Visual Differences Between Cast Iron & Forged Steel Crankshafts

[raz...@hotmail.com]

Hi there,

I have searched high and low for an answer to this question. I
recently have purchased a 1969 375hp 396 engine. A very rare engine!
Now the only problem is telling if it has all the true internal
components inside as I was told it had.

Can anyone tell me if there are any visual differences between
cast iron & forged steel crankshafts that will help me determine what
is inside. If there are not any visual is there a way to tell...any
factors I can look for?

Any help would be greatly appreciated.

Jeff Gerlitz

[t_dra...@lycos.co.uk]

Hi Jeff!
I hope that the following web-page is really helpful to you!

http://www.mustangandfords.com/howto/29178/photo_10.html

[Stan Weiss]

As the article says the difference in the size of the parting is one
way. If the crank is out of the engine and you hit it with a hammer the
cast crank will make a thud and the forged crank will ring like a bell.
Stan

[jim]

Stan Weiss wrote:
>
>
> As the article says the difference in the size of the parting is one
> way. If the crank is out of the engine and you hit it with a hammer the
> cast crank will make a thud and the forged crank will ring like a bell.

No that's not true. There are many different cast iron alloys. Gray iron
will have a dull thud when struck, but crankshafts are typically made
from ductile iron which will ring when struck. Ductile iron (depending
on the alloy) can actually have more of a ring than steel which makes
more of a clang type sound. Cast iron engine blocks OTOH are usually
made of gray iron and will make a dull sound when struck.

-jim

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[Steve W.]

Look at the parting line on the crankshaft. A wide line that isn't in
line over the length of the crank, with grind marks means a forged crank
while a narrow line that runs inline down the crank is a cast crank.
The reason is because the forged crank is forged then the flash is
ground, then it is twisted into it's final shape while still hot, while
a cast crank is cast in shape, cleaned of sand and flash and then
ground. The twisting of a forged crank means that the parting line moves
on each throw.

--
Steve W.

<raz...@hotmail.com> wrote in message
news:1153208860....@m79g2000cwm.googlegroups.com...

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[t_dra...@lycos.co.uk]

Could you explain what exactly is the "parting line"? I am sorry but
often there is a language barrier... Thanks!

[MasterBlaster]

<t_dra...@lycos.co.uk> wrote

> > Look at the parting line on the crankshaft. A wide line that isn't in
> > line over the length of the crank, with grind marks means a forged crank
> > while a narrow line that runs inline down the crank is a cast crank.

> Could you explain what exactly is the "parting line"? I am sorry but

> often there is a language barrier... Thanks!

You want to cast something? You need a mold. Where the halves of the
mold join, there will be a "parting line".

You want to forge it instead? Shoot a straight hunk of steel between two
dies, then pound the crap out of it until it's sort of crankshaft-shaped, then
twist it so the journals end up where they're supposed to be. This tends to
shift and deform the "parting line" created by first pounding all over the place.

Start here (pretty pictures and everything):
http://www.carcraft.com/techarticles/116_0308_crankshafts_how_to/index.html