L34 FORGED CRANK ?

[cars1234]

I bought a basket case L34 motor and i don't know if its the original crank JM book says its supposed to have a Forged steel crank
from what i can find on the google is cast has small cast lines and forged big from being forged,
Also is it cheaper to buy a new crank or have this one polished?
gonna try to post a pic,Any help appreciated.
THANKS

[cook_dw]

Buy some evaporust and soak that crank.  Then take it to machine shop to have it balanced/checked.  Also its a forged crank.  Look for 6223 cast into one of the throws.


https://www.yenko.net/forum/showthread.php?t=136669&highlight=rusted+crankshaft

[cars1234]

Darrell ,thank you....
I will get on it tomorrow first thing..much appreciated!!!!

[Mike S]

If the pits aren't too deep into the surface, a machinist can cut the journals down to clean them up.

Mike

[ko-lek-tor]

Darrell ,thank you....
I will get on it tomorrow first thing..much appreciated!!!!

After you have cleaned it per Darrell’s recommendation, if you want to save a couple $$$, borrow a 2-3” micrometer and determine if that crank has been turned previously. It looks like it has to me? If there is a machine shop you are taking it to, unless it is a very large shop that does all types of machining, chances are it will “farm out” the work to a specialist crank grinder. Not as many of these grinders around these days, so there may only be one place that does this type work in a given area, even in a metropolitan area. Avoid the middle man and find that place and take the crank directly there yourself. But before you do that, have the Mach. shop magnuflux for cracks. Be careful, you can easily have a few hundred sunk fast in this crank. Sometimes an exchange crank can be made called a “crank kit”which includes bearings. Avoid cranks sent out of the country to be turned if you go this route. If you end up having your crank turned, make sure bearings are available for the new size journals. Use common sense and you can evaluate the needs of any machined part for yourself. Another overlooked clearance is the thrust flange.

[cook_dw]

Bentley and Mike make valid points..  My comments were assuming the crank was known good and was in hopes of removing the rust by turning.  Either way, if it were me I would probably still do the Evapo treatment.  Regardless what the outcome is of the crank as long as you crank was free of grease and oil before submerging it then the Evapo can be reused.  I would strain it before putting it back into its container though. 

[Kelley W King]

I think I would hit it with the good old wire brush first so the loose stuff does not slow down the evaporust treatment.

[cars1234]

Anyone know the original specs if i MIC it to see if its been turned?

[cars1234]

Anyone know the original specs of the crank if i mic. it?
the motor also came with a set of pistons i'm guessing bored .40 over ?
top of piston stamped
402P  .40
09407-05-B

[ko-lek-tor]

http://www.mortec.com/journal.htm

scroll down to bbc


pistons appear to be .040 402 pistons? that bore would have to be around  4.165in., if that is the case?
What are the numbers on the back driver side of block?  Generally a seven digit number and about 1/2 in. tall font is what you are looking for.

[firstgenaddict]

The wide parting line is the tell tale mark... however Forged cranks ring when tapped as well...

[bcmiller]

Rounded off numbers for journal sizes are
2.200” on the rods (but are usually 0.001 under) - so about 2.199
2.750” in the mains (but are usually 0.001 to 0.002 under) - so about 2.748 to 2.749

What year is the 402 block and what is stamped on the front pad of the block? 

[cars1234]

The block is a 3955272 the pad is stamped T0728CJI vin# stamped by the oil filter 19N693255 weird some sites say 396 others say its a 402

[bcmiller]

It’s an early 402 from a late 69 Camaro.

See this link. 
http://www.camaros.org/drivetrain.shtml#PadStamps

Can you post a pic of the pad or send me a pic via pm?

[bcmiller]

I will check to see if we know anything about the car it was supposed to be in originally.

Edit: I don’t see anything on that VIN.