Machining the Main Casting


Facing off the bottom of the casting  Live action  shot here

Machining the pocket for the fuel tank bottom plate.


A dovetail cutter was used to machine a groove to help retain the plate when it is epoxied into place.


Two dowel pins were added to help with locating on the fixture plate that will be made.

Mounted to the base casting.  A nice big piece of iron!

Mounted on the fixture plate

Boring the cylinder came next:

With the fixture in the vertical position I used a 2" boring head on a 3/4" stub adapter and a 6" boring bar shortened to 5 3/4 inches.  With the knee all the way down the cutter would sit about 3/16" above the face and it would just come through the other end of the bore (just barely).   I had enough clearance that I could remove the boring head as an assembly from the machine without disturbing anything.



Mounting the main bearing caps:

Drilling and tapping the main cap stud holes.  I used flexible super glue to mount the caps to hold them in position while doing this.  Funny thing was, it took a pretty good whack with a bronze hammer to break then free!


Fuel Filler Tube & Cap:

After facing the casting at the spot where the fuel filler tube will be located I drilled and then tapped a 1/16 npt hole.

A piece of heavy wall brass tubing from the scrap drawer provided a 1/16 pipe nipple after some threading using the collet chuck and Neil Butterfields really cool tailstock tapping tool.  A cap was turned from a piece of bronze rod and knurled for looks.

Drip Lubricator Installation:

The relief for the lubricator pipe was cut with a 3/8" end mill


Due to the deep pocket of the water jacket I had to make a tap extension to reach where I need to thread.  Piece of 3/8" stainless rod and a 4-40 Allen set screw did the job.  T handle by Irwin did the trick.


Installed drip oiler and fuel filler tube.  Later on I shortened the pipe so the top of the union just barely stuck up above the casting surface.


Spark Plug:

Drilling the plug hole, side holes and the pocket.


Setup to tap the 10mm x 1.0 sparkplug hole.  Not being familiar with cast iron I elected to hand tap and used an angle plate to hold the fixture .


Crankshaft Bearings:

The casting and jig was flipped and the centerline of the cylinder bore was checked to verify the alignment with the mill table.  The pads were faced off, but not to spec at this time.  The bushing journals were drilled to just under 0.625 and then reamed to .001 oversize for a tight fit when bolted together.  After bolting it up, the bores of the bushings were reamed to 0.500" and piece of drill rod was used to check the fit.  Nice smooth fit!


At this point I could not resist hanging some of the goodies on the casting.  The shortened drip oiler pipe is not shown in this shot.