So I ruined my Connecting rod bearings and I had to replace both the crankshaft and the connecting rods. (along with the main bearings and connecting rod bearings.) So i set the crank down and torqued it. it turned fine. I started to change out the connecting rods and turning each one as i go. 1-3 turned fine. 4th one gave me some issues. hand tight it turns fine. torqued to spec and it locks up. At first i thought that the journal was thicker than the first three like a manufacturer Defect, but i swapped one and three and it turned fine even after torqued down. So I figured that maybe its connecting rod, so i put the old one back in and it still locked up. Changed out the bearings and still it locked up.

Im at a stopping point right now, if any of you have an idea what it may be, all ideas will be appreciated.

I don't know if this helps but i also changed out all the pistons rings for all the pistons. The only thing i haven't changed are the pistons.

Thanks in advance.

 

does the piston and rod move freely up and down seperate of the crank? might have screwed up the cyclinder wall....

 

This is just a bare block were talking about that you layed the crank and installed the pistons in? the crank bearing clearances checked out OK, end thrust on the crank is good, torqued down and it spins freely, so far so good.
Now if I,m reading your post correctly you installed #1, 2 & 3 piston/rod assembly and it still turns fine, but when installing #4 it locks up? locks up like locks solid or gets real hard to turn? if all the clearances were checked and correct then #4 would be suspect, possibly a out of round rod journal, rod or crank,, bearing clearance way too tight, anything done to the cylinders or just popped new rings on the old pistons and stuck them back in the old cylinders? possible wear lip in the top of the cylinder that the ring is hanging on. Just a few ideas without actually seeing what I,m working on.

 

Plastiguage each set.

 

was about to post this same thing, don't just assume because it turns its ok, go up to your local parts store and get a few packs of plastiguage, it will save you a lot of headaches.

if your not sure how to use it i will be glad to walk you though it, i might have some pics laying around of motors i built. to do it right you will end up assembling the motor at least twice.

 

Clearances checked out, and yes i just threw some new rings on the old pistons and assembled it. journals and bearings checked out too. Bores are fine. Checked and double checked it. When i say locked up i mean "will not turn" hand tightened will allow it to turn but torqued to spec it locks up. again i have swapped out the other pistons and connecting rod assembly (basically took piston number one out, the whole assembly, and stuck it in number four and it turned fine. even after torque.) I am tempted to change the pistons too. That is the only thing that i havent changed aside from the whole block itself.

 

is each cap on the right rods? or did they get mixed up? u can check it by putting the cap on the rod without the bearing in it and make sure it's smooth where they butt together.