400 blocks is there a big difference

400 blocks is there a big difference
1970 to 10 of 71 castings, are these the best???
thanks for any help.

The last 3 numbers of the casting number will be 230. And there are 230 casting blocks without the thick main webs. You have to look. But you still need to sonic check. Older blocks seem to have more core shift. I would not worry much about year and go with the one that sonic checks the thickest.

FWIW my 400 block came out of a 72 truck and the sonic #`s were decent and has been goin strong for 13+ years.............

I sought out a 230 casting in that date range that most recommend - pre 10/71, and it sonic checked about the same as two later ones I've recently bought pretty cheap. From looking at the webbing of both types, I feel any 400 block will probably have similar life expectancy in a street/strip stroker like I'm planning.

If I was to step up the power a significant amount I'd definitely go with an aftermarket low deck block.

From the research that I have done any 400 block would be a better choice for rigidity than any 440 block out there from a stock factory block standpoint, as long as they sonic good.jmo

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From the research that I have done any 400 block would be a better choice for rigidity than any 440 block out there from a stock factory block standpoint, as long as they sonic good.jmo

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X2. If a stroked "B" will get you the cubes you want then it's a better choice (my limit is 470 which is using an offset ground 440 crank) including it being lighter & a MUCH better fit in an A body. If more cubes are needed then go with the RB block, my next one is going to be a 535 (30 over 440 block) . Not sure whether to get a kit (440 source maybe) or an Ohio crank/some eBay chebby rods/& the KB pistons for that