Is there a cam-belt or chain in 1994 Astro van and how often do you need to change it?

The 1994 Chevrolet Astro van uses a timing chain, not a cam belt. Timing chains generally last much longer than belts and usually don't require replacement unless they show significant wear or damage.

While there's no specific mileage interval for replacing a timing chain in a 1994 Astro van like there is for a belt, it's typically considered a very long-life item, often lasting the lifespan of the engine (200,000 miles or more). However, it's advisable to have it inspected during major engine service or if you notice any unusual noises from the engine. A mechanic can assess its condition during a routine inspection.