By Jason Ballamy 
Part nine - Rocker and governor arms
M4. C4n

The rocker arm post fits over the intake valve and is supplied as a bronze casting. First job was to get it running true in the 4-jaw and face the end followed buy boring out the hole for the valve and spring to fit inside.

A mandrel was knocked up to fit the bore, the end faced and centre drilled to give additional support while the outside was turned.
Then over to the mill and into the rotary table to drill the three mounting holes, without turning the table it was reset from vertical to horizontal and the slot to get access to the valve milled.
It was then mounted onto a block of aluminium so it could be easily held and indexed while the end was milled to shape.
I had to use a long reach mill to cut the slot for the rocker arm.
A rough and ready jack was used to help support the end while the pivot pin hole was drilled & reamed.
The part was finished with some hand filing of the end and around the three bolt holes.

The rocker arm is a fairly straightforward steel fabrication. Start by marking out and drilling/milling the holes in a bit of plate. Then saw and file to shape, add a bit of rod with a locating slot.

Silver solder the two together and machine the pad back to size.
And basically done and fettled to make it look more like a casting.
The governor arm is a similar steel fabrication but a bit more involved as it has a forked end. Again I started by marking out and then milling the holes in some plate before cutting and finishing to the lines.
The fork was worked onto the end of some 3/8" flat stock, starting by boring a hole to form the inside curve of the fork.
Followed by a bit of milling to form the two fork prongs.
Quick slot to locate it on the end of the other bit.
Mount on the rotary table with a bit of packing between and round the outside of the fork.
Drill and tap for the pins that fit in the governor spool.
Solder together with the addition of another pad set into a hole. By leaving the fork on the parent bar it was easy to make sure the two parts were in line.
Job done!