1. “Help please someone!” The timing system of an internal combustion engine might be the most important aspect of its construction. It is responsible for the operation of the camshafts and valves and without a proper set up, an engine will not operate properly or at all for that matter. This is why a lot of people are almost afraid to even look at the timing set on their cars but there is no need to worry.
This thread brings up a very interesting aspect of engine design: interference timing vs non-interference timing. The original poster had the timing belt on his Fiat break and simply wants to know what kind of headache he might be in for. Fortunately for him, his particular Fiat is a non-interference set up.
When the timing set of an engine is operating properly, the valves open and close in such an order that they are “out-of-the way” of the moving pistons. When a timing belt breaks, the operation of the valves goes haywire and the pistons will crash into the valves and can cause some serious damage. This is where the terms interference and non-interference come into play. Simply put, an interference engine has such tight clearances that there is no room for error and if the timing belt breaks, the valves will collide with the pistons. A non-interference engine is built in such a way that if the timing belt breaks, there is enough clearance that valves will not run into the pistons. That is, putting it simply.
To find out whether or not your vehicle is an interference or non-interference set up, the easiest way is to visit a popular forum for your particular vehicle. There is a select group of cars out there (such as the B engined Miatas) that are built non-interference but remember this, this set up is not a safety net and the timing set up of a car is still one of the most important components.
http://www.autotalk.com/forums/garage/help-please-someone-10303/
