Bristol 410 engine sump removal

[Thor]

Just to confirm, the 407s to 410s all had the early engine. When launched it was called the 'A' series engine, but when the later 318 was introduced that was also called 'A', so somewhat confusing. The general term for these engines is 'Polysphere' or even just 'Poly'. I think that the crankshafts are more or less identical to later 318s but all else is different. Camshafts are not interchangeable. The later engines are a bit lighter, but many people have a high regard for the early engine, it makes good power for its size and the period.

407s and 408s have an earlier iron-cased version of the Torque-flite transmission, where 409s and 410s have the aluminium case.

I'm not so sure about this next comment but I think some 407s and possibly 408s had 313 cu.in. engines, earlier types than the 318. They look the same but have slightly smaller bore (?).