400 Block...what to look for?

The important thing to remember is that the 400 is a damn good block, no matter what year. If you're looking to build a stout stroker street engine that's capable of an easy 400 plus hp, then any year 400 should be able to take that and more if it's in good condition. If your goal is to build an all out drag racing engine with max wedge port heads that pulls close to 7,000 rpm, then you're going to need a bullet proof bottom end and it may be worthwhile to seek a pre '76 block.

The truth is that there may be no difference at all in wall thickness or casting quality amongst the 400 blocks. But if you're going to push it to the limits of what a stock block can handle, then why risk it? Pre '76 blocks cost about the same. I have a '78 400 in my barracuda and my plan is to build a 500 stroker making roughly 500 streetable hp out of it. I have no doubt that my '78 block would be great for that but I haven't ruled out switching to max wedge heads later on and for that reason I think I may end up looking for a pre '76 block to build my 500 out of.

Good luck :D