I've got an l28et engine that has been sitting for an undetermined amount of time and in unknown condition. I poured some automatic tranny fluid into the cylinders to try and loosen things up and then put a bit more in a few days later.

Today I tried cranking it by hand and I've run into a problem. Using a breaker bar I can get the crank bolt to move but it's pretty tough and the pulley doesn't move. I removed the bolt and it looked fine with no metal shavings on the thread (was looking to see if I was stripping the threads). The car is an automatic so I can't rock it back and forth to try and break it loose. I'm at a point where I could continue with the breaker bar and have one of 2 results. Either it cranks or I strip the threads. Do I have any other options (other than trying to start it with the ignition)? Or am I at the point where I need to tear it down?

You might try leaving the spark plugs out, if you didn't. Is the engine and trans. still in the car?

Bryce

Tried with plugs out and yes, engine is still in the donor car.

Just went through this myself Ptero,

My donor motor sat for over 9 years and it was completely locked up. After I tore the whole thing apart, I saw rust everywhere from all the years of condensation.

I had to literally knock the pistons out with a small sledgehammer from the bottom side of the motor once the crank was out of the way. (after it was soaked in BP Blaster for two weeks)

No big deal because I planned on replacing everything anyway, and there were no appreciable grooves etched into the cylinder walls considering the rings sat in one spot for 9 years.

I wouldn't kill myself trying to turn the crank if she's been sitting for a really long time, especially if you plan on rebuilding her anyway.

Hope this helps....

Try pouring diesel fuel over the motor with the valve cover off, allow that to soak, and try to break it free. It's kinda an old school trick that's worked for me before.

Chase

Look through the plug holes into the cylinders. If you can see rust in any cylinder (even just one), it's going to have to come apart. If you try to force it over serious rust in the cylinders you're just going to break something.