Quote:
Originally Posted by GRX
The 400 block is stronger than the 389. Generally thicker casting and webbing. I know this because I have had both side by side on my bench numerous times.
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Depends on the year and casting.
Seems a trend that the 59 389, 67 400 were strongest of the lot... my old 68 350 was notably beefier than my 70 350 block. Early 455 seems a bit beefier than later 455's. Per previous post... pre-sono I had a 59 that was .150 overbore(4.21)... what I have now should go 4.25 bore. Deck is thicker than 400 plus reinforcement rib along pan rail.
If I can find time today I'll take some pics of my 59 389 my 69 400 and a 72 455 block. Wish I could easily open the wifes 406... its a 557 block.
About 8-9 years ago all 4, plus a 73 400 were all side by side. Should have taken pics back then.
If I had all 5 to chose from now the strength order would be 59 389 2 bolt drilled, 73 400 2 bolt drilled, 69 400 2 bolt caps 4 bolt drilling, 72 455 2 bolt caps 4 bolt drilled, and the 76 400 2 bolt.
A majority of the 68 and 69 400 blocks are all the same casting and most(all I've ever seen) were drilled for 4 bolt caps. Whether it had 2 or 4 bolt caps depended on application.
The rare 69 and 70 RAV non production blocks were basically the 59 389 casting with revised bell and lifter bracing. The SD 455 was also a "special" casting with similar features. The special 389 (Harvey machine) Aluminum blocks were patterned same as the 59 block. Most 1960 blocks are about the same as the 59 but the deck drillings are different to accomodate the change from reverse cool to conventional cooling that year. 61 was the bell pattern change somewher in late 61 early 62 they changed to "thinwall" casting technique,and 64 added the modern starter pad though b body still used trans mount starter.