By Staff
1 / 15
Peter Rooke’s latest project, a 3 HP IHC Model M.
2 / 15
Using a hydraulic puller to remove the pulley.
3 / 15
The replacement nuts and bolts made on the lathe.
4 / 15
Using a guide to drill the flywheel key.
5 / 15
Rusted cylinder head showing sawn rods.
6 / 15
Slitting the brass pivot for the intake butterfly.
7 / 15
The replacement brass arm for the butterfly fitting.
8 / 15
The engine casing after stripping, ready to start restoration.
9 / 15
The new butterfly assembly with homemade spring and rod.
10 / 15
The components for the new exhaust pin.
11 / 15
Turning the new valve head after it was brazed to the stem.
12 / 15
Drilling out the valve guides.
13 / 15
The new inlet valve, the repaired exhaust valve and the lapped seats.
14 / 15
Completed pivot pin and tidied rocker arm.
15 / 15
The pushrod support brazed to the cylinder head before repairing its crack.

I had mentioned to an engine friend that I had
considered purchasing an IHC M for restoration, but thought the
price was too high, so I left it. A week later he telephoned to say
he knew of another 3 HP engine, but that it was very rusty and if I
was interested he would send me some photos. He was not

When I saw the photos it was in appalling condition, just as I
like them, and better, the price was reasonable. Even more good
news, he had to travel to Dorset, a 400-mile round trip, to collect
another engine, so he could pick mine up for me. Two weeks later, I
travelled a short distance to his engine store to collect my
engine, which we man-handled onto my trailer for the journey

Once home I used a chain hoist to lift the IHC off the trailer
and onto rollers, so I could move it around the workshop. For the
first time, I was able to examine the engine carefully. Everything
was there including the crank greaser, but the oiler was long gone.
I later found the broken lower section in dirt at the bottom of the
water hopper. From the serial number it was possible to date the
engine from 1920, fitted with the more common overstrike igniter.
It soon became apparent that while a lot of work would be involved,
the restoration should be fairly straight forward. There are lots
of parts and information available for this engine, although they
are not too common here in the United Kingdom.

Before stripping the engine, it needed some cleaning, so I
rubbed it with a wire brush then moved it onto a plastic sheet and
liberally coated it with oil. I left the engine for a couple of
weeks and in that time coated it once or twice a day with oil.
Given the condition of the engine, I guessed it had been stored
alongside fertilizer sacks, and the dust from those had covered the
engine and advanced the rusting process.


To start the stripping process, I removed the brass pipes and
their fittings, as they are difficult to replace. Being brass, they
had not rusted in position.

The flywheels and pulley were going to be a problem in view of
the amount of rust, so they were liberally coated with penetrant.
The cover for the gib key and the crank grease cup were removed,
the former by drilling out the screw. The remains of the three
other grease cups were removed – they all needed replacing.

To prevent any damage to the governor, the ring was unbolted
from the flywheel. Fortunately, it had been covered in grease and
the securing bolts had not rusted and were loosened with a wrench.
The weights were immovable; the springs had long since rusted away
so the pivot pins for the weights were cut through with a hacksaw
and a miniature cutting wheel.

The governor fork was rusted firmly in place and the rod to the
mixer butterfly could not be moved. It was cut off either side of
the fork, the remainder being drilled out of both the fork and
supports on the lower bearing casing when the engine was

Removing the pulley and flywheels

Removal of the gib key locking the pulley was complicated as the
pulley rim extended over the end of the crankshaft, which made it
impossible to remove the key with a wedge and hammer. Rather than
weld a rod to the end of the key and use a slide puller to pull it
out, I decided to drill the key as everything was badly corroded.
It was also necessary to drill the locking screw, which was stuck
fast and didn’t budge even using an impact driver. The exposed
areas of the crankshaft, including the keyway, were cleaned with a
file and emery cloth to remove all ridges, nicks and rust. The
crankshaft was covered with a liberal coat of penetrant. Once the
key had been drilled, the pulley was twisted off and the remains of
the key removed.

The keys, flywheel hubs and crankshaft had been soaked in
penetrant for a few days after first shocking the keys with a
hammer and brass drift. The key heads were squared with a file and
a homemade key drift clamped to the crankshaft to remove the key.
As expected, the heads sheared off and, again, I had to be patient
and drill out the keys.

To drill the key, a 5/16-inch hole was drilled in a piece of
7/16-inch diameter rod, the width of the key. I chose this size of
drill because I had a newer long shank drill, which was accurate to
start a pilot hole. I prefer to start small in case I hit a problem
and need to straighten the hole. If necessary you can soft solder
an ordinary length drill to an extension piece to get the required

The drill guide was clamped to the crankshaft, tight against the
broken key. The secret of deep-hole drilling is to keep the drill
bit well lubricated and to keep clearing the swarf, by frequently
withdrawing the drill. Firm, even pressure was applied to the drill
and plenty of patience was needed to allow the drill to do its work
without forcing it. Once the pilot hole had been drilled, it was
opened using progressively larger drill bits to a fraction under

Efforts to twist the flywheel and break the remains of the key
failed, so the hydraulic puller was used. Even this was a struggle,
so I had to hit the hub of the flywheel with a hammer and drift
while it was under tension from the puller. There was a resounding
crack and the flywheel started to move. Care was taken throughout
to ensure any pressure or force was only applied to the flywheel
hubs to prevent any possibility of breaking the flywheel

Removing nuts and bolts

The key to removing rusty nuts is to have a wrench the correct
size for a tight fit. Unfortunately, the hexagon sides to the nuts
were, without exception, badly corroded. The object in these cases
is to prevent damage to the studs, thereby complicating the
restoration by having to replace them. Where there was room, the
sides of a nut were cut with a hacksaw or removed with a small hand
grinder. For the more difficult positions, the nuts were split with
a cold chisel and lump hammer. This, of course, meant that a large
number of nuts and some bolts had to be replaced, meaning that
several days were spent making replacements.

As mentioned already, the governor rod was rusted solid in the
fork holder and the cylinder head. Similarly, the exhaust pushrod
was immovable. The rods were all sawn through so the cylinder head
could be removed. At this stage, I noticed the exhaust rod support
was broken and would have to be repaired. The remains of the rods
refused to move easily despite soaking in penetrant, so they were

Once the mixer and cylinder were removed, the bolts securing the
bearing caps were unscrewed and the caps were taken off. Care was
taken so that the bearings were not damaged and the shims were
stored safely until needed. The crankshaft, gears, connecting rod
and piston were removed. Externally, the engine was in a bad state,
but internally, there were no problems; the bore, piston rings and
bearings were all perfectly serviceable.

Finally, the fuel pump eccentric and follower were removed and
the engine turned over to get at the fuel tank, which was just a
rusty shell.

The IHC casting was cleaned using a wire brush and scraper, and
the threads on all studs were cleaned using the correct sized die.
Internally, all parts were washed with kerosene to remove years of
grease and grime. As the inside of the engine was in good
condition, the cylinder sleeve seal was not changed. This later
proved to be the correct decision as there were no leaks when the
hopper was eventually filled with water and the engine run.
Earlier, the engine block had been taken outside and pressure
washed to remove all mud from inside the water hopper. At this
stage, the remains of the oiler and feed tube were found wedged
down the side of the cylinder.

Once the engine was in pieces all parts could be examined and
decisions made on what to make and what to buy. While just about
everything needed could be purchased, numerous items could be made,
which is part of the challenge when restoring an engine. I decided
that I would purchase a new fuel tank, grease cups, some pipe
fittings and springs from Hit & Miss Enterprises, but would
make nearly everything else. A replacement magneto would also be
needed as the original was beyond repair.

Cylinder head

The engine cylinder head would require extensive restoration
with the majority of parts requiring replacement. The connection
pipe to the muffler had rusted so badly that it would have to be
replaced, but the elbow, while badly corroded, was passable. To
re-duce any risk of damaging the cylinder head, no attempt was made
to move the elbow. But in order to replace the pipe, it was
necessary to cut the muffler with a hacksaw, then remove the
remains of the pipe by sawing it lengthways before splitting.

The operating camshaft for the broken butterfly was removed by
cutting the brass pivot pin. The spring had long since disappeared
and when trying to remove the activation rod, part of the camshaft
disintegrated. After cleaning the body of the camshaft a new plate
was fashioned and brazed into place with a new pivot pin for the
link to the governor. A piece of 5/16-inch brass rod was slit and
screw holes tapped for a new butterfly, which was made out of
1/16-inch sheet. The size was marked with a compass before
carefully filing it to fit, taking care to get it exact. The holes
for the mounting screws were drilled, then opposite top and bottom
edges of the butterfly were tapered for clearance to allow it to
close fully.

The original adjustable link to the governor rocker shaft had
virtually rusted away so a replacement was fabricated from pieces
of steel to match the estimated dimensions of the original. A
return spring was made to complete this part of the

While the nut holding the rocker arm pivot eventually came off,
the pin didn’t move, so the head of the bolt was cut off and a
press was used to push the remains from the top.

The governor rod and exhaust pushrod were drilled and finally
the valve stems were sawn off close to the top of the guides.
Again, they were seized solid and it was necessary to set up the
cylinder head on the drill table and drill through the stems. A
file was used to clean the remains of the valve stems, cutting
slightly into the top of the valve guides so the full diameter of
the rusted stems was visible. This enabled accurate use of a center
punch to mark the center before drilling a pilot hole through the
stem. Drill sizes were gradually increased until the hole was close
to cutting into the wall of the valve guide when the remains of the
stem were pressed out. The holes in the valve guides were tidied
using a 3/8-inch hand reamer. The exhaust valve head was
salvageable, but the inlet was so badly corroded the whole valve
was scrapped.

New valve stems were made from some 3/8-inch drill rod. For the
exhaust valve, the remains of the old stem were drilled out of the
head, which was brazed to a new stem. A completely new inlet valve
was made using a disc of steel for the head and drill rod for the
stem. They were brazed together and the lathe was used to profile
the head to match the original, although it was made a fraction
wider. The inlet and exhaust valve seats were corroded and as the
damage was extensive, the seats were first cleaned with a file and
the heads ground using valve grinding compound.

The repair to the rocker arm pivot was not quite straight
forward. The original appeared to have a floating sleeve between
the threads and the head of the bolt, so the only way to duplicate
it was to fabricate a replacement. Taking dimensions from the
original, the various components were machined and the sleeve and
stem were given a thin coat of oil before being assembled and the
bolt head brazed on.

The final problem with the cylinder head was the guide for the
exhaust pushrod, which had broken. To start the repair, the guide
was Super Glued back on to the casting in its correct position. Two
1/8-inch holes were drilled lengthways through the broken piece
into the main casting and small escape holes were drilled in the
main body to allow any air trapped to escape when brazing. Once the
holes were drilled, the piece was broken off by exerting lateral
pressure and all vestiges of the Super Glue removed by cleaning
both sides of the joint with a small grinding point.

As the cast iron was badly oiled some flux was applied and the
area was gradually heated, bringing it to brazing temperature for
the flux to draw out any oil and impurities. It was necessary to
repeat this stage three more times.

When satisfied that the metal was clean, the tie-rods were
fluxed and inserted, the faces fluxed and it was all held together
with a small clamp, ready to braze. As normal with cast iron
repairs, it was heated slowly and the heat maintained when
finished, to allow the temperature to fall gradually for slow
cooling. The flux allowed the braze to flow around the tie-rods,
locking them in position and strengthening the joint.

To repair a crack in the head of the guide, the pushrod hole was
enlarged by drilling it 1/8-inch oversize and a sleeve turned to
fit inside making it slightly longer than required. It was drilled
to the diameter of the pushrod. The crack was cleaned with a file
and impurities removed using the heat and flux method. After
cleaning everything again with emery cloth, more flux was applied
and the sleeve brazed into the head and finished by drilling a new
lubrication hole and filing the ends flush.

Read part two in the next issue, restoring the fuel pump and

Contact Peter Rooke at: Hardigate House, Hardigate Road,
Cropwell Butler, Notts, England, NG12 3AH;
peter@engineerpeter.co.uk • www.enginepeter.co.uk

Gas Engine Magazine
Gas Engine Magazine
Preserving the History of Internal Combustion Engines