Join Date: Jul 2016
Location: North Louisiana
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Lots of Pontiac engines were drilled & tapped for 4-bolt caps, but came with 2-boit caps.
All the '70-'74 455's I built to race were that way.
If you run 2-bolt caps, the webs would be stronger if those extra holes were not drilled.
Some buy 4-bolt caps & have the block line honed or bored.
Some recommend putting bolts in the empty holes, to add a little strength, I suppose. I never had any block problems, at the 400hp/500 torque level.