I-8 crankshaft and bearing questions

['51 Special]

I recently found a needed 263 crankshaft for a manual transmission car. The engine was frozen due to sittting for years with no manifolds, but the crankcase had a combination of oil and water sufficient to keep the crankshaft bathed in oil the whole time. I just unbolted and lifted it out. I kept the main caps, along with all the bearing inserts. Whatever killed this engine, it wasn't the bottom end.
The rods all had .001 undersize bearings. The mains have me puzzled. The main caps each had a .003 shim under the bearing insert. All of the main inserts, but one, appear to be full size. The tabs on the No. 1 main bearings each carry the number "06," which I understand to mean a .006 undersize. My questions:
1. Does this combination mean Nos. 2, 3, 4, and 5 main bearing journals are ground .003 undersize, and No. 1 main bearing journal is ground .009 undersize, or something entirely different?
2. If the No. 1 main bearing journal is already ground .009 undersize, does tht mean it is trash, or does anyone know of a seller offering a .010 or smaller undersize bearing for the 263?
3. I cannot find any mention in any of my books of the use of shims under a bearing insert to match an undersize journal to a larger insert. Is anyone familier with this technique?
I appreciat the thoughts of anyone who has experince with these engines. Thanks for your help.
'51 Special

[CNC-Dude]

Shimming the main caps was a common way back in that time period to adjust the bearing clearances as needed. The Chevy Stovebolt 6's of that same era came from GM that way. Maybe someone thought they were doing it like other engines were done. Sounds like it could have been a garage fix and the original crank was replaced. When the original crank was removed it was discovered to be a factory blem with undersize journals and a correct standard crank replaced it, they didn't replace the bearings so they had to shim the caps to adjust the clearances. The best way to determine your specific needs is to mike the crank journals and see exactly what has been done to your crank.

['51 Special]

I recently found a needed 263 crankshaft for a manual transmission car. The engine was frozen due to sittting for years with no manifolds, but the crankcase had a combination of oil and water sufficient to keep the crankshaft bathed in oil the whole time. I just unbolted and lifted it out. I kept the main caps, along with all the bearing inserts. Whatever killed this engine, it wasn't the bottom end.
The rods all had .001 undersize bearings. The mains have me puzzled. The main caps each had a .003 shim under the bearing insert. All of the main inserts, but one, appear to be full size. The tabs on the No. 1 main bearings each carry the number "06," which I understand to mean a .006 undersize. My questions:
1. Does this combination mean Nos. 2, 3, 4, and 5 main bearing journals are ground .003 undersize, and No. 1 main bearing journal is ground .009 undersize, or something entirely different?
2. If the No. 1 main bearing journal is already ground .009 undersize, does tht mean it is trash, or does anyone know of a seller offering a .010 or smaller undersize bearing for the 263?
3. I cannot find any mention in any of my books of the use of shims under a bearing insert to match an undersize journal to a larger insert. Is anyone familier with this technique?
I appreciat the thoughts of anyone who has experince with these engines. Thanks for your help.
'51 Special

[alleycat]

This is certainly a bit odd, the boys at Buick did the bottom end of the 263 (the whole engine for that matter) to be "moderen" and do away with shiming the bottom end to get a correct fit. I've pulled down a lot of 263's and never found shims, dos'ent mean that they did'ent do it in order to make a block/crank combination work. I would never try to make that crank work in your block the way it is. Have it turned .010 under on both the mains & rods. You can get bearings from Egge. It should then go right into the block, live long & work fine. Alleycat

[alleycat]

After thinking a little bit, this could be a early 263 and the 1950 263 had the best rods in it. You may want to go back and pull the rods as well. The early rods are VERY hard to get and if you want to build a really hi perf engine, these are the rods to have. alleycat