1960s etc UK Ford made their future around millions of engines 3 mb engines 1000cc-1500cc with common bore
thousands of FJunior & F3 & touring car race wins - courtesy of Cosworth etc etc
then switched to 5 mb for commonality with (same bore centres) 1100 - 1600cc
iirc the 1100 (and 1300 ?) was able to use cheaper bearing material and cheaper journal surface quality
the MG shown etc etc had uneven bore spacings - presumably unhelpful to the crankshaft design
https://www.triple-mregister.org/forums ... IC_ID=8138
2 main bearings anybody ?
as the sv Austin 7 (even supercharged) and sv & ohc Morris Minor and ohc MG (even supercharged) had till c.1934
the introduction of valve overlap was under consideration by Austin and Morris in those days
of course only these special competition crankshafts had any counterbalancing
notice the Austin one is 2 piece -to allow it to be installable in the crankcase (roller bearing and minimal)
international class ie 'world' speed records were set this way
the 750 MC book told us to allow for pistons 2 and 3 having greater travel (giving variable compression)
I say (was it tried ?) excess centre counterbalance could aid crankshaft survival - but generate a midstroke vibration
the 'good old' British motorcycle engines were 2 mb (twin cylinder)
one Norton had a common bore size and 250 - 400 cc capacity
apparently the 250 cc version was originally intended to be cheap by having an integral iron head/cylinder casting
the valve seats being accessible for machining from below
could the head, 'cylinder block', and 'crankcase' be cast as one piece ?
with this or an Austinish type of engine ?