Rebuilding my 304 - Has anybody ever encountered this?

I'm rebuilding my 304, have the cam, crank and all the pistons installed with new bearings and rings. When I flipped it over to torque the connecting rod nuts the entire crank seized after I torqued all the nuts. I mean it wouldn't budge at all. So I loosened all the connecting rod nuts and now I can move it, but it is still much more stiff than it should be. The crank throws aren't binding with anything and the piston bores don't show any scratches or gouges that would indicate an issue with the rings. I slathered everything with assembly lube when I was putting everything in and now that I can (kind of) move it everything still feels lubricated. What do you think?

 

Yea I kept them all in order and number punched everything. Main caps are number stamped with an arrow from the factory. I plastiguaged the rod bearings and main journals. Do you mean "adjusted" as in the bearing halves are seated properly on each race?

 

If I take the caps all the way off the rods then I won't be able to return them to the crank once I've rotated it. I loosened them to hand- tight and it'll turn but I'm using both hands and pushing pretty hard to get the crank to turn. When I put the pistons in the bores they all went in easy enough, two or three hits with a deadblow and they bottomed out

 

using a breaker bar and the main bolt I can turn the crank with one hand now, it feels like it should feel (compared to my last 304 build). I'm going to try torqueing the connecting rods front/back/front/back working towards the middle using a 3 step torque process and see where it gets me. I don't want to turn it too many times because I'm afraid the assembly lube will thin out too much for first start-up.

 

Okay... torquing them to just 10 ft-lbs is causing binding.

 

You have something binding up cause it's assembled wrong or machined wrong. Did you measure the rod bearing clearance for each of the rods before you assembled the block? Mains too. Plastigage is your friend here.

I would take it apart, and test every journal with Plastigage - mains and rods. I would also test that the crank and rods move freely when assembled - no rings, no rear main. It will be difficult to judge whether the crank turns freely once you have the rngs in, because of the drag. But it still should turn.

 

I plastiguaged the rods while the crank was in after I plastiguaged and (3-step) torqued all the main caps. I had it all together after it was machined 1.5 years ago and it didn't have any issues so I'm banking on error on my end. I'm going to go remeasure the rods. With the rings on the pistons, I should still be able to turn it over with one hand with a breaker bar, right?

 

You also need to measure the clearance between the rods, and the clearance for the thrust bearing. A feeler gauge works for this. Measure, measure, measure. And measure again. The more you measure and check your measurements, the more likely a good outcome will be. Buy and use as many measurement tools as your budget allows.

 

Well, I don't know. It's been too long since I've had my hands on, and that's a very subjective call. I don't want to guess and steer you wrong. But it clearly sounds to me like you have something assembled wrong, if the force needed to turn the crank goes up as you tighten the rod caps.

 

Okay I have a new theory, as retarded as is makes me sound.

I might have uniformly put every piston in backwards. So it looks like it would be right because everything is oriented the same way, but it's backwards. I think that would explain it. I'm going to blame it on the 100 degree heat.

 

Yep. Thats what it was. Let's not tell anybody about this, okay? haha

 

Glad you got it straightened out!

 

Only one way to learn...

 

Hey, at least you didn't learn after it was all buttoned up!
And it ain't the heat. It's the humidity!