Cast Iron Crankshaft?

[fltenwheeler]

Hi All

One of the Hit & Miss engine manufacturers has an option for a cast iron crankshaft at a cost of $15.00.

How well do they work?

Thanks

Tim

 

[gbritnell]

Hi Tim,
Over the years there have been hundreds of thousands of automotive engines with cast iron cranks. I would say if the casting is from a good quality iron it should pose no problems whatsoever.
gbritnell

 

[compspecial]

Hi, I think cast iron crankshafts became popular after the introduction of 5main shafts for four cylinders and 7 mains for sixes i.e. supported each side of every throw.
strangely, when I worked on "holden" engines there was sometimes a tag reading "not for export-forged shaft" can anyone explain this?

 

[bentprop]

Presumably,a forged steel shaft was cheaper to make than a cast iron one.
I don't see any other rational explanation.
I do like cast iron,even though it makes a godawful mess of your machinery.
The only problem with a casting is,you cannot make a mistake.If you do,the part is usually history :-\

 

[Jasonb]

You need to check what grade CI it is. A grey CI crank will be too prone to fracture, what you need is SG Iron(Spheroidal Graphite) this has a different carbon structure and makes a much more suitable crankshaft. It machines more like steel and I find some form of cutting lub helps, Oh and it smells when machined.

Forged steel was used in the past as the CI they were able to produce was prone to fracture not because it was cheaper to make

This is the Crank on my 2" tractionengine which is SG iron as is the front axle

Its usually advisable to rough turn the crank leaving all surfaces oversize and then leave the casting to settle for a few weeks to allow any stresses to come out. Looking at the one on your pic I would machine it all over including cutting out teh stiffening rods and then let it sit for a couple of weeks.

Jason