After a secondary timing chain broke due to a disintegrated chain tensioner, I decided to replace the whole engine.There were debris all over under the valve cover, a lot sludge (I am a third owner) and I suspected a severe damage to the valve train, because after the car refused to start, I was cranking it trying to diagnose the problem. First, it did not occur to me that it could be a mechanical failure. Anyway, I was able to purchase a clean 2001 high mileage engine (160k miles) with already upgraded tensioners and primary chain. The engine is in the car an running quite well, although I think that the secondary chains are a bit stretched (the tensioner is pushing the chain above the flat level between the sprockets.
I decided to fix the old engine and either to keep it as a spare or sell it. Out of curiosity I installed the exhaust cam back (without a chain, just to check how many valves are bent). To my surprise the gap on all 8 is between 0.30 - 0.40mm. Now I have a dilemma, should I take a cylinder head off? I would like to borrow somewhere the inspection camera and look inside cylinders if there are any valve imprints on pistons.
Does any one have a similar experience? Broken timing chain and no bent valves?

 

While the AJ27 is indeed an interference engine that is perfectly capable of self destructing with a broken chain but many have survived if the exhaust cam ends up in a good position. Remember, the exhaust cam is not going to keep spinning, it is going to stop instantly with a broken chain.

A single skipped sprocket tooth is going to cause rough running, even extremely rough running. Two teeth is going to involve valve/piston contact. Three is certain death.

 

I've seen USB borescopes/endoscopes on Amazon for less than $20.