Folks,
I believe that, if you go further back into the history of the Griffin and, later, the Merlin, you will find in RAF specs. the notion that the Griffin would be too powerful for a fighter (??? I know, but I am only the messenger) as a "36 litre class engine", therefor a "24 litre class engine" should be developed, which became the Merlin.
As many of you will know, there were serious problems with the early Merlin development, up to and including into Squadron service. It is reasonable to say that many of the production standards problem with the Merlin were only (partly) solved when they were "productionized" by Ford of UK, and Packard later introduced further improvements.
As references, see "Not Much Of an Engineer", Sir Stanley Hooker, and the autobiography of Wing Commander Rod Banks, the fuel expert, and inter-war representative of International Octel.