I have a 425 big block in my 1966 oldsmobile. My motor is stuck all of a sudden. It was turning over then the starter gave out now that i got a new one and my motor is stuck. Can anyone help me?

 

Was it running before? Or were you trying to get it running? Can you get a socket on the crank bolt and turn it? Be sure the starter drive is not jammed up in the flexplate/flywheel ring gear. Might need more info as to what exactly is going on.
Steve

 

 

Its never ran since ive owned it,but i got it to crank over and back fire through the carb. Ive tried the crank bolt and the flexplate. Its just stuck all of a sudden

 

Sounds like you need to start digging. Start with the valve covers and look for anything "wrong". If you dropped a valve it would keep it from spinning. Other than that you may need to dig deeper that that even.

 

I just pulled those today. I honestly dont know what to look for,but i did have play in two of the rocker arms. Everything else looked ok to me

 

Next is pull the rockers and inspect the pushrods.

 

Maybe pull the spark plugs too and then see if it turns. Possible hydro lock?

 

Plugs first. When you say stuck .... what do you mean?

You just changed the starter ... that would be the first place to look.

 

The motor has never run but backfired through the carb...

Possibly the timing chain slipped, and may now have come off completely. I would start by removing all the spark plugs, then use a breaker bar on the harmonic balancer bolt to try to turn it over by hand. If it turns, the problem isn't the motor. If it stops, you've got an internal problem.