Yes, they only go in to the block itself and not through, so they were used to mount something. Just not sure what it would have been. I'm trying to find a '61 Chev passenger car shop manual so I can try to locate a photo of the 235 that went in the cars that year. I'm hoping that might give me a clue as to what would have been mounted there and where, if anywhere, the oil filter might have been connected. I have the side cover off, so I've seen the oil gallery under there and it has a plug in it that I suppose might be used to clean out a portion of the oil gallery. From what I can tell, this gallery comes up from the lifter gallery and is supposed to feed oil up to the rockers. The gallery comes up behind the head bolt to the rocker oiler. The threaded hole that enters on that side is drilled directly into the head bolt location. It could be that there is enough clearance for oil to get around the bolt, but it couldn't be much. I sent Oly some more photos to look at and possibly post that shows exactly what I'm talking about. I haven't seen them yet and haven't heard back from him, so he must be away for a day or two. I suppose the two back threaded holes could have been used to mount the oil filter, but seems a little low to me. By the way, for those of you who are reading this, maybe you can answer a question about the pressure gauge. If I can figure out a way to run a connection fitting to the main oil gallery, can I connect the oil line that runs around behind the engine, the pressure gauge and an oil filter inlet hose at that one plug without screwing anything up like the oil pressure? If it's a pressurized system, seems like this might work. Just have to find a connect that will allow for that many things. I don't want to drill a new hole into the main gallery. Afraid I might screw it up. And in spite of what several have said about not running a filter, I'd still like to have one.
