Are crankshafts normally hardened ?

[Jens]

This is a question falling under the heading of 'idle curiosity'.  I pulled the gib keys on Thumper today and noticed some scoring on the crankshaft. It was surprisingly easy to remove. Surprising because I would have expected a crankshaft to be either hardened or to be something like 4140 steel. Instead, this thing seems to be as soft as butter.
Anyhow, work on Thumper is slowly proceeding again although a stuck flywheel (now sitting with penetrating oil) has halted things. I am hoping to get the crankshaft out and to the machine shop this week.

[spencer1885]

Idian crankshalfs are made from EN9 steel if my memory is correct where as lister used EN16 I think or some thing like that.
So much softer and that's the sort of difference between a copy and a original.

[Tom Reed]

The crank journals on the 345 engine in my '74 Scout II are advertised as induction hardened. The crank is forged steel to, not cast iron.

[mobile_bob]

crankshafts come in all sorts of flavors

there are plain cast iron cranks, useful for inexpensive gasoline engines of reasonable output, such as a family car

there are cranks cast of nodular iron, good for higher output engine's

there are cast steel cranks, for even more output

there are those that are induction hardened, and those that have "rolled" fillets

there are forged steel cranks, and

there are billet steel cranks, those that are used primarily in extreme output engines like race car/boat/planes etc.

i would suspect that the listeroids use a cast steel that is then forged to shape, likely without any form of hardening or tempering
and machined with adequate attention to the radius of the fillets to allow for a strong enough crank for the relatively low output of
the engines they are used in.

with the very low incidence of crank failures in listeroids, it is unlikely that there is a need for anything better than what they are producing
and delivering.

as long as they don't start putting out plain cast iron cranks, i think they will remain safe to use.

bob g

[AdeV]

If it's a concern to you, investigate having your crank "nitrided". This is a case hardening system often used on race car engines to beef up a stock crank. It would certainly make your Listeroid crank hard enough to last pretty much forever.