Transitional Engine Cams

I’m struggling with the cam design on this transitional engine. My original thought was around machining this camshaft block that bolts down to the I-beam and two cams hang over the side of the engine to drive both inlet and exhaust.

Now I’m having a re-think that this should really use eccentric cams like a traditional steam engine – the timing won’t be perfect, but it will be interesting and it will run, maybe it won’t be the best running engine but it will run.

There isn’t much room to fit the larger gear as the crankshaft web is quite thick, I need to thin down the bearing block so that the gear can then run central on the smaller drive gear.

The first job was to cut the bearing block down and remove the proposed outer support.

I then machined a phosphor bronze bearing with a 6mm reamed hole to accept the camshaft.

The block, gear and shaft can be seen in this image.

I next need to machine the eccentrics.

At this point the bearing block is just pushed into place, but this all now looks very sensible. The missing bits are the cams….so how about an eccentric to drive the exhaust valve.

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