In what year did Chevy stop using the 4 bolt main?

Chevrolet stopped using the 4-bolt main bearing cap design in its small-block V8s in 1986. However, it's important to note that some exceptions and variations exist depending on the specific engine and application. The transition wasn't a complete overnight switch; some applications continued with 4-bolt mains for a short time after 1986, and some high-performance versions retained them even later.