Join Date: Jul 2016
Location: North Louisiana
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As mentioned, the 500557 block is one to avoid. Another is the 568557.
Also, some of the XX 481988 blocks used in '78 & '79, do not have the holes drilled for the 2-bolt motor mounts.
Some prefer the common '71-early '75 481988 blocks. The '70-up blocks, which have all 5 motor mount bolt holes, have advantages. They can be used in cars that use either 2-bolt or 3-bolt motor mounts. This is a good selling point, for anyone who may consider selling their engine, at some point in the future.
If you're not gonna add 4-bolt main caps, I've read that it's best to use a block that was not drilled for 4-bolt caps. But, some say that if you do decide to use the 2-bolt caps, it's best to install some allen head studs in the open holes. I have no idea if this actually helps strengthen the webs or not. ???
2-bolt caps with ARP main studs are said to be plenty strong for up to 600hp builds. So, some probably pay extra money to run 4-bolt caps they don't really need.