Jeep Strokers

I bought a crate stroker kit and am assembling the block. When i tighten cap 3 which has the thrust bearing it locks the crank up. Any ideas?

Start by looking at the bearing shells. Are they the correct size? Is the crankshaft standard sized or are the mains ground undersized? Did you measure the crank mains with a micrometer? At that point, did you have all the other caps and bearings on? Were they torqued down? Give us a rundown on the specs and what you did to the crank right before you had this problem so we can get a better idea of what might have happened.