VBS ENGINE

By Staff
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118 N. Glenwood Ave., Orlando, FL 32803.
georgefair@earthlink.net

I had just put the finishing touches on my ‘basket case’
engine. It looked great and ran well, but this was the middle of
May. In Florida, most of the swap meets are in the winter, when the
weather (normally) is excellent for outside engine shows. The long
hot summer is almost here, and I have run out of rusty iron to
clean up while sitting in the shade of the big oak tree in my back
yard. My wife reminds me that help is needed at chuech to build a
boat for Vacation Bible School. The VBS teachers had empty
refrigerator boxes for construction material. I worked on the
project with others, but my mind was on my next engine. I had some
ideas for building an engine, but with my limited selection of
power tools, it would be a challenge. Some of my self induced
restrictions were to use scrap and used parts with no welding,
milling or lathe turning. The only power tools that I had was a
drill press, a belt sander, a portable electric drill and a Dremel
tool. I had no plans or drawings.

‘Curbside Parts Supply’ (trash piles) is my source for
angle iron. Just before the metal was put on the trash pile, it was
recognized as a bed frame, but now it will be a frame and braces
for the engine. Perhaps this project will help clean up some my
accumulation of junk.

On Saturday morning I went to R & S Performance, a diverse
Volkswagen repair shop, to visit with Big Daddy and Scooter. I told
them of my ideas and asked if they had anything in their scrap
barrel that I could use. They offered a head with valves, two
connecting rods, two wrist pins, one cylinder and a piston complete
with rings. At last I had a project engine to work on.

The dual port head was from a 1600cc VW, and had a crack from
the spark plug hole to the intake valve on one cylinder. A hacksaw
was used to get rid of the cracked half of the head, while
carefully leaving the intake port on the ‘good side’ in
tact. The valves were removed and new retainers that would work
with weak springs were fabricated out of copper tubing and inch
copper sweat joint caps.

Three of the cooling fins were hack-sawed off on the cracked
side of the VW head. This part had the flat surface needed to give
the bottom end of the cylinder a flat mounting surface, and
functioned like a large washer. The bottom of the cylinder was
supported with angle brackets. The VW head was supported with a
short piece of aluminum channel, and would be mounted to a frame as
soon as I could determine the overall size.

It is always interesting to see a lot of exposed moving parts on
engines, so I elected to go with a chain driven overhead cam. A
local surplus house had a pair of mounted bearings that looked like
they were ready to come out of retirement to support my project.
Some aluminum wheels were also purchased to mount a sprocket that
was salvaged from a 10 speed bicycle that I got from the
‘Curbside Parts Supply.’ The 28 tooth cam sprocket was
mounted so fine adjustment in valve timing could be made by backing
out the screws and rotating the 28 tooth sprocket; the smaller 21
tooth sprocket was only used to clamp the 28t sprocket like a big
washer. The stationary ignition contact, a small screw, is
insulated by nylon shoulder washers, and the rotating half of the
points is a piece of brass shim stock mounted on a homemade
rotating mount on the grounded camshaft.

The camshaft bearing location was selected so the camshaft would
be over the exhaust valve. One side of a strap hinge was hack-sawed
in half, and two elongated holes were drilled and filed on the
‘short half.’ There was a sheet metal mounting boss on the
VW head, and another hole was drilled and tapped nearby for the
mounting of the old hinge, which is now the cam follower. The
elongated holes will allow for valve clearance adjustment. A steel
gear that had a good mounting hub was purchased at the surplus
store, and was used to mount the lobe for the exhaust valve. A
large steel washer was cut in half and mounted to the steel gear
with two bolts. A belt sander was used to grind the cam to start
opening the valve at 145° ATDC and close by 5°ATDC. The maximum
lift was just over inch. The intake valve would operate on
atmospheric pressure

The main connecting rod caps were removed and two connecting
rods were bolted together, with grease cups to lube the wrist pin
and crank (another wrist pin). A Dremel tool was used to grind a
grease groove in the bearings. Scooter gave me an old VW muffler I
cut it up to get a short exhaust pipe and a muffler flange that
would be used for an intake manifold hold down clamp. The intake
manifold is a short inch pipe nipple and a inch floor flange. I was
beginning to dream about the sound of hearing it fire for the first
time.

Old lawn mowers with Briggs & Stratton engines can often
found at ‘Curbside Parts Supply.’ A mower that I recently
picked up would run, but it seemed tired. I really hated to
amputate the non essential parts with my hacksaw, but I made it
quick and painless. The ‘top’ half of the engine was cut
off. I used the crankshaft with two key slots on one end (mounts
for my crank and cam sprocket), the flywheel and the empty
crankcase housing (main bearings). I really needed a horizontal
shaft engine for my venture so I mounted this modified vertical on
its side, using more angle iron. A PVC pressure test plug was used
for a removable plug in the old cylinder bore; this plug is easily
removed to check the oil that lubricates the main bearings.

The crank pin is a ‘ bolt run thru a VW wrist pin and a
piece of steel flat stock. This is bolted to a brand new, (the most
expensive single part; $5.99) heavy duty lawn mower blade adapter.
The stroke is 3’, which is long for a VW. To lower the
compression I would locate the crankshaft so more piston skirt
would be exposed. A 14 tooth sprocket from a 10 speed bicycle
(courtesy of ‘Curbside Parts Supply’) is mounted on a
modified light duty lawn mower blade adapter, and is locked onto
the PTO location on the Briggs shaft.

The old Briggs carburetor had a lot of features that I thought
could be eliminated. So I removed the fuel pump, choke and primary
pick-up tube. I drilled, tapped all nonessential passages. The
surplus house had some plastic check valves I soaked one in acetone
for a couple of days and it still worked, so gasoline probably
won’t affect it. My gas tank is a baby food jar, it’s
probably not OSHA approved, but it eliminates the need for a gas
gauge.

A VW bus brake drum, a 4 inch v-belt pulley and a 36 tooth
bicycle sprocket were bolted together, then bolted to the Briggs
flywheel and also secured to the Briggs crankshaft with 10-32 bolts
that extend into the shaft. That would sure mess up your day to rev
the engine up and launch the flywheel. Using the angle iron from an
old bed frame I made a 24×14 inch engine frame, corner braces and a
couple of braces to mount the sub-assemblies and used
3/16 inch pop rivets to secure the frame. I
was amazed how fast the assembly went with the pop rivets.

A modified bicycle derailer from ‘Curbside Parts Supply’
was used to take up the slack in the chain. I bought a pair of
roller skates at a church rummage sale for 50 cents. I mounted one
wheel in my drill press and cut a groove in it with a rat tail
file. A little hacksaw work to cut it down in width and some time
on the belt sander gave me an idle wheel with ball bearings. Plus I
have seven spare wheels each with 2 sets of ball bearings
that’s less than 7 cents per idle wheel.

You know if an engine will run just a little you have a starting
point to begin adjusting everything to get it running better. A
piece of duct tape was placed over the carb intake to choke it and
I turned the flywheel nothing. By now I have more time into this
engine than I would care to admit. I wrapped a starting rope around
the modified v-belt belt pulley and pull again still nothing. We
have all been there before, perhaps a little help needed now, as
silently you say: ‘Please, let it fire just once.’ I
wrapped the cord and pulled BANG! Well, I got what I wished for, it
did fire once. The frame wasn’t stiff enough and flexed,
allowing the piston to come out of the cylinder just enough to
expose two rings. The exposed rings expanded but the flywheel had
enough momentum to keep turning. It bent some of the angle iron
mounting points and sprung one corner of the frame up 6 inches and
bent the inch camshaft. Be careful, be very careful of what you ask
for.

Scooter gave me another set of used piston rings and suggested
that I mount my frame to something else, like a sub-frame. It took
about two weeks before I could get any interest in working on the
engine after the ‘Big Bang.’

Wood for the sub-base is a plywood sink cutout. I glued and
screwed 2×4 pine around the edge to make it as stiff an possible.
Two 4 foot pieces of 2x4s were used to straighten the frame. All
pop rivets on it were drilled out and replaced with flat head 10-32
screws or -20 bolts. Someone offered to weld my frame for the cost
of material. That was tempting, but I would have to deviate from my
original ground rules of no welding, turning or milling. Perhaps
I’ll consider that generous offer on my next engine. The
camshaft was increased to 3/8 the mounted
bearings were still a little oversize so new bushings were made
with a couple different sizes of thin wall brass tubing. Other
components on the overhead shaft were drilled out to
3/8 I shortened the throw from 3′ to
2.5′ and remounted the Briggs crank closer to the VW head. My
compressor ratio is about 5:1. More angle iron braces were added,
and the original base was bolted to the new wooden sub-base.

A small 9 volt NiCad battery and a Ford buzz coil was mounted on
the engine base, and the baby food gas tank was filled with 40:1
two cycle mix to provide some extra lubrication, all bearings, the
exposed piston skirt was given a drop of two cycle oil and the
grease cups were given a little turn. I opened the volume screw a
little, and turned it over by hand; nothing. I kept opening the
volume screw and the throttle a little and after a dozen attempts
it did fire! Best of all everything stayed together, no bent iron.
Finally I did get the timing, and gas setting set so it was very
easy to start and would run. Before something broke I took it down
to show Scooter. His expression was priceless, this engine was
completely different from his high performance Volkswagen engines,
but you could recognize a lot of VW parts on this low tech engine I
call ‘VBS Engine.’ Its idea was conceived at Vacation Bible
School (VBS), and it is made with Volkswagen (V), Briggs (B) and
scrap (S) parts. It is an interesting, engine to watch run and has
exposed many of my VW friends to the old engine hobby. It has made
me aware of the time and talents required to make engines and I
have more respect for the early engine builders and the people in
today’s gas engine hobby.

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