Doug:
The AV engines of both water and air cooling types were 80mm bore by 110mm stroke, 33.7cu ins, 553cc capacity.
Note that there were series I and series II engines, series I had horizontally orientated injectors, series II had them at 45 degrees to the horizontal.
I hold manuals for nearly all the Petter diesels and some Armstrong Siddeley (AS1 etc) engines which were taken over by Petters.
There are also the B, PJ, PC, PH, PHW, AC, PDV, AA, AB, PA, PAZ, BA, and a few variants on the themes.
I took some pic's up the farm last weekend of the AVB and AV1 engines, I'll get them on our website over the weekend.
The Cub diesel (flat twin water cooled) contributed some of its bits to the AV1 series I engines, but that was not a success with poor starting from cold, so the AV Series II was developed with the angled injector and revised injection details. The Cub's are another fascinating little power unit in their own right, there are some details and pictures on the website.
Peter