enter by, thus diminishing the effect of the venturi. To overcome this a small O-ring was fitted between the seat and the inlet to seal it.
Big end bearing shell
One of the two shells for the big end bearing was in pieces. A replacement shell was to be cast in the big end so a core piece was needed along with end caps. A piece of steel was turned to the diameter of the big end journal to form the core, the ends being turned down to fit some end caps from another project.
To center the core in the bearing, some pieces of 0.1875-steel rod were used, super glued to the core to hold them in place. The core and end caps were then fitted to the bearing cap and held in place by clamps so that two pieces of 0.125-inch steel rod could be soldered to the end caps. These long rods rested on the flats of the bearing shell, thus holding the core and end caps level and in position. Once the solder had cooled the core was taken out and the temporary spacing pieces removed. The core and end caps were then greased before re-assembly.
A clamp was used to hold the end caps against the connecting rod and fireclay applied to seal any gaps and provide a dam along the rod supports to hold them in place.
The connecting rod was held in the vice with the top of the bearing level. The core was then heated with a propane torch while the pot holding the bearing metal was heating up. Once the bearing metal was hot enough to char a pine needle and soft solder would melt against the core, the metal was carefully poured to a level above the flat face of the bearing.
Once the metal had cooled, the core and end caps were removed. The pour looked good, with clean, even surfaces, so the surplus at the ends were sawn then filed to match the other half of the bearing. The bearing metal was also trimmed so that it was level with the flats of the clamping faces.
The connecting rod was again held in the vice so the new bearing could be scraped. Blue was applied to the big end journal of the crankshaft before fitting it and the high spots on the bearings were scraped. This was repeated until there was an even coating of blue on the bearing.
There was only a hole in the flywheel lug where the starting handle should be, so the first task was to bend a piece of 0.4375-inch steel to fit. This was accomplished by heating the rod in the brazing hearth then bending it to shape. A short length of steel tube was slid over the short end of the rod to hold it, while the remainder was held in the vice.
The rod was trimmed to length to fit the space between the spokes, then a hole drilled in the short end for the retaining pin. It was also necessary to file this end to a taper to give clearance from the flywheel spoke.
The other end was tapped with 0.4375-inch by 14 TPI threads so that a nut and washer could be fitted to retain the wooden handle. A steel washer was also brazed onto the rod just before the bend in it to stop the wooden handle from riding up to the bend. This might cause the handle to lock and result in possible injury to the starter’s wrist.
A scrap piece of beech was first drilled through for the 0.4375-inch rod before it was turned on the lathe and shaped for the handle itself. After light sanding it was given a coat of varnish and slid to the metal shank, being held in place by a nut and washer. The nut was not completely tightened, so that the handle could freely rotate. To prevent the nut from loosening over time, a touch of Loctite was applied to the threads.
The insulation on the wiper bar was well past its best, the rubber having perished and needing upgrading. The retaining screws were removed and the wiper arm that was then cleaned up.
Using the old insulators as a template some black plastic was used to make the two pieces needed as replacements to insulate the spring part of the wiper.