Rebuilding the lower half of the engine and I got a new crankshaft shipped to me with matching bearings. After installing it and torquing to spec, i tried turning the crankshaft with the crankshaft pulley bolt. I got a couple of turns in to begin with but it soon got ceased and I ended up shearing the crankshaft pulley bolt. (I extracted it after throwing my wrench across the garage)

My previous crankshaft was refurbished and had .50mm undersized bearings. The new crankshaft came with standard size bearings. I want to know why it would be so tight? Do I need to replace my connecting rods? Do connecting rods have different sizes?

While I wait for a new crankshaft bolt is anyone able to give me insight into why my crankshaft is so hard to turn?

 

Plastigauge the main and rod clearances.

Plastigauging one of each might be sufficient, if you have micrometers capable of measuring the other journals to determine that they all measure alike.

Short of this, assembling every rod and main cap just snug, and then attempting to turn the crank assembly after torquing each one in turn, might identify just where your tightness originates.

A fresh built block is always tight, but breaking the crank bolt is way over the top.

Your con rods are not likely the problem.

It goes without saying that all rods, their caps, and the main caps should be checked for correct sequence and orientation.

 

Thank you, when I get a new crankbolt I will try and identify where its tight.