I have a 4 bolt chevy 454...std bore.

I siezed the bottom end of it last summer. I had the forged crank turned 30 over on mains, and 20 over on rods.....the block got line bored, and rods resized.

Crank measures out to .027 and I have .030 bearings, but clearances are showing .0015 or .002 at best on the mains. Rods are .003 (ideal) with a .020 bearing. (Using tools, not plasti-gauge)

What do you guys suggest to do? Re-line bore the block? Turn a thou or 2 off the crank? Or just run it?

This is a mild build that's going in a cruiser.

Buy .030X bearings for the mains and re-measure. I know you don't want to hear that but... 

King MB-5147HP030X = .029

First off.....

You had the the crank ground undersized, not oversized.      Oversized bearings accept an undersized crank.  You said you're using measuring tools I stead of plasti guage....what size is the crank?  Did they truely take it .030 under or did they take it .028 or .029 under?

The "x" in x bearings indicate an X-tra .001" of clearance.....which based on your numbers, may still be on the tight side.

Always check the work of the machine shop....my experience has been that more often than not, they fawk everything up.

There are specs for rod and main bores withoutthe bearings in yet....confirm that they didn't fawk those up.  While you're at it, check cam to crank distance and make sure they didn't move the mains too far up in the block....measure this at the front and the back to make sure they bored the mains straight.  Then do the math and see who screwed up what up....clearly, something isn't right

First off.....

You had the the crank ground undersized, not oversized.      You said you're using measuring tools I stead of plasti guage....what size is the crank?  Did they truely take it .030 under or did they take it .028 or .029 under?

The "x" in x bearings indicate an X-tra .001" of clearance.....which based on your numbers, may still be on the tight side.

Always check the work of the machine shop....my experience has been that more often than not, they fawk everything up.

I agree. Forking machinists 

Then they Fawked up the crank.  And based on the fact that you have any clearance at all and the crank still turns in the block, the Fawked up the block too.  A .027 under crank with a .030 bearing should have 0 - .0005" clearance....not .0015-.002 or whatever your measuring.  A correct crank in a .030 bearing should have .003-.0035 clearance....but based on what you're saying....if your crank was a true .030 under, you'd end up around .004-.0055". 

Fix it right

This is how we came up with the clearance numbers..

-Mic'd the crank
-Then zero'd the bore gauge in the mic
-Torqued the mains down with the bearings in
-The difference the bore gauge showed determind the clearance

Yup....my logic is backwards. I'm still learnin. Bare with me.

Brad your thinking of the crank in terms of the bearing, if they cut the crank and it is .027 that's closer to a crank that was cut to .020! That's why your math isnt adding up! if it was over cut it would be .032, and closer to a crank that was cut to .040...hope this helps

wouldnt cutting the block yield a different timing chain set? I would say at this point i would have the crank turned!

He needs to measure and measure some more and see where the errors (yes, there are several) lie, and have them corrected. 

wouldnt cutting the block yield a different timing chain set? I would say at this point i would have the crank turned!

yes, but the block has already been cut....so first step is to see how bad they dicked that up....check diameters as well as alignment (referenced off of the cam journals, for lack of a more reliable reference in this case).  Also, was it decked or bored?  If so, it's very critical that the mains were
Done straight, or all other work (which SHOULD be referenced off the finished mains) will be inaccurate.  All of this stuff needs to be checked before thinking about putting it together.

are you getting a consistent measurement in all of the mains? Is that something that they got right? Or is it tapering down?