Woogeroo is right about the 4 bolt main being stronger.You might want to keep in mind though that a "4 bolt main" engine will probably cost more to get,and that unless you subject your engine to very hard use or want to run it at more than 5,000 rpm,a "2 bolt main" engine will hold up just fine. The main things to do are to use a high volume oil pump,and the special drive shaft that is required with it,use a good timing chain and gear set,and call the tech line for whatevewr brand of camshaft you choose to use,and let the expert on the other end help you pick the right cam for your use. The right cam makes a bigger difference in the performance of your engine than any other mod you can make.
Also,if you have a "2 bolt main" block,you probably can run the "4 bolt main" bearing caps,but you have to have a machine shop drill and thread your block for the extra bolts,and you must then have the caps torqued down and the block line bored.(lotsa work and money for a little extra security)
This is probably more than you ever wanted to know,huh?
Speed
