Oxendine, just take the head off, that way you can carefully go through it and make sure the valves are free, and rebuild it if necessary.
Now you can clearly see what's going on in the bores.

 

Now that is the best idea of the day although we might have learned things along the way that could be useful to others.

You never know. You might find that missing nut in one bore & save bending a conrod or head, valve & piston damage. Bill Mac found a nut in the cam chain drive.

 

This may be a bit of a tangent, but, with all the discussion of Oxendine's engine​​​​​, it's been in the back of my mind that I've not turned over the engine of my car for a long time. It used to move with a tug on the fan or fan belt, but not anymore. I couldn't find my 1 5/16 AF socket, but Amazon has provided a next day replacement. Fortunately, the crankshaft turns nicely, however the water pump is absolutely rigid. Since that's ultimately going to scrap, it's not too worrying. Still it might be indicative of how much gunge there's to be removed from the water passages.

 

You want to get that rotten water pump off & check the state of corrosion of the aluminium chain case behind it unless you are diligent with coolant concentration or the next problem will be water/coolant in the engine oil.

 

I always used a 50-50 mix. However, I drained all the coolant before the car went into storage in 1994. It will be an interesting journey when I eventually get into that engine.

 

Draining the coolant as a storage practice is not a good idea, there are always puddles left in the system that start to corrode and rust things now that air is introduced.

Flush, and install a 5 year coolant in for storage purposes, replace as necessary.
I stored mine dry once _ it's not dry _ what a mess !
One can not get all the coolant out unless they start disassembling everything.

 

All too true, but, I'd taken the radiator out when suddenly I had a lot of things happening at once culminating in moving to the United States. Sometimes life even gets in the way of taking care of old Jaguars.