Webster IC with Magneto Ignition

[BlueRock]

Hi, I've been working on my Webster IC build for a couple of years now (started in mid 2012) and it’s been a bit on and off again with other projects vying for my attention. I'm now pushing forward with the build, time permitting. This is my first engine build and I started a thread over on HMEM but I’m not keen with the direction that site has gone over the last few years so to recap, this is how I got to where I am at with the build.

My build is a little different as I'm using bearings rather than bushes for the big end and the mains. I'm also using a magneto ignition system off an old line trimmer that I bought from a recycling centre for $5.

To lap in the cylinder bore, I made a lap from brass and it can be expanded by tightening up two grub screws that force open the the slit that runs along the length of the lap. I used diamond paste with the lap that I rotated slowly in the drill press, while moving the cylinder up and down, using progressively finer paste with the lap until I had a pretty smooth finish inside the bore.

The crank is silver soldered together. Until this build, I'd always used 2-5% silver solder when soldering up larger mechanical parts or copper pipe. However, I soon found that this percentage solder appears to not be suitable for finer work as it does not flow as readily as 45% that I ended up getting hold of to do the crank. I left about 0.10mm (0.004") clearance between the parts of the crankshaft for the solder to flow into the joint.

[PJW]

Hi, I have just finished building the Webster, It was only my second build & I had some good tips from the members on this forum. I will follow your build with great interest, it is amazing the amount of differences the Webster builders come up with, I like the ignition system, I used the old fashioned points & coil, the condenser was a bit of a problem as car spares shops no longer stock them (shows my age). Your build is looking good & you have done the hard bit, lapping the cylinder, its all down hill from now!

Peter

[BlueRock]

Peter, I like the look of your Webster, especially the black cylinder and rocker arm.

With my build, next came the timing gears and exhaust cam. I cut the timing gears using a hob cutter that I made from silver steel (drill rod). I found this webpage http://www.metallmodellbau.de/GEAR-CUTTING.php really useful for an explanation of how to make a hob cutter (in German but Goggle translator works OK) and also this page http://www.helicron.net/workshop/gearcutting/involute/. The book Gears and Gear Cutting by Ivan Law is pretty good too.

Before I made the gears, I tested out the hob cutter and made a wide 20 tooth gear and cut it in half, making two 20T gears, to check whether the gears would mesh OK. That test worked out so I went ahead and cut the final gears, a 20T module 1.00 for the crankshaft and a 40T for the cam gear. I set up the blanks in spindles held in a drill chuck and machined down the blanks to 22mm (crank) and 42mm (cam). I then transferred the drill chuck, without moving the blanks, to the rotary table set up on the mill.

The gear cutting went smoothly, albeit a bit tedious, with all those teeth and keeping my wits about me to make sure I was advancing the gear to correct amount each time.

Cutting the exhaust cam was a similar process using the rotary table and I hardened it before pressing onto the valve gear.

[BlueRock]

For the ignition, the coil-carrying bracket pivots about the crankshaft on a bronze bush. This enables the ignition timing to be adjusted. I milled a curved slot in the bracket that locks the coil bracket using a rotary table setup that involved using wood screws to secure the bracket to a plywood disc that was bolted to the RT.

[BlueRock]

Next came the lid for the vapour carby/fuel tank and I trepanned the lid to take an o-ring seal. The S-shaped bracket will have a screw on the long end that will push the lid down to seal it. The bracket has a rounded finish that was achieved by milling chamfers on the edges and a lot of filing and sanding.

[PJW]

Hi, for the black cylinder I could not find the correct paint, but I found some BBQ paint, I did have to bake in on but I was pleased with the results.