VBS ENGINE

VBS Engine

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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 24x14 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 2x4 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.