Thread: Sbc 400 block 3951512

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Is the sbc block 3951511 a good 400 block? It's a 4 bolt main and is bored 040 over. I can buy it from a guy for $350 is that a good price? Thanks

From a strength standpoint, the 4-bolt 400 block is inferior to the 2-bolt 400 block because of thinner webbing at the bottom end. You could end up running over the crank. The other reason I would not buy this block is that it is already +0.040", so the only overbore left is +0.060" and I would not run a +0.060" chevy block. When the walls get real thin, the vibrations set up by the rings running against the cylinder bore will separate air and water in the water jacket on the other side of the wall and prevent cooling water from getting to the metal to cool it, thus you have an overheating motor. This was proven by Smokey Yunick after he cut a block apart, installed glass windows so that he could actually see what was going on and ran the motor. Thicker cylinder walls will cancel the vibrations, while thinner walls will cause overheating. You can read this for yourself in his book, Smokey's Power Secrets........I would say this block is worth the price of scrap.

Now, maybe you have enough valid information to make an intelligent decision.

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