[Fot] 1296 small journal crankshaft material and Rockwell #

[don at dcphotos.com]

Just when I think I found the answer…

Unfortunately BLMC compounded this by downgrading the steel used for the crank from EN40B to the far inferior EN16U.

I find this:

Triumph NEVER ever fitted a EN40B crankshaft to their engines.

The Mk3/1500 Spitfire and TR cranks were always made from EN16T.


AND THIS:


The story that different materials were used for the Spitfire crankshaft seems to be something of an urban myth - there is a widespread belief that early Spitfire engines used a crank made from EN40 steel as standard, and later ones used the cheaper, inferior EN16. I don't know where this story originated, but I reckon that someone has confused the Triumph 1300 engine with the BLMC Mini Cooper 'S' 1300 engine, which did use a crank made from EN40, up to around 1968. After that, even the Cooper 'S' used EN16 for the cranks, which were generally tuftrided to improve durability. To the best of my knowledge, all Triumph engines used EN16, it's just that the small crank 1300 engine had a lighter crank and lighter conrods - that's why it doesn't self-destruct like the 1500. If you still believe the Mk3 Spit had an EN40 crank, just remember that exactly same crank (Stanpart 307422) was used in the Herald 13/60 saloon/sedan, and most of the Herald 1200 engines. Those models were produced in larger numbers than the Spitfire, had only a single carb, and were about 10BHP down on the Spit Mk2 and Mk3. Why would Triumph use a better material than absolutely necessary for a low powered saloon car?


Don

DON COUCH PHOTOGRAPHY
(512)-680-3540

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