I was putting my engine together and set the bearing in the block and main caps put the crank in and with the caps hand tight the crank won't spin. Took it all apart crank measures 2.538 inches which is .020 smaller than standard spec. Bearings are all stamped .020 which is also correct. But block journals with bearings installed measure from 2.532 to 2.537 so do you think machine shop failed to machine for clearances or do you think its an issue with the bearings?

 

I'd start with some Plasti-gauge.

 

Won't work there is no clearance at all.

 

i'd bet you have main caps on wrong.if there not on there right,the crank will lock up

 

Then, what is your question?

You see, it's possible that the crank is machined .020 under, and you have .020 bearings. So that may be right, and clearances could be proper. Then you would need to check to see if you have the wrong thrust bearing size. If that checks out, then you may have a bent crank, or you may have gotten your main caps mixed up & they are on the wrong journals.

Just trying to help you see whatever you may be overlooking.

 

Main caps are on correctly. As soon as the caps are bolted on, the crank locks up. The crank is larger than the journals in the block that is why plastigauge is not going to work.

 

are they coated bearings? also measure the mains without the bearings it shoulb be 2.750-2.751 . when you measure them measure in three spots to insure they are round (straight up and down, and then 45* to the left and right) you might need to align hone the block. why was crank cut .020? was there a spun bearing before?

 

Every one who has ever worked with an LS series Chevy makes this mistake at least 1 time. I know I did.

On the main Caps, the numbers 1-4 will be in line with each other and the flat edge facing forward. The number 5 will be flipped around and the flat edge will be facing the back of the engine.

Now if your caps are on correctly with the bearings installed properly and the crank still won't move, then have your machine shop look at it.

Also make sure you got the correct Part number for the main bearings. Just because the bearing is .020 doesn't mean you got the correct bearing for your application.

 

Yes the crank was machined because of spun bearings. The caps are marked with an arrow and the # they are on correct. And the block was line honed. After torquing the caps it seems like the bearings seated them selves completely and we are a lot closer now. But the bearing journals all measure 2.542 and the crank measures 2.538 and that's double the clearance I am looking for

 

[QUOTE=1FastBrick;4924951]Every one who has ever worked with an LS series Chevy makes this mistake at least 1 time. I know I did.

On the main Caps, the numbers 1-4 will be in line with each other and the flat edge facing forward. The number 5 will be flipped around and the flat edge will be facing the back of the engine.
yep.i did it when i built my motor.i had another motor and took the oil pan off of it to find out i had them on wrong.