James,
Thanks for your reply.
When I watched your video of the completed engine (at 25% speed), it's clear that the valve timing is all wrong. If you concentrate on any one cylinder, you can see that one valve opens each time TDC approaches, a different valve on alternate rotations. In each cylinder, the exhaust valve (i.e. the valve you choose to designate as exhaust) should open just after BDC, and close as TDC approaches. Straight after that, the inlet valve should open, and close as BDC approaches. Then a full rotation with neither valve open.
This pattern should follow the firing order (1-4-2-5-3) around the cylinders.
That's how a real engine works, and if you want to teach someone how they do, it's important that the model works in the same way. With the cam as supplied, this is not possible.
The engineer at Teching is now back from vacation, and I'm awaiting his response.
Jake.