Restoring a 1-3/4 HP Monarch, Part 4
By Peter Rooke
Peter Rooke's fully restored 1-3/4 HP Monarch antique gas engine badged by Nelson Bros.
Photo by Peter Rooke
The following is Part 4 of a four-part series documenting Peter Rooke’s restoration of a 1-3/4 HP Monarch badged by Nelson Bros. Read Part 3.
Skid The skid for this engine is fairly simple and a copy was made from sizes taken from one seen at a local show, where the exhibitor mentioned that his cart was made to original dimensions. All that was needed were two side pieces, a couple short cross members and some tensioning bolts.
Fortunately there was some 4- by 2-inch soft wood in the garage, left over from a building project many years ago. The wood was of good quality being fairly dense and not like the soft rubbish that you generally get nowadays.
The two long spars were cut first, 2 inches longer than the required length of 38 inches. This was deliberate as there was more than enough to do this and it provided a safety margin in case the timber was dropped and the end damaged.
The timber was first put through the planer to clean it up and the positions of the engine mounting bolts were marked. The step in the height at the front of the engine, which was 1.250 inches lower than the main section, was marked out. When marking out, allowance had to be made for the extra inches at both ends. A piece of 3.25-inch diameter steel was found to mark out the curve where the height changed and then the surplus was sawed off. A rotary sanding drum was used to complete the curve and next, before doing anything else, the side pieces were given a quick rub with sandpaper and a coat of varnish to seal the wood while it was still clean. It is very easy to get black marks on untreated timber and it takes a lot of effort to clean it again!
There had to be a 6-inch gap between the two main spars, so two 3.50- by 2-inch spacers were cut, 7 inches long and positioned so that there was a 0.250-inch gap on top and bottom. These were then inset into each side by 0.50 inch. The easiest way to cut these recesses was to use the milling machine before tidying up the corners with a chisel.
Four 0.312-inch holes were then drilled through the sides for the tie bolts. It is preferable to leave a gap between tie rods and the spacing timber to stop dirt and moisture collecting, so the spacing timber was drilled 0.50 inch.
Before finishing the skid four holes were drilled for the engine mounting bolts, the underside being recessed 0.750 inch for the heads of the coach bolts.
Finally, the 1-inch buffer at each end of the long spars was cut off and all the timber sanded again before it was given three coats of varnish over the next few days. Having made the fuel tank with a long lip on each side it was necessary to cut a groove along the inside of the long spars. This was made on each side where the height changes and enables the tank to slide right back and rest against the cross piece.
The base of this engine casting is open, and with the drip- feed oiler right at the crankshaft end of the cylinder there is the inevitable seepage of dirty oil through it. With a cart, it is possible to slide a drip tray between the wheels, but not when running the engine on a small skid like this one with no wheels.
Incidentally, the rear location of the oiler on this engine has an advantage as there is minimal blowback, so a lubricating oiler can be fitted rather than one with a pressure relief tube.
The last thing that you want to leave at the show site is a puddle of dirty oil on the ground, so a drip tray was needed. The cross members on the skid had already been set 0.250 inches shorter than the side pieces, so a tray was formed from some 0.020-inch thick sheet steel with a 0.183-inch lip around it. The tray measured 6 inches wide by 17 inches long and slid underneath the engine casting, resting on the two cross members of the skid. The lips on the tray were bent using the same techniques described in the previous article on building a fuel tank. Once the lips were formed, the four corners were soldered to prevent leakage of oil. This small lip proved sufficient to hold the oil for a day’s running, and it is easy to remove the tray when the engine is rested should it be required to drain the oil into a container for proper disposal.
The tray was long enough so that 0.750 inch protruded at the back of the engine casting when in the closed position, providing room for a finger to slide it out for cleaning.
The first question to resolve was determining the original color of the engine, particularly as there seems to be a general lack of information about a lot of these contract engines. When stripping the engine, I discovered a hint of the paint color behind the name tag, which appeared to be a red tinted brown. However it must be assumed that this color had aged considerably so the original might be a lot lighter.
These engines were built to a price and the original finish was a little rough with any marks and pitting in the castings left unfilled before it was painted. With this in mind, apart from smoothing a couple of large blemishes in the casting, they were left untouched and the surface left rough before giving it a couple of coats of red oxide primer.
In the meantime I had tried to match the specks of paint to a sheet of colors produced by one of my computer photographic programs, and after trying several options by lightening the color, I had what I thought was a good match. The end result and the color used matched the general description of a “rusty brown” that another enthusiast had mentioned.
I had encountered problems with an earlier restoration with the enamel paint not being fuel-proof. After a bit of experimenting I discovered that in England, International Paints Japlac is reasonably fuel resistant, providing it is allowed to cure properly. It also gives an excellent finish, brushed or sprayed.
As usual, I obtained a few small tins and then experimented mixing small quantities to see if I could achieve the color I required. Eventually, I ended up mixing brown and red to get the shade of brown I wanted. The main body of the engine was given several coats of this enamel paint.
As I had some extra black heat-resistant engine paint, the cylinder head, mixer and muffler were given two coats.
I was led to believe that the lining of the engine followed the pattern I had seen in some old photographs with yellow paint being used, so out came the lining kit. I cheated and used tape to set out the straight lines so that I only had to paint a small amount freehand. A small pot of lining paint was mixed to a yellow color that looked right against the brown of the engine block, before the taped, straight lines were painted. Once these were thoroughly dry the outline of each bend was drawn with a wax crayon before being painted freehand. If a mistake was made it was simple to wipe the wet paint away and start again.
Setting up the engine: Pushrod
Once all painting had been finished, several days were given to allow the paint to completely harden to improve its scratch resistance. The engine block was then given a good covering with wax polish and buffed, which would help protect the paint.
Two new rivets were made from brass and the original name tag was then fitted.
The first step in re-building was to refit the piston and connecting rod, the rings on which had only been cleaned and not replaced. The connecting rod had already been trial fitted to the crankshaft on the work bench so that the shims could be made and adjusted, as this makes it easier to assess the fit. Similarly, the con rod shims had been cut and fitted when the crankshaft was free to turn without any drag from the piston or con rod bearings.
The gear was fitted to the crankshaft followed by the cam gear using the punched marks to set the meshing point. After clamping the engine casting to the work bench to prevent it from toppling over, the exhaust side flywheel was fitted, although the gib key was not fully driven home at this stage in case the wheel had to be removed again. This enabled the crankshaft to be easily turned over to check the valve and igniter timing.
The cylinder head was fitted on top of its gasket and the retaining nuts tightened, followed by the pushrod. It was soon apparent that when the engine was turned over the punch marks on the gear wheels were not correct, because it was impossible to adjust the rocker arm so the opening and closing of the exhaust valve occurred at the recommended positions. The exhaust valve should open between 35-40 degrees before bottom dead center and close with the rocker arm starting to leave the valve stem when the crank pin is 5 to 10 degrees after top dead center.
Some trial and error fitting followed, changing the meshing point of the gears and moving the adjusting screw on the rocker arm.
Once the settings appeared correct, the new meshing points were center punched and all old marks ground off.
Setting up the engine: Igniter and magneto The first task with the igniter and magneto was to move and lock the adjustment screw on the electrode arm until it just touched the push finger.
When the magneto bracket was bolted on the engine it was soon apparent that the trip arm would not make good contact with the trip finger when the cam was set in the “run” position. The easiest way to resolve this was to put a washer on each of the four magneto mounting studs to lift the magneto on the bracket.
To time an igniter, the engine crank should be first moved to 40 degrees before top dead center. The adjustment is calculated at 8 degrees for each 100 RPM, and this engine was designed to operate at 500 RPM.
Move the timing lever to the front of the engine – the running position – then cock the magneto using the tripping lever. The length of the pushrod should then be adjusted until it just touches the push finger, with the wedge clear of making any contact with the roller. The lock nut on the pushrod should be tightened before the wedge is moved forward until it just lifts the end of the pushrod over the trip finger. The set screw and lock nut for the wedge should then be tightened.
Remove the tripping lever and then turn the flywheel a couple of times to check that the igniter trips at the correct timing. If not, repeat this adjustment exercise.
Setting up the engine: Governor
Once the timing had been set, the speed change lever, detent and governor collar were fitted, followed by the flywheel weights and flywheel. When fitting the flywheel, care should be taken to ensure that there is sufficient room left between the flywheel hub and crankshaft gear for the governor collar to move and engage the detent. Once happy with the position of the flywheel, the gib keys on both flywheels can be driven home, firmly but not with excessive force.
The speed change lever was set to the right hand position for normal running before adjusting the springs. The original governor springs had long since disappeared, so the fitting of new springs would be a matter of trial and error. A pair of springs that looked right were taken from the spares bin but later, when the engine was running, it was found that they were a little too firm as the speed was well over 500 RPM. Some weaker springs were found but with these the engine ran too slow! The length of these springs was gradually reduced by trial and error until the engine ran around 500 RPM, the original factory setting. Moving the speed change lever to the left hand position would reduce this speed by some 75 RPM.
Setting up the engine: Mixer and running
The fuel pipe was connected to the mixer and some gasoline was poured into the tank.
All grease cups were filled and screwed down ensuring grease had been forced into the bearings, and the oiler was filled and set to drip at 10 to 15 drops per minute. All moving parts and oil points were given a generous coating of oil, the drain cock was closed and some water was poured into the hopper.
The instructions for this engine mentioned that the needle valve should be 3/4 opened and the choke plate closed to be ready for starting. After ensuring that the igniter was set to the start position, the engine was turned over and it fired but it soon stopped again, even with the choke plate being quickly opened.
What followed was a period of trial and error to identify the best setting for the needle and choke. Even when warm, the engine would cut out when the choke plate was fully open, and it soon became apparent that the engine ran better when the choke plate was only 1/4 open and the needle valve shut down to half open. I guessed that this was a similar problem that I had experienced from time to time with other engines, and that the air flow needed to be reduced for no-load running. This had been achieved with other engines by placing some form of restriction in the air intake, to increase the air flow over the needle valve to atomize the fuel. This could be by using the choke plate, or by inserting a tube or disk with a smaller hole.
If the engine is coasting then the fuel/air mix is only being drawn in after a prolonged period of sucking only air into the combustion chamber through the exhaust valve. The air flow through the mixer will fall rapidly as the engine speed reduces, and when the engine wants to fire again the mixture will not be rich enough. Two or more cycles may be needed before the mixture is right, during which period the engine could stall. Restricting the size of the air intake increases the air flow over the needle valve and the atomizing of fuel, reducing the risk of stalling.
Once the engine is placed under load and begins firing more frequently the choke plate can be opened and the fuel needle returned to the normal setting.
When running, there was some blow-by caused by the pitting in the bore. This might have contributed to the stalling problem as the force at which the air is drawn through the mixer was reduced. Every engine is different, even among the same make, and not all need the size of the air intake reduced.
Once the settings for the mixer and governor were finalized the engine was allowed to run for a couple of hours to bed in the bearings, ensuring that all moving parts were kept well oiled or greased. This was when I took the opportunity to hold an abrasive block against the rims of the flywheels to clean them up, taking care to keep gloved hands well away from any moving parts, particularly the starting handle, which does not always fold in and can give a nasty knock. Once running in had been completed all nuts were checked over and re-tightened, particularly the cylinder head, igniter and all bearings.
The flywheels ran true, showing that the crankshaft straightening earlier in the restoration had proved successful.
The fuel tank was then drained and the engine cleaned with all exposed metal surfaces lightly oiled before putting the engine in the shed, ready for the start of the show season in a few months time.
The final task? Prepare, print and laminate the fact sheet for the engine, ready for its first outing at an engine show.
Contact Peter Rooke at Hardigate House, Hardigate Rd., Cropwell Butler, Nottingham NG12 3AH, England • firstname.lastname@example.org • www.enginepeter.co.uk.