i was just wondering..
how common are 4 bolt main 400 sbc's?
are they worth searching out over the two bolt mains?

if anybody has an info on the amount of blocks made that are #3951511 (4 bolt main) and the #3951509, #3030817 (two bolt main), it'd be appreciated.
Eric.

 

4 bolt 400 blocks are out there but they're not as common as the 2 bolt ones. Most of the time a 2 bolt 400 block is prefered. The web under the main caps is stronger with 2 bolts. If you're really worried about strength then you can stud the mains or install splayed caps. If you really think you're going to produce so much power that you may hurt it then don't even consider a production 400 block and go and buy an aftermarket one.

The 509 block is the most popular and easiest to find.

 

Thanks for the info, i had forgotten about the web under the main caps..