The Steamboating Forum

I have a problem with my engine that I need some help or information for. The engine is a single cylinder David King (of Norfolk, UK) 2 1/4" bore, 2 1/2" stroke. I am pretty sure the piston rings are cracked or seized (or worse) but I cannot find out how to open up the cylinder. There is no obvious cylinder head, just what appears to be a one piece casting for both the main cylinder and the piston valve cylinder. At the top of the cylinder is a 1" domed steel cap tapped 3/8" with a bolt which when removed allows me to see the top of the piston and the retaining nut on the piston rod. Under the dome is a g cast brass disc with the makers name which can be rotated relatively easy so I assume is retained by the dome. Reasonable force with a 14" wrench has not moved the dome!
At the bottom of the cylinder block is a lightly knurled collar into which the piston rod gland screws. The cross head guide tube is incorporated in a pillar casting that supports the cylinder block. Due to the arrangement of the pillar casting it is virtually impossible to gain any purchase on the collar to try and unscrew it assuming it is a screw fitting into the bottom of the block. There are no obvious fixings between the cylinder block and pillar castings or any evidence of a separate cylinder head. Photo of top of engine attached. Does anyone have any information on this engine or know how to remove the piston from the cylinder?
Any help or information welcome.

Nigel, I replied on your other thread (Welcome section), not that I think I was able to be too helpful.

Hi Mike.
Thank you for your reply, I have posted to the technical section in case there is a technical wizard out there who does not expect to find technical questions in the welcome section. The main problem I have with the engine is that I cannot see any obvious fixings or assembly joints between the block and pillar castings that would give access to the main cylinder. I was hoping to find out a bit more about how the engine is assembled before applying more force to the parts that look like they should unscrew but may need a bit of persuasion! Simon, the Forum owner has directed me to his dad John Maltby who I will try when I get some clear time.
Nigel.