I'm half way through replacing the clutch in my 07 FXT and have run into a problem I haven't experienced before. The car was running perfectly Friday morning before we started. We jacked the car up then dropped the gearbox and removed the clutch and flywheel.

I installed the new flywheel I attached a dial indicator to check the run-out and I started turning the engine over by hand and it suddenly hit a hard stop. I realised I had rotated the engine backwards, I then rotated the engine forwards but met the same hard stop in the other direction. I did this a couple times but could only get it to rotate about 350°.

My only thought was I must have done something to the timing and the piston is hitting a valve. I removed the timing cover and I double and triple checked it but timing was fine.

I took the flywheel back off. No change.

The car was due for an oil change so I checked the oil level and it was barely on the dip stick but the engine does have several oil leaks mainly from the valve covers. I dropped the oil and it was quite black but no glitter.

I then removed the spark plugs and scoped the cylinders. The resolution is quite low but couldn't see any marks on the piston face or any interference with the pistons.

I then removed the timing belt and found all 4x camshafts rotate smoothly when not opening a valve. I set the camshafts so they were rotating freely which I believe isn't opening any valves. I then turned the crankshaft from the crank bolt but found it stiffer to turn than I remember it should from years prior and it still hard stopping.

I am stumped and very frustrated at this point.
Is there anything I've missed?
Can you guys offer any advice?

You didn't put a pin in somewhere while torquing the flywheel you've forgotten about?

I would have pulled the flywheel back off before pulling the front end apart...

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Balls.

Sorry forgot to mention. Flywheel was taken back off before taking the spark plugs out.

Get to the bottom of it?

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Balls.

The issue you're facing is quite unusual and requires a thorough analysis. Here are some recommendations that might help: Ensure the camshafts are installed correctly as even a slight misalignment can cause binding. Carefully inspect the cylinders for any potential damage or foreign objects that might prevent the crankshaft from rotating freely. Verify that the valve guides are not deformed and obstructing the valve movement. Check the condition of the flywheel and crankshaft main bearings for wear or damage. As a last resort, you might need to partially disassemble the engine for a more thorough inspection. Good luck!