BBC Crank flange

In my world, this goofy offset flange means it is a cast crank.

Tell me this isn't the case.

I think to Chevy peeps this means it is either externally or internally balanced, right?

Please tell me this is a forged crankshaft.

wsuwrhr said:

In my world, this goofy offset flange means it is a cast crank.

Tell me this isn't the case.

I think to Chevy peeps this means it is either externally or internally balanced, right?

Please tell me this is a forged crankshaft.

Click to expand...

I don't think the flange will indicate either way. The casting number will tell the tale when you crack that thing open.

wsuwrhr said:

In my world, this goofy offset flange means it is a cast crank.

Tell me this isn't the case.

I think to Chevy peeps this means it is either externally or internally balanced, right?

Please tell me this is a forged crankshaft.

Click to expand...

The crank flange tells you nothing about the crankshaft they are all common, steel, cast, internal or external balance. As stated the flange stays common through-out the whole range. simply for flywheel bolt up. There are many ways to identify the crankshaft but rear flange is not one. MLAO Mark

Is it a 454 or 427? all 454's were externally balanced and 427's internal. Check inside of damper for a thick spot for the balance.

Look at the parting line, thin for cast and wider for forged.

Tap it with a hammer if it rings like a bell it is steel if it is more of a thud cast.

rvrrun said:

Look at the parting line, thin for cast and wider for forged.

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this^^^^^^ post up a pic of the parting line on/behind the snout end.

I haven't cracked it open yet. Just checkin on you chevy folk.

I know about the parting line as it is the same process regardless of brand.

I just made a mental note when I took the flywheel off and thought to ask.

Brian

mjc said:

Is it a 454 or 427? all 454's were externally balanced and 427's internal. Check inside of damper for a thick spot for the balance.

Click to expand...

454

Hit the edge of the flange with a grinder...the color of the sparks should tell you what you're dealing with.

lbhsbz said:

Hit the edge of the flange with a grinder...the color of the sparks should tell you what you're dealing with.

Click to expand...

:yikes

I was just looking for a prelim deal. You are an animal.

Brian,

If it was out of the block, just a little tap on a counterweight with a small hammer and you can tell by the resonance of the ring. Cast should hear somewhat a 'thud', steel will be more of a ringing sound.

Good luck!

OR

OLDRAAT said:

Brian,

If it was out of the block, just a little tap on a counterweight with a small hammer and you can tell by the resonance of the ring. Cast should hear somewhat a 'thud', steel will be more of a ringing sound.

Good luck!

OR

Click to expand...

Its all good, when it is out of the block, Ill know by looking at it, it was just an initial, "Shit" moment when I took off the flywheel.

Flange is Mark IV two piece rear main seal. No flange is Gen V and VI one piece rear main seal.

Does not determine forged or cast.

BDMar said:

Flange is Mark IV two piece rear main seal. No flange is Gen V and VI one piece rear main seal.

Does not determine forged or cast.

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Good to know. Sweet.

I guess I am just waiting for the other shoe to drop on this deal.

Is this motor an internal or external balance?

Why did you pull it? Just put some Lucas in it [emoji13]

wsuwrhr said:

In my world, this goofy offset flange means it is a cast crank.

Tell me this isn't the case.

I think to Chevy peeps this means it is either externally or internally balanced, right?

Please tell me this is a forged crankshaft.

Click to expand...

The main question is: was this an OTS engine or was it purpose built. Most "off the shelf" engines (Merc, etc.) had cast cranks. You needed to move into the MC420 version of the Mark IV 454 to get the forged stuff. I think all of the GenV & Gen VI stuff was forged. If I were a betting man I would say it's a cast crank.