So following advice from Greasemonkey, we decided to have a look at the misfire on Cylinder 3, and that escalated quickly! The biggest buggerance factor was getting the rocker cover off and then out. A little correctly applied leverage lifted it free, but it took disconnecting a coolant hose to be able to lift the cover out completely.
And out it came. Passed over to the apprentice to clean up and remove all traces of the knackered gasket. And this is the view underneath.
Checked the valve clearances, and they all seemed okay, especially those for Cylinder 3. Scratching head, a mechanic arrived and talked us into removing the head to check for a burnt valve (also as suggested by Greasemonkey).
Cambelt off, a borrowed Torx set and some f-ing and blinding later (one cylinder bolt which did not want to move), the head came off. Gently lowered to the floor.
Turned it around, expecting to see some nibbling on the edge of a valve, but nope, they checked out (no picture unfortunately!). So where’s the misfire coming from? Well looking back at cylinder 3 we noticed a heavy score almost the full visible length of the bore. Could this be it?
So we’re going to look into this and the possibilities. It might be worth upgrading to a 2 litre with another short block, alternatively if we’re to keep what we’ve got, maybe a careful honing with new rings, or an oversize re-bore. We’ll let the experts guide us on this!