Flip,
In other words, if you are driving down the highway and your timing chain/belt breaks, a zero tolerance motor will hit the pistons onto the valves bending the valves and possibly busting a piston or two, depending on what valves are open when the belt/chain breaks.
VW is one that comes to mind. The engine in the 1997 Scrocco with the 1.8L DOHC engine was infamous in breaking the timing belt. When it happens, about 4 valves would get bent and each valve was $15.00. To repair it, you had to remove the head, replace the valves, possibly the lifters, and reassemble everything. Cost for that engine would exceed $1,000. If you called the dealer and told them your belt broke, you were quoted the price over the phone.
From what I have read, Toyota and Honda also make engines that will self destruct when a timing belt breaks. Since then, timing belts are better now than they used to be, but it is still a possibility.
Most, if not all, of Fords OHC engines with timing belts are non-interference engines, which means if a belt breaks, just set your engine to #1 TDC, set your cam timing on the marks and put the belt on and go on with your life.
I used to date a girl with a Mustang 2.3L. The belt was never changed. It finally broke going down the highway at 85 MPH. Her moms boyfriend replaced the belt on the side of the road and she was back in business. That timing belt lasted about 150,000 miles longer that it should have.
I am pretty sure engine with timing chains are all interference engines.
Tom