Turning a crankshaft? Specs?

[TxBlacksmith]

So, I still cant get the bush/bearings out of the castings, so I am buying a hydraulic press. (I figure I can use it for some other things in the Blacksmith Shop).
I went to slide the bearings back on the crank, to see what the fit up was like for use as spares in the future.   Well...they wont slide down to where they need to be!
Aparently, there are some buggered up spots on each end (mid ways down the shaft), that wont let the bearings to pass.  I assusme this happened during removal of the flywheels/bearings etc.
The engine was patially disassembled when I got it. 
So...I figure the best thing to do would be to put the crank in a lathe and turn it? to take out the problems.  I have a freind with a hot rod shop who has a lathe.
I dont want to reduce the diameter down unless I have to...just take off the high? spots that are causing the problems.  I know there are undersize? busings, but I would
rather not go that route unless necessary.
So what are the tolerance specs for the crankshaft?  Suggestions?  And while I am going to be at his shop, what diameter metal blank, would work best for pressing out the bearings?

[dieselgman]

You really cannot grind the main journals on one of these because you must still fit the flywheels afterward and the shaft size out to the very ends prevents any such modification. They can be welded and reground to standard though. On your shaft damage issue, it may just be a very small ding that can be hand dressed. Feel for the tight spot and use hand tools to straighten it up a bit as needed.

For pressing the bearing, make your tooling as close to its outside diameter as possible without creating any friction inside the housing. Most important for the tool is a straight and flat "business" end and a straight and true push on the bearing shell to avoid any deformation.

Besides a careful visual inspection and feel of the bearing face I would suggest the Lister specified dimensions:  a 2" or 50.8mm journal, and the below variables:
(and maximum wear tolerance of .008")



dieselgman

[dieselspanner]

TXB

When we have problems with cutless bearings (in marine prop shaft housings) we use a hacksaw blade, in a handle, cutting on the 'pull' to split the bearing.

Cut it twice, about 1/2" apart then chisel the thin strip out, you could use a copper drift to save damage. it's not necessary to cut all the way through, once you get the split running, then 'collapse' the rest of the bearing inwards.

I realise the bearing shell steel rather than brass, but it ought to work, be patient and careful!

Cheers Stef

[dieselgman]

The Lister CS main bearings have a thrust flange to also deal with. It has been my experience that they are usually not that tight in their housings to require major pressure on removal. Age and gunk/debris may have them securely glued in place though.

dieselgman

[TxBlacksmith]

So far, these bearings/castings have soaked in diesel/gunk for 48 hours, heated with a torch and sprayed heavily with PB Blaster, boiled in super heavy degreaser soap
for over 1/2 hour, and NOTHING has made them budge.   So as of now, the trash/debris whatever is kicking my butt!

I am going to have to have made, a blank to help press these puppies out!