I'm looking into a stock 400 block and plan on a 406 SBC for my winter motor project. I've got most of the parts save for the block and rotating assembly but have come to a crossroads. I've read that the small steam holes of the siamesed block and head plug up being raw water cooled and a blown head gasket is the result. What's the consensus of this and does anyone have any first hand experience? I'm not against a 383 or 396 out of a 350 block if it will be more reliable. I can get 010 high nickel 350 blocks for $200.
Thanks
I built a 400 last winter using Dart 180 heads. After an overheat this summer, I removed the heads to check everything out and noticed a bit of yuck starting to collect at the steam holes. When I asked my motor guy about this he told me it's not a problem, they don't need to flow water well, only let any steam that develops pass to the top. My motor is raw water cooled with salt water.
I put one together about 10 years and 500hrs ago and its still running with no problems.
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