Morris Minor Owners Club

My Minor 1000 recently started to make a knocking noise on acceleration and is now running on only two cylinders. I have owned the car since 1978 and was convinced this was an internal failure.
I swapped the spark plugs around to eliminate these as the problem. I removed the rocker cover, turned her over with the starting handle and all valves appeared the be operating as normal. I then removed the cylinder head and the valves looked fine and have since pulled the engine out and inspected the crank shaft. Everything looks intact.
Unfortunately I didn’t notice whether or not the oil light was on when this problem presented itself.
I recently adjusted the valve clearances per the book in preparation for a trip to France and now wondering if I have got this wrong somehow but she drove smoothly on a 2 hour drive just prior to the problem appearing.
Does anyone have any ideas of what the problem might be?

Was the headgasket ok then?

The "knocking" combined with only firing on two cylinders sounds exactly like the symptoms of a head gasket blown between two cylinders to me

Agreed. As you have already got the head off, look at the gasket that you removed and check both block and head with a straight edge. There's another thread running on exactly this type of fault, and I've got one Minor off the road with the same problem.

If the head was removed, I would have thought that a blown gasket would be immediately obvious...............its hard to miss

its a shame you didnt post pror to head off and crank examination,since I.m sure you would have been advised to have a compression test,obviously not possible now untill all is back together. Its the classic symptoms of head gasket failure,and a test would have removed any doubt.

All. Thanks for all your input, which of course was spot on and has left me feeling very foolish for not having checked the head gasket as soon as I had lifted it. The knocking noise had me thinking bearings or valve stem before I realised that two cylinders were out. I least everything else I’ve checked is it good condition although I did find a crack in the exhaust manifold which I will now replace. Thanks again.