Looking for some advice on the best way to go about repairing vs replacing engine. This is the 5.4 gasoline engine in a 99 F250. Not sure if the sprocket failure caused the problem or if oil starvation did. The engine will run but it makes a lot of noise that sounds like the top end on the passenger bank. Of course it has no power and a very rough idle, it spits and bucks when cranking so the timing definitely seems to be off. I pulled the valve cover and found the sprocket loose (broken welds) on the cam. My concern is that I've read this is an "interference" type engine meaning any loss of timing would likely result in piston or valve damage. Is this true? If so, I guess I won't know the best course of action without pulling the head. Is it worth it? Is it likely I have bottom end damage also? Looking for a few opinions before I go any further. Also, the engine has about 150k on it and was running fine at the time of the failure. Thanks!

 

Leak down compression tester is your friend.
With camshaft at a position where both valves are closed, there should be very little air loss. If a valve kissed a piston and bent a valve or broke the piston, it will be very very obvious.