Hi there! I was once told by a well known Buick guy that the 401 nailhead crank can be swapped into a 455 block. I have looked at the cranks side by side and they seem similar. I never asked particulars on this, but have become curious was the crank fitted in there with really big bearing spacers? or where cast iron spacers made for the application. Asked some bearing manufaturers about this and they were perplexed by my questions. Not sure if this has been posted before on here, haven't seen it. Any input is appreciated, thank you.
I think the cylinder spacing is the same, but they are two different engines. The Nailheads were Y blocks, oil pan rail below the crank center line. Crankshaft mains were 2.50"? The 400-430-455 block was a thin wall casting and the crank center line was even with the oil pan rail. Mains were 3.25". I think the big crankshaft/Mains were made that big to stabilize the block. I don't see how you use a Nailhead crank in a 67-76 Block.
It's been done in the past but I remember no details. This came up in a quick search: https://www.v8buick.com/index.php?threads/destroking-a-455.106945/ https://www.v8buick.com/index.php?threads/main-journal-size-425.81534/ Devon
Was told this application is good for 7000rpms but still at the time I did'nt ask for details was told that h***a rods were used?
