Dura Cast or Steel cranks

the-big-e

Registered User
Is there any way of telling a steel crank from a dura cast crank.....:confused:

The cranks are out of the engines and the bodies are gone.....
 
From my experience with other engines, cast cranks have a relatively wide parting line, and forged cranks have a narrow, more well-defined parting line. I'm not sure this is applicable to these crankshafts or not, though.

JD
 
From my experience with other engines, cast cranks have a relatively wide parting line, and forged cranks have a narrow, more well-defined parting line. I'm not sure this is applicable to these crankshafts or not, though.

JD

What do you mean by parting line?Do you have any pics?
 
Are they cranks from an '89 SC? The easy way to tell is if there is an R in the VIN code. I forget the arrangement of the letter is in though.
 
See if this applies...no idea if it does vis-a-vi the SC

There are two ways to tell the difference between the two crankshafts by looking at them from the back (transmission end).
  • The forged crankshaft has a circumference profile that is a perfect circle just outside of the bolt circle. The cast crankshaft, on the other hand, has a hump or raised area that extends outward from the rest of the circumference.

  • The second visual difference is the bolt circle itself. The forged crankshaft has an evenly spaced bolt circle. Since there are no added weights to either the torque converter or the flex plate on an engine with a forged crankshaft, the flex plate can be bolted to the crankshaft in any position. On the cast crankshaft, one bolt hole on the bolt circle is off-set so that the flex plate can be bolted on in only one position.

Ken
 
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See if this applies...

[*]The second visual difference is the bolt circle itself. The forged crankshaft has an evenly spaced bolt circle. Since there are no added weights to either the torque converter or the flex plate on an engine with a forged crankshaft, the flex plate can be bolted to the crankshaft in any position. On the cast crankshaft, one bolt hole on the bolt circle is off-set so that the flex plate can be bolted on in only one position.
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All SC cranks are zero balanced. I believe the note above is specific to a non-sc cast crank. A Cast SC crank is nothing like a NA cast crank. Ford was attempting to use a new casting process that resulted in a part nearly as strong as a forged part. Actual results had them just not working out.

A parting line is where the two haves of a mold join or die join when forming the part. It will be a line that runs down the length of the crank, most obvious on the non-polished areas of the crank.

Cast parts have a very thin parting line. This is because the mold forms are bound tightly together to prevent the liquid metal from running out.

Forged parts have a wider parting line, this due to the metal squishing out as it is displaced by the dies as the part is forged through heat and pressure. There are often obvious grind marks on a forged parting line as the excess metal is ground off.
 
Mike8675309>There are often obvious grind marks on a forged parting line as the excess metal is ground off.

Any idea if SC cranks were twist or non-twist die pressed?

& FWIW examples:

"When looking at a cast (left) and forged (right) crank next to each other, it's obvious why the forging process fetches a higher price tag. The cast crank's rough surface shows very little finishing machine work is required, as the casting process yields a shape that closely resembles the end product. The forged crank's smoother appearance reflects more extensive machining operations required after it leaves the forging die."

0710phr_06_z+crankshaft_tech+.jpg

...and the lower end of an SC motor...
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Mike8675309>There are often obvious grind marks on a forged parting line as the excess metal is ground off.

Any idea if SC cranks were twist or non-twist die pressed?

No, I'm not sure. I would assume it was through a process common to Ford and other manufacturers for forging cranks at that point in time. I've seen articles including this one http://www.sccoa.com/forums/showthread.php?t=31614&highlight=duracast+ford+engineer that show how Ford had every original intention of using this new "duracast" process. That would lead me to believe the Forging process used was likely whatever current process was available to them.

I have found conflicting info on the duracast cranks as locating any in the wild is difficult. Thus I find it may be possible that a duracast crank may have a weighted flywheel and or flexplate to achieve final balance.
 
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