Actually the Y in 1acr is not strictly pronounced as long E according to Chambers; I thought that too. I am beginning to think it is actually consistent. My objection to 22d is resolved in later editions of Chambers. 42acr still bothers me.
I think one would only change the first letter of 47acr to J if the word started with the sound 'jay'. Doesn't the sound nave to match the name of the letter?