rocco wrote: ↑Mon Sep 12, 2022 1:08 pm
"During the 60s when I worked for HA Saunders we received gold seal engines every week and many were oversize pistons, mainly 30 thou which is now not made by piston manufacturers. I had an 8G9 engine in my Austin A35 with FA stamped, F for 30 oversize pistons and A for the std crank. --- We would always look for Mini engines especially Coopers with larger bores and std cranks for competition use. Anything up to H was plus 40 was fitted. From my notes at work see below.
On Gold seal engines there is a stamped in code (not the raised code) on the engine number plate, both letters tell you, the first letter is the bore size and the second letter is for the crank size. for example my 1957 A35 with 8G9 engine was FA which (F) meant 30 thou oversize block and (A) was standard crankshaft. (M) rarely ever being used".
A = STD
B = 10thou
D = 20thou
F = 30thou
H = 40thou
M = 60thou
My car has a tag with some raised letters and numbers and with "A D" indented/punched underneath. Meaning it has a standard crankshaft and a cylinder bored out by 20thou. Or is it the other way around as described in the "FA" example above?
That's a fairly recent addition to the mgaguru website. I've seen other places, as I mentioned previously, where the additional 2 letters, i.e. the 'AD' was alleged to be the engineers initials...
Most examples I've seen have been AD, including my own car's engine, so I'd go with the interpretation of Block and Crank in that order, so A = Standard Block and D = 20thou oversize Crank.
But to be quite honest, does it really matter?
Does it affect the price of fish, to paraphrase an old saying?
It's only relevant to any future Refurbishments, when new measurements will be taken anyway. So it's only of curiosity value.
So long as you know what engine you have, that's really all that matters.
