Mystic IHC Mogul Engine

By Staff
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The IHC Mogul engine at the time of purchase
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The cylinder/hopper removed
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The stripped main casting
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Using the hydraulic puller to remove the flywheel
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The broken gib key
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Cylinder head removed to show piston
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The Mogul after removing the fuel pump, eccentric and igniter trip
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Opened hand hole after removing four bolts to show big end bolts
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Fuel tank under crankcase
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The fuel tank removed
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Crankcase side plate, con rod and piston
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The IHC Mogul engine's crankcase
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Original, bent needle valves 
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Mogul's cleaned main castings ready for priming
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Mixer showing signs of wear, with bent needle valves
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New needle valve stems
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The IHC Mogul cylinder head
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Stripped mixer assembly
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Turning the brass rod to size
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Drilling the brass stem from throttle plate securing screws
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Starting to drill out the IHC Mogul's butterfly pivot rod
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Slitting the brass rod for the butterfly valve
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Parting off the new throttle plate
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The parts for the butterfly
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Bent rod to activate butterfly valve
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Test assembly of the butterfly valve

This IHC Mogul engine was imported into the UK in 2008 and I jumped at the opportunity to buy it. It was in need of a full restoration as it was missing the magneto, had no proper muffler and the mixer valve stems were bent. It looked as though it had been restored some time ago as the paintwork had been badly applied and was not the usual color you would expect. There was one saving grace — the skid looked original.

The serial number lists showed this particular engine (W13364) was built in 1916. The Mogul series of engines was built between 1911 and 1917, and was a predecessor of the Type M, which was first built in 1917.

Stripping the IHC Mogul engine

Starting the restoration, the first step was to strip the engine so that the previous paint job could be removed. First, I carefully scraped off a little of the paint in different areas to see if there was any original paint lurking underneath. Unfortunately the answer was no, not even any primer coat, and rust was beginning to form in several places under the paint, which had clearly been applied to an unprepared surface.

I removed the two oilers, one of which had already broken into two pieces before the engine reached me, then the greasers. Next, I removed the exhaust pushrod and then the exhaust pipe.

Removing the flywheels

When it came to removing the flywheels, the first problem occurred while using a tapered chisel to remove the gib key when the head came off the gib key on the muffler-side flywheel. This was despite already cleaning the shaft and applying a generous amount of release agent a couple of days earlier.

This meant I would have to drill out the key to extract it before removing the flywheel. The keys were made from 0.3125-inch wide steel so I center-drilled a similar piece with a 0.125-inch pilot hole before clamping it in the keyway and using it as a drill guide. Starting with this small drill size, I drilled a 3-inch deep hole in the key, and then opened up this hole in stages to just less than 0.3125-inch. After drilling out the key, I made several unsuccessful attempts to turn the flywheel on the shaft, with a wooden block positioned under the crankshaft web to lock it.

As the key had been destroyed by drilling and would not exert any pressure on the flywheel hub, it was safe to use a puller to remove the flywheel. It was difficult to position the hydraulic puller on the gear side as initially it was not possible to ensure the arms of the puller rested against the flywheel hub. However, it was possible to get some grip for the arms of the puller in the small area between the spokes, rather than on the spokes themselves. Eventually, the flywheel moved a little, and when it had moved enough I unbolted the gear wheel and pushed it back over the shaft so the puller arms could be rested on the hub itself for the final pull.

I removed the governor-side flywheel gib key and wheel without too much effort. The lock screw on the governor shoe was released and then its rod pushed forward.

Continuing to strip the engine

With the flywheel off I removed the fuel pump, eccentric and igniter trip before turning my attention to the piston and cylinder head.

Gaining access through the hand hole, I released the two retaining bolts for the connecting rod big end. In this case there were neither lock nuts nor retaining wire to hold the single nuts in place. Then I removed the big end cap along with the shims, taking care to keep them split into two sets.

After I removed the cylinder head, complete with mixer, I cleaned away the build-up of carbon on the cylinder wall above the piston. This enabled me to remove the piston and con rod from the front of the engine. Then I re-assembled the big end and shims in the same positions they were in when removed as an aid to later re-assembly. I soaked the piston in a tin of kerosene to free up the piston rings that were stuck in their grooves.

After unscrewing the five retaining bolts, I removed the crankcase side bearing plate along with the crankshaft assembly. The crankshaft bearings looked in good condition with no play, suggesting that they had been renewed during a previous restoration.

Now that the hopper and crankcase were stripped, I removed the two large securing nuts to release the hopper, making it easier to clean and paint the hopper and engine. Once the hopper had been removed, I removed the short lengths of pipe sticking through the casting for the fuel filler/return so I could unbolt the fuel tank to check it over. The tank appeared very solid, and I tested it by filling it with some kerosene. It was left to stand for a day before I shook the can to flush out any old fuel, grease and dirt and poured the kerosene out for disposal.

Using a combination of rotary file and sanding discs on a small angle grinder, I cleaned up the crankcase and hopper. I removed the paint and rust down to the bare metal, which I immediately gave two coats of red oxide primer to prevent the formation of further rust.


At some stage in transit the front of the Mogul engine had been damaged, with the mixer needle valves and the activating rod for the throttling butterfly valve being bent.

After I removed the cylinder head, I stripped the mixer to clean all parts and repair the damaged items. Most of the brass fuel lines were missing and needed to be replaced. The springs for the needle valves and the air intake baffle were in good, if not new, condition.

To repair the needle valves, I turned some 0.250-inch diameter brass to copy the dimensions of the originals and used dies to cut the 0.250-by-28-inch UNF threads. I cut a short taper for the tip totaling 45 degrees and used a steel lapping rod and grinding paste to clean up the seats in the mixer. I drilled out the stems from the old heads and then brazed the new ones in their place.

Cylinder head

I then stripped the cylinder head, removing the pushrod arm followed by the valve springs and valves. After cleaning, I checked the fit of the valves, specifically how well they seated. This was found to be good with no lapping necessary, indicating that this also had been corrected in the earlier restoration.

The throttling butterfly was another matter as the pivot rod was a poor fit, moving from side to side. Similarly, the old disc was a poor fit in its passage after I cleaned the accumulated dirt and rust from it using some emery cloth. The rusty pin holding the brass pivot rod to the spring and end plate proved difficult to drill out while still fitted to the cylinder head, so I drilled out the brass rod as a replacement would be necessary to improve its poor fit.

The outer seat for the pivot rod showed signs of rust or uneven wear, but the internal seat was satisfactory. I reamed out the outer seat 1/64 of an inch over size (0.328-inch) with the internal seat left unchanged. Next, I turned a section of brass rod to the inner and outer diameters of these seats, resulting in a step up to the larger size. I then set this rod up on the mill/drill to accurately drill two holes to be tapped for the valve plate for 0.125-inch by 40 securing screws. I used a 0.0625-inch slitting saw to cut a slot for the plate, and then finally I drilled the mounting screw holes on one side of the split rod with 0.140-inch clearance holes for the screws.

To make the valve plate, I turned steel bar to a diameter of 1-inch, which is the size of the bore. I then cut off a 0.0625-inch slice of this with a parting tool to form the thin plate. I placed this inside the slit cut in the pivot pin, marked the center of the two securing holes with a punch and then drilled 0.140-inch clearance holes.

Before removing the old pivot pin, I noted the alignment of the valve plate to the pin hole so the new one would be fitted the identical way. Next, I cut the new pivot pin to the size of the original, the remains of which were then removed from the pivot arm by punching out what was left of the retaining pin.

The only remaining cylinder head task was to straighten the activating arm, which was accomplished using heat and a vise.


The crankshaft big end journal had good fitting bearings, but the journal itself had a raised center section that could be cleaned up. The difference in the diameter of the journal was small, only 0.004-inch, but while the engine was stripped it could be polished out, rather than having to send the crankshaft away for regrinding.

I cut some emery cloth into thin strips, generally less than an inch wide, and then held the crankshaft in a vise so that the strip could be used to clean up the journal, taking care to work evenly around it. To achieve a good result using this method, patience is essential, and I checked my progress with a micrometer at regular intervals.

Big end bearings

I examined the bearings on stripping and the main bearings appeared tight. There was slight play in the big end bearings after cleaning up the journal, and on examination there were only three shims per side of some 0.060-inch each. To make future adjustment easier, I cut a number of new shims from different thicknesses of sheet steel so that it would be easy to make fine adjustments by removing a thin shim.


After some unsuccessful bids and waiting patiently for some 18 months, eventually I won a Type R magneto on eBay and later managed to locate a gear wheel to complete the engine.

The magneto appeared in good condition, so after a clean and some oil I rotated the shaft and there was little magnetic pull, so I would need to put the magneto on the charger. The thread at the end of the shaft was worn, but was just satisfactory. However, when the gear wheel later arrived and was fitted, problems emerged. The woodruff key was some 0.007-inch oversize and would not fit the slot in the gear wheel of 0.0625-inch. Without the key in place the gear wheel was a bad fit on the tapered shaft, and on closer examination I noticed that the shaft was bent as the wheel did not turn true.

After some thought I decided to set the armature on the lathe, cut off the threaded section and turn down the tapered section to form a spigot. I would turn a new tapered and threaded section to fit the gear wheel, before drilling the section to fit on the spigot.

I stripped the magneto by removing the pickup, then the four screws holding the end plate so it could be taken off, enabling the armature to be slid out. I wrapped a piece of tape around the windings to prevent the brush in the end of the armature being damaged.

I set the armature to run true using the fixed steady on the bearing journal as a slow speed and fine cuts would be used. Ideally, a collar would be turned to fit the bearing journal then the fixed steady arms could rest on the collar.

I measured the length of the threaded section and then cut it off, with the 0.500-inch tapered section being turned next. In this case it was reduced to 0.1875-inch, which importantly left a little of the original keyway in the shaft. The next step was to cut back 0.025-inch of the bearing journal, this being part of the journal that stuck out beyond the bearing.

To fit the spigot in the end of the armature, I turned a piece of 0.500-inch steel after first center drilling the end. I turned the first 0.375-inch from the end to 0.3125-inch diameter and cut a 18 TPI thread. A rough measurement of the taper inside the gear wheel showed a diameter of .375-inch increasing by .006-inch, so I used a dial gauge set over the compound slide to half of this. I formed the taper using fine cuts and continually checked its fit with the gear wheel, this being verified by coating the inside of the gear wheel taper with engineers blue.

The next step was to cut a slot in the taper for the woodruff key. In other cases I have found that a Dremel heavy duty cut off disc 0.0625-inch thick can be used if care is taken; of course a proper keyway cutter is better if you possess one. I achieved this cut by using the vertical slide on the lathe cross slide to hold the part, fitting the cutting disc arbor in a lathe collet.

I cut the taper/threaded section from bar with an allowance of 0.750-inch extra that would be used to hold it in the collet when reversed, the thread and the taper being on the inside. I drilled a 0.1875-inch hole to the correct depth, so that when the extra section was parted off, the replacement piece would be a sound fit on the spigot left on the armature. When I finally parted the machined part, 0.025-inch of the full 0.500-inch diameter was left. This would stop the new part splitting along the key slot and also provide a rear shoulder in case the gear wheel went on too far when its retaining nut was tightened. If it did, the shoulder would stop it from pulling on the armature shaft.

The reason for leaving part of the old keyway on the spigot was to first provide a reference point so the keyway in the new piece would be correctly aligned and secondly to allow the key to rest in it to stop the new piece twisting on the shaft. I followed this approach so the repair could be fixed with Loctite. An alternative would have been to use low-temperature silver solder to fix the new to the old. However, even with putting a large, tight-fitting and heavy heat sink around the bearing, there would always be the danger that the windings/insulation might get hot and damaged.

Before fixing the new piece in place I made and test-fitted a 0.0625-inch thick key, ensuring that it rested in the remaining part of the old slot. I cleaned the new taper and the spigot, and after applying Loctite the repair was allowed to cure overnight before I cleaned out the slot and reassembled the magneto. The magneto was then given two, one second bursts on the magnet charger, which made it far more difficult to turn the shaft. I fitted the gear wheel and there was no noticeable wobble when it turned.

To complete the ignition I cut a length of covered wire and then made a brass clip to fit the lead-out tower. I made the clip by cutting a slot in some thin brass, then hard-soldering a short length of brass tube to it. I carried out final shaping with a file before soft-soldering the igniter wire in place and fitting a piece of rubber insulation. At this stage it was not clear how good the magnet might be, and if it proved difficult to start the engine this clip would make it easy to connect to a battery/coil setup and then quickly remove it and fit it to the magneto tower.

I needed two bolts to mount the magneto to the bracket, so I measured the thickness of the bracket and depth of the holes to ensure that the bolts would not bottom out and damage the base of the magneto. I cut the two replacement bolts 0.125-inch shorter than the combined measurement.

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

For more step-by-step projects by Peter Rooke check out Will This John Deere Model E Run Again?

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