Need help ASAP...Crank won't turn manually after engine install

So I finally installed my rebuilt 304. Everything was going great until I go to rotate it to TDC. I was able to rotate a couple of turns before it seized up. Now it won't turn at all. I took off the oil pan thinking I would be able to see something holding it up, but it all looks pristene. I can't figure out what the problem is and need some direction. Just so you know, its a 78 304 in a 75 cj5. Any help would be GREATLY appreciated.

 

When you say it seized up, does it always stop immediately in the same position when rolling it over, like you can feel something physically hitting an obstruction?
Perhaps it's stating the obvious, but do you have the tranny in neutral?

 

Never mind my last post, you said now it won't move at all. Have you got all the spark plugs out? What happens if you attempt to rotate it with the clutch pushed in?

 

Well I loosened the rockers and that did the trick. But what gives? I installed a summit 8600 cam, new lifters, and new stock push rods. I don't understand whats holding it up?

 

I'm not sure if this is anything or not but I've heard that anything over a .500 lift on stock rockers isn't going to work. It has something to do with the fact that the rockers aren't adjustable and they bottom at just over .500. It's just hear-say, I haven't actually experienced this myself, but if you've got a high lift cam it could be the problem. Another thought... are you sure the cam timing is right? you could have had a valve hitting a piston.

Good Luck.

 

Check if the push rods are installed in the lifters and if one didn't pop out. And not hitting .

 

Well the stupid bug struck again. I had the timing off. Fixed it today. That teaches me for following the Haynes manual and not the TSM. Thanks to everyone...I know this won't be my last post...haha