When talking about the Buick timing chain, visions of Nailhead V8s and torque-monster 455s immediately start dancing in our heads. It's hard to remember Buick as a performance brand, but a Buick timing chain has turned the camshaft in a number of really special motors over the years. But let's give a brief primer on exactly what the Buick timing chain, and it's more recent brother the Buick timing belt, does inside an engine. In a nutshell, a Buick timing chain or Buick timing belt connects the crankshaft with the camshaft, turning the camshaft a specific number of times for each revolution of the crankshaft. The 'timing' portion of the Buick timing belt and Buick timing chain refers to the fact that this interconnection is responsible for the valve timing in the engine. The valves are opened by the camshaft, and the camshaft is turned via the Buick timing chain or Buick timing belt. Make sense? While not set in stone, the basic rule of thumb is that for shorter applications, a Buick timing chain is used, while longer, overhead-camshaft applications rely on a Buick timing belt. This rule is frequently broken by Buick and others, though, so just because you have an overhead cam engine, don't think that you have a Buick timing chain that can be ignored for 200,000 miles. If you happen to have a Buick timing belt instead, your engine won't make it to 100,000 miles without a belt change. That brings us back to the other difference between the Buick timing chain and the Buick timing belt. A Buick timing belt must be changed at particular intervals specified by the manufacturer, even if the belt looks like new. Failure to do so could result in a Buick timing belt failure and subsequent engine damage. The Buick timing chain, on the other hand, can usually be left in service until its clearances are so large that the engine won't run well. Usually by that time, though, the rest of the engine needs some help too, so you can just change the Buick timing chain when you rebuild the engine.