[Crumpp]

SPitfire I and Hurricane's which according to your theory didn't use 100 Octane

Glider,

Where in the world do you think I am claiming that Spitfire Mk I and eventually Hurricanes not use 100 Octane? They did not have 16 squadrons worth of Spitfire Mk II's by September.

It is in the Operating Notes that they were capable if equipped.

Crumpp says:
The statement "all Fighter Command was using 100 Octane July 1940" is not backed up by the facts.

The statement "100 Octane was used during the Battle of Britain" is correct and backed up by the facts.

It is clear that Fighter Command was in process of adopting the fuel but it is equally clear that process was not complete in July 1940. There is no agreement on the end dates for the Battle of Britain. So, depending on the dates one chooses for the battle to end, the process was or was not completed during the battle itself.

Crumpp says:
Production priority would go to the newer designs and older ones would be upgraded over time on a schedule that the manufacturer could meet. We do see that schedule listed as older models will be upgraded during their service maintenance.

Production resources are not infinite.

The above explains the process, it does not eliminate the Spitfire Mk I from using 100 Octane.

Edit I also note that the paper outlining the changes says that the changes are already incorporated into the servicing.

It says they are being done AS service maintenance. It is not a modification that is done by the squadron maintenance personnel. That is telling you the modification will happen the next time the aircraft goes for Service Inspection.

There are three modifications that add .020 inches to the spigot depth of the cylinder head top joint. The Service level maintenance personnel can choose which method of compliance meets their needs based on the parts on hand.

1. Modification Number Merlin/64 (requires no new piston rings)

2. Modification Number Merlin/77 (requires NEWLY designed piston rings to be installed)

3. Modification Number Merlin/138 - This is the one being done by the factory on NEWER engines.

Crumpp says:
It could also mean the NEWER production engines, ie the Merlin IIX would incorporate the changes in their design.

Refers to Modification Number Merlin/138. The other two modifications ARE NOT being done by Rolls Royce production. They or their subcontractors are only producing the parts to accomplish the modification No. Merlin/64 and Merlin/77 to the aircraft in service as well as the maintence stock required. The work is being done as service level maintenance.