Those ammeters CZ27 seem to be rare as rocking horse poop.
Is there any experience replacing the 1 5/8" with a new Lucas one that measures 1 3/4" ?
Or use the interior of a new one in an old casing...

I think there is some confusion over the sizes..It depends whether you measure them over the body or over the rim...

Modern replica ammeters (1 3/4") fit the Lucas switch plate used on the M20...

It's similarly confusing when discussing headlamps I find..The same lamp can vary from 5 3/4" to 6 1/2" depending on where it's measured.. ..Ian

email (option): ian@wright52.plus.com

Thanks Ian, it's clear now
Hans