Oddly enough, one of my learned BSA gurus maintains that an A7 will not run properly on a 357 cam, and he knows a lot more about BSA twins than I ever will, despite my 45 years experience of them. He was a bit taken aback when I told him that my A7 has been running a 357 cam for the last 40 years very happily. He still thinks it would be better with a 356. Anyone out there have any opinions?