My son and I are restoring a 1956 6400 with a 261 engine. (I have a journal in the "Project Journal" section. In any event, we are strongly considering upgrading this to a spin on full flow oil filter. It currently has a by-pass filter on it. This engine in a replacement, made in March 1958. I believe it was a dealer installed engine, but in any case, the engine has no serial numbers stamped on the deck by the dist, so I do know it came from GM parts. It has the dowel in the side and the 1/2" oil outlet and inlet ports. It also has a 1/8" port at the outlet. Someone at some time, probably when the engine was replaced, brazed a "T" in the return like from the filter and connected the oil pressure capillary tube to it. Thus the pressure on the oil pressure gauge is reading from the filter. These are both pretty small lines, so I am fairly certain it is by-pass. I was looking at another site, and there was a photo of a dowel in the side of the block that is almost flush. As I understand, this dowel in this position is for by-pass, and if it is pushed in, the large oil outlet and return ports can be used for a full flow filter. Can someone who knows these chime in and let me know if I am on the right track. How is the dowel moved. Do I just push it in?
