It's been a while since I got on to this website. I finally picked up a copy of Steven Dove's book "Guide to Buick Preformance Engines", and I've had my nose buried in it for a while. At the beginning of the 455 rebuild section, Dove recommends various sorts of oiling mods, such as drilling out the main and cam bearing oil passages, grooving the cam bearing passages. Since Dove is using a '71 engine block in the book, and I'm working on a '75, are these mods necessary for me to make ?
The 71up block is about the same(all 71up motors have 5/8 pickup tubes and bigger oil holes in the block). All the oil mods help, but don't use a high volume pump(just a standard rebuild kit with a wear plate and TA's adjustible regular). Hope this helps. One more thing you can't use the steel shim gasket on 72up blocks.
