There is conflicting information about which of the late 400s used roll pins and which had dowels. The roll pins started in 1977, and all the 1977 W72 400 engines have roll pins instead of dowels. But there are plenty of examples of 400 engines with roll pins that by all accounts should have had dowels. Dowels are most common.
That earlier post by stuckinda60s that mentioned seeing engines that had pins that had cracks is the only time I have ever heard of 557 blocks cracking at those pins that had roll pins and not dowels. I have seen the roll pin engines with main bearing issues, but had not heard of roll pins engines with cracks at the pin. It would be interesting to know what applications those engines that had roll pin were from. If that was common, it is likely a big part why Pontiac went to the XX block on the 78 and 79 W72 400s.
Last edited by Jay S; 11-27-2025 at 01:32 PM.
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