There are some important details in the manual. There is a suggested position for the cam to be in. If you get the cam in the wrong position, it can hang up coming out. You also need to support it properly so as not to damage a cam bearing.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!