Picked up this complete 350/TPI to replace the 305/TPI in my 89 T/A. Completed the initial teardown and found the bearings in pretty bad shape.

Took basic measurements of my crank, as pulled from the block. Is it too far gone to worry about?
I used the basic crank specs of a new crank...If they're not correct please correct me.

Crank specs (New)
Main Journals: 2.4500"
Rod Journals: 2.1000"

Mine (Listed from front to back)
Mains: All main journals, excepting the rear, had striations/grooves in the metal.
1. 2.4415" (Bearing worn but intact) (Worn .0085)
2. 2.4480" (Bearing was rough, Tang nearly gone) (Worn .0020)
3. 2.4480" (Bearing worn but intact) (Worn .0020)
4. 2.4460" (Bearing worn but intact) (Worn .0040)
5. 2.4470" (Bearing worn but intact) (Worn .0030)

Rod Journals: All rod journals had grooves, especially #1 and #3
1. 2.0875" (Spun Bearing - Tang gone but fully intact) (Worn .0125")
2. 2.0970" (Bearing worn but intact) (Worn .0030")
3. 2.0975" (Spun Bearing - Tang gone but bearing fully intact) (Worn .0025")
4. 2.0665" (Spun Bearing - Tang gone but bearing fully intact) (Worn .0335")
5. 2.0910" (Bearing worn but intact) (Worn .0090")
6. 2.0900" (Bearing worn but intact) (Worn .0100")
7. 2.1000" (Bearing worn but intact) (Worn .0000")
8. 2.1000" (Bearing worn but intact) (Worn .0000")

Is the crank to worn to be polished? Reground for oversived bearings? Or should I go for a new crank?

 

That's MESSED UP. With a capital "F". I wonder what the person who was driving it at the time was thinking for those last 1000 miles or so that it was making all that noise?

I would say, .033" difference in rod journal diameters probably exceeds anybody's best guess of a reasonable expectation of success by polishing. That's about like hitting a telephone pole at 40 mph and wondering if the damage to the paint will buff out.

Since about as far as you can grind a crank is .030", which takes .015" of metal off, and you have a journal that's ALREADY more than .033" worn which usually only occurs on one "side" of the journal (i.e. you'd have to grind the opposite "side" of the journal .033" just to make it back round again, for a total of .066" reduction in diameter) and there's no guarantee that you even measured the deepest damage (it might take ALOT more than that to clean it up), I'd say that one has earned its ticket for a trip to the big crankshaft retirement home in the sky.

Since the bearings spun, the rods are also garbage.

Probably best to consider that purchase of a core as, just a "block", not an "engine".

Time for a complete "kit" rotating assembly.

Likewise, since a main bearing spun, the block will need to be align-bored. Probably cheeeeeeeeeeper to just get another block as well since there's nothing "special" about that one. So it might not even be any good as a core "block".

Pretty much whatever you paid for that, was too much. About all that's any good is the roller cam apparatus (it DID come with that, right?) and the heads (they ARE still the 083s, aren't they?). If either is missing or altered, consider it a lesson in used car-parts pre-purchase evalution.

 

Idk what you can do with the mains but you could take rods down to honda 1.89" journals. Like said it maybe best to find a new setup

 

why bother even messing with it, replacement sbc cranks are cheap and easy to get
, by the time you get that correctly repaired youll spend more money and have a weaker crank that you would have, replacing it, look at this as a great time to build a new 350-or-383

http://www.summitracing.com/parts/SCA-1-91015/

http://www.summitracing.com/parts/SCA-1-91055/

http://www.summitracing.com/parts/SCA-1-40855-1/