Is this a cast or forged crank?

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65 Cuda 340 said:
OK, I'm gonna stick my neck out and still say the bottom one is cast. Note that the center counterweight is significantly smaller. Also, the rod bearing widths are narrower. I'm not aware of any slant six forged cranks with a smaller center counterweight or smaller rod bearing widths (of course, I have been wrong before). Here's a pic that Dutra posted on Slant Six Org. a few years ago, when he was putting together an aluminum block slant six with a cast crank. Looks to me like the bottom crank above, albeit ground on (lightened) a bit:

View attachment 1715738517

Another:
View attachment 1715738518
Click to expand...

It's forged. I see what you're saying, but it's been lightened up. Look at the edges. See how rounded they are? Dead giveaway it's forged.
 
65 Cuda 340 said:
OK, I'm gonna stick my neck out and still say the bottom one is cast. Note that the center counterweight is significantly smaller. Also, the rod bearing widths are narrower. I'm not aware of any slant six forged cranks with a smaller center counterweight or smaller rod bearing widths (of course, I have been wrong before). Here's a pic that Dutra posted on Slant Six Org. a few years ago, when he was putting together an aluminum block slant six with a cast crank. Looks to me like the bottom crank above, albeit ground on (lightened) a bit:

View attachment 1715738517

Another:
View attachment 1715738518
Click to expand...

But hang on now......you might be right. The rod journals kinda give it away now that I look again. I think you're right.....but somebody purdyed up a cast crank, didn't they? It looks good.

I'm actually kinda lookin for a cast crank slant six.
 
RustyRatRod said:
But hang on now......you might be right. The rod journals kinda give it away now that I look again. I think you're right.....but somebody purdyed up a cast crank, didn't they? It looks good.

I'm actually kinda lookin for a cast crank slant six.
Click to expand...

So my neck survives to another day? <g>
 
I've seen 340 and 440 cast cranks and their forged counterparts. Easy to tell the difference - the more clearly defined, sharp edges, the much narrower parting lines, etc. But other than maybe the narrower center counterweight or the narrower rod bearings, I don't believe I would be able to spot the slant six cast crank as being a casting. Unless there's something visible in the flesh that doesn't show in the photos. As I said, I've never held a slant six cast crank, just maybe seen pix. Anyway, here's another illustration I pulled off the web:

1977-crank.jpg
 
65 Cuda 340 said:
Found this pic on line. I believe top is forged, bottom cast. If that is so (and I've never had a cast slant six crank physically in my hands), they do look different, but not in the way cast vs. forged V8 cranks do. Please correct me if the bottom pic is not a cast slant six crank. The pic came from a Hot Rod article on building a hot slant six, and the cast crank was chosen because it was strong enough and a lot lighter.

Chrysler Slant Six Cylinder Engine - Mopar Muscle Magazine

View attachment 1715738436
Click to expand...
Looks like the bottom is cast.......just look at the bearing widths...definately smaller and indicative of the cast crank.....
 
easiest/best way is to measure the journal rod width.
FYI unlike many other engines, where cast and forged cranks can be swapped in the same block, not so with the slant six.
The blocks are different, and cranks can't be interchanged.
 
Ok, I'll stick my neck out and say from memory that a forged crank weighs 66 lbs. And a cast crank, from memory again, weighs 14 lbs less.
Just throw It on a scale.
 
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