64con

Recently I purchased a used gm57lg block. When installing my crankshaft I used plastic gauge to determine the crankshaft fit. I could only get the 4th bearing cap to be acceptable. All the rest were over .006.
I decided to take my block and crankshaft to a machine shop to get things checked out.
The machine shop told me that my main bearing caps must have been from another motor and they had no caps that would fit rendering my block useless
Could this be true? Can't I get a set of billet caps and get the machine shop to line boar the new caps.
Makes me wonder about the machine shop I'm using.
Any help/ advice would be great.

427Hotrod

Usually you can just mill a few .000's off the bottom of the cap and then re-do the line bore. Wouldn't think it could be too big of deal. I'd wonder about them also....

JIM

Easy Rhino

While it could be true that your caps were not original to the block, I agree with Jim, in that skim cutting the cap seating surfaces and line boring the crank bosses should bring the caps in nicely.

Ask a second machine shop.

64con

Thanks for the great info.

Pop Chevy

That's BS... Find a new machine shop - now !! Billet caps are nice but not needed under 400 hp.

DZAUTO

I'm in total agreement.
This method for line boring/line honing is a VERY standard machine shop procedure for truing the main bores of a block.
And yes, you caps COULD be from another block. Caps can be mixed and matched within certain limits. it the cap, cap register (that's where the caps fit in the block) and block are MINIMALLY, and I mean MINIMALLY out of alignment, any good machine shop that regularly does block machining should be able to make everything fit perfectly.
So, as mentioned, check with another machine shop.
I've even done so much as to pull 4bolt caps from one block (from a 366 truck block) and have my machine shop fit, machine and install them on a 2bolt block.