Cylinder Extensions

The stroke on this engine is four inches. I needed a little more length on the castings I’m using. I made four cast iron rings about 0.525 inches thick – one for each end of each cylinder.

I mounted the casting in a four jaw chuck to face the ends and take a short rough cut on the bore.

The rings were sliced from a bar of cast iron. The first step was facing each side to length (thickness).

I drilled the disks to one inch inside diameter.

The I.D. was bored to the same rough diameter I had bored the cylinders.

I drilled an eight hole bolt circle in each ring. I then match drilled the bolt circle to the cylinder ends. In the photo above, I am drilling two opposite holes into the end of the cylinder.

I tapped the two holes to no. 8-32.

I drilled a clearance hole and counter-bore on the two holes in the ring that correspond to the two tapped holes in the cylinder.

With the ring screwed to the cylinder, I match drilled the rest of the holes. Note the witness marks in the ring and the cylinder for aligning each ring to its corresponding cylinder end.

The bolt circle has now been transferred to the cylinder. The rest of the holes were tapped in the cylinders and the holes in the rings were opened up and counter-bored.

After lapping the rings and cylinder ends, one face was smeared with Loctite No. 510 Flange Sealant. The 8-32 socket head cap screws were installed with Loctite No. 263 thread sealant.

It may be overkill, but I filled the screw heads with epoxy to discourage anyone from ever removing these extensions. They will be bored and drilled with the cylinders as if they were one piece.