LOL, or spray weld and bore back to size

The saddles were probably hurt beyond that point. Not a good idea to move the crankshaft centerline that much... It becomes more than a .005 or .010 short timing chain can compensate for. The bigger issue with a one piece rear seal block, such as a Gen VI, is that the crankshaft centerline moves up, but the rear seal does not... ie: rear seal leak. Boring the main housing bores oversize has become more commonplace with most engines being one piece rear seal. On a Mark IV block, the seal retaining area is the same dimension as the housing bore... when you cut the cap and hone the bore to std. size, the seal area size and alignment is corrected along with the housing bore.

What kind of block is it? It may not be worth repairing. You can machine the block for a saddle but to do that on all 5 is going to be costly. So you need to really consider is the block worth it?

There is no signs of heat damage along the mains either so if they spun, it wasn't for long. I see no evidence of any kind of major mishap. A friend picked it up for me out of state and had his local shop hot tank, check it out and put in plugs/cam bearings. Everything is great except for these odd sized mains.

Have you measured all five bores to see if they are all .020 oversize? I'm sure you can get away with using a Clevite 1748P. The Clevite P series bearings are a steel back bearing, and are probably fine for what you're doing. Only problem is, as I stated above, is that only 1-4 are over size... and you'd have to grind your mains .010... cheaper than another block.

Rear thrust is .020 over also.......

Masch,
Very very common procedure to save a block with very badly damaged main bores. You can only do so much with an align hone. The big rebuilders do this pretty regularly to save blocks and all of the major bearing manufacturers make bearings for this purpose. Same goes with cam bearings.

Unfortunately I dont know if anyone makes a good race type bearing. If anyone, I would bet on King.

Bill Koustenis
Advanced Automotive Machine
Waldorf Md

CI,
I dont think this is the case, but the thrust might be .010 wider. I have done this to several blocks and all five bearings are the same crank journal size.

King alecular makes them:
Main sets with oversize thrusts in .010", .020" and .030" as well as a special .020" oversize outside diameter "line bore" main set for blocks with +.020" oversize housing bore blocks. (write for further details)
Tried to find you a link, you need to probably call them:
http://www.kingbearings.com/bullseye_tolerance.php

Thanks for the info...I guess you learn something new everyday. Ive been in the business over 20 years and have never seen it.