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My webster build

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dbvandy:
2 months ago I could hardly spell "lathe" but I wanted a new hobby, so I found a lightly used, but broken 7x12 on craigslist for $200 with some tooling, bought a replacement board from LMS, and started making swarf.  The internet is a great place to find ideas and how to's so I started searching.  I came across Joe Websters free 4 stroke plans: http://home.comcast.net/~webster_engines/... and I was off.

I first made a bolt... and was pretty proud of it, then a little wobbler, it worked well, but I wanted something that made fumes....  so I started on the Webster.  Luckily there is a Metal Supermarket 4 miles from my house so I purchased the raw stock needed for the Webster and started turning.

The cylinder and piston were first, then the head.  It was fun over Christmas to show my friends and family what I had created.  Everyday I made another piece and I got a little closer to "first pop". It happened on January 9th, after 8 build days in the shop.

All the parts shown with the exception of the bearings, plug, bolts, ignition coil, and finned flywheel were made from scratch, some based on the basic plans.  I did not want to go the points and condenser route because of the luggage you have to haul around in order to run the motor.  I had found a dead weedeater on the side of the road 2 years ago and I tossed it in the "to be used someday" pile.  I works VERY well and I plan to use this type of ignition in the future because it is so reliable and cheap.

The vapor carb is based on Jan Ridders idea, but completely designed and built by myself.  I used a carb off my old RC10 GT nitro car and it worked ok, but was a pain to adjust and not reliable, so I use the vapor card exclusively now.  I can adjust the mixture with a turn of a long nut that covers and uncovers a hole on the intake tube.

I am currently running straight Coleman fuel with a few drops of marvel mystery oil, but have used nitro methane, denatured alcohol, 87 oct gas, butane, propane, rubbing alcohol, and mapp gas (stinks...).  the coleman fuel can be run in the house for short times and it has a pleasant odor like I am camping...

The ignition timing can be adjusted by moving the coil up and down thus changing the spark from 20 degrees BTDC to 20 degrees ATDC.  A neat effect of this is that you can adjust the idle from 1000 RPM to 4000 RPM just by changing the timing.

It will start with a swift turn of the flywheel, but this gets old quick so I installed a one way bearing and nut from an old RC rope starter and I can use my drill with a 12mm socket to start it.  It just takes 1 or 2 revolutions to fire and then revs to full RPM.

I might add a rope starter pulley and a PTO pulley some day, but for now I am done with modifications and am starting on Jan Ridders OTTO engine.

This is a pictorial of the finished parts....

dbvandy:
here are some pics of the completed parts.

dbvandy:
More Webster parts....

dbvandy:
More Webster parts...

dbvandy:
Some Webster videos...

first pop: January 9th, 2011.  I was afraid to adjust it for a few hours....


A close up of the valve train without the flywheel installed.  The gears were made from aluminum bar stock modeled after the 20 and 40 tooth gears from my 7x12 mini lathe.  I made an arbor and mounted the blank to the plastic gears and then cut the tooth profiles with a dremel grinder.  Turned out pretty good, I think.  The cam was made from a 1/2 inch bolt that I turned down to the high OD of the cam and then carefully sanded away the small OD with my 36x4 inch belt sander.  I had to adjust the duration after it was mounted on the gear, so I used a file and a sanding disk to knock it down.


the finished motor running. normal running speed is about 3000 RPM and can be changed with the ignition timing and fuel mixture.  The mixture from the vapor carb is adjusted by turning a piece of threaded tubing that covers a slot in the intake tube, thus adding air to the 14 to 1 fuel vapor in the tank.


The motor idles about 1000 RPM because the ignition system needs that to generate a spark and will go up to 4000 RPM just by adjusting the timing from 20 DEG ATDC to 20 DEG BTDC.  The Vitron o-ring gets a little sticky at high heat from high RPM's, so I have to squirt a little WD40 in the cylinder to lube it back up.  With low RPM's the oil in the fuel does fine keeping it cool and lubed.  I might install an oiler someday, but it is very easy to just spray a light oil squirt every few minutes...

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