To complete the base I swapped the flycutter for a boring head and machined the socket for the liner. The tool shown in the boring head is one I use to put a final chamfer on the corners.

I then put a rough hole through the cam side bearing before returning to the lathe once again to mount the casting on the cross slide but this time the machining plate was clocked at right angles to the lathe axis and a wobbler used to pick up the location for the hole.
The other bearing housing was then drilled out so a between centres boring bar could be used to open out both housings to finished size.
With the lathe work done it was over to the mill to machine the timing gear stud hole and faces for the push rod brackets
The next part to be attacked is the cylinder, I spent a while working out where best to place the cuts and put some basic marks onto the casting. The bosses for the rod guide and ignitor can't really be moved so the end faces were marked from the bosses.
The face where the hopper mounts was the best face to use for the initial holding but was not totally parallel to the cylindrical part so a feeler gauge was used between the casting and the angle plate and a cleaning up cut taken over the head end.
This freshly machined end was then placed against the angle plate and the top face cleaned up but left oversize at this stage.
I then knocked in a temporary plug and marked the centre to make it a bit easier to set things up in the lathe, the machined end of the cylinder was set back against the chuck to keep things square and the end faced.
I then mounted the old 4-way toolpost that came with the lathe and centred up a 16mm indexable boring bar and used that to open out the bore. Its not easy to see but the bore does not go all the way through as the end of the liner needs to butt up against the face you can just see in the bottom of the hole. The inner diameter is also 0.010" smaller than the outer so the liner can slip most of the way in before the press fit takes hold.
The casting was then re-chucked so the other end could have the cored hole cleaned out to 0.100" undersize and machined to final overall length
 
GALLOWAY 5HP HIT & MISS BUILD IN 1:3 SCALE
By Jason Ballamy 
Part three - base and cylinder
M4. C4n