Was the engine in chevy k5 blazer a four bolt main?
Not all Chevy K5 Blazers had four-bolt main engines. The type of engine (and thus the number of main bearing bolts) varied depending on the year and engine option. Some small-block V8s used a four-bolt main, but others used a two-bolt main. Larger big-block V8s typically had four-bolt mains. You'd need to specify the year and engine to know for sure.