GMC runs a totally different oil gallery system than Chevy, so ignore the "how to" posts showing full flow conversions on stovebolt engines. It's a shame that most people buy into the myth that an engine needs all the oil filtered all the time. Bypass filters do a much better job of cleaning up the oil, since they take a small volume of the lubricant, run it through a much tighter weave filter media, and actually strain out much finer contaminant particles than a full flow. Anything that passes all the oil needed to lubricate the engine every time it leaves the pump must have a pretty coarse weave media to allow enough volume to keep the engine lubricated. Ideally, an engine should have two filters- - - -a full flow to strain out the "rocks, marbles, and bowling balls" that can damage bearings- - - - -and a bypass filter to catch the stuff that goes through the full flow setup.
Jerry
What I'm interested in is going to a modern full flow system to catch the "rocks" as you say, from getting to the bearings. The original bypass oil filter system on an old 270 is completely different that a modern bypass oil filter designed to catch micron size particles. The original oil filter probably isn't any finer than standard automotive filters used today, any maybe not as fine. From what I've read, changing from a bypass oil filter to a full flow filter reduces overall engine wear significantly.
