My 318....Is no more..... :(

I doubt it is the cause of your problem.....because once it is bolted down and the shear key is in place it cant really go anywhere.... but it still should not come off by hand.

anyhow, I wouldnt put your attention into that right now...I would keep looking to see where the cause of your problem is.

about the only thing you can do at the point you are at is to check the thrust plate.....to check the cam you will need to pull lifters wich means taking off the intake,to check bottom end means pulling the engine