The 1953 Powerglide engine is a full-pressure oil system, as you have determined. It doesn't matter if this is a '53 engine, but it either needs slots in the head cover, or a vented filler cap, as mentioned previously. I think the vented cap was original, but memory is foggy on that point. The description of the inside of the draft tube by truckernix is correct, and the tubes do get plugged. I think the parts cleaner is a better choice than the 'burn barrel', but I know the process, and it works. Heating the tube with an acetelyne torch, or a propane torch, will accomplish the same thing, if you can stand the smoke, and don't mind painting it afterword. If you use an acetelyne torch, go carefully- remember you aren't trying to melt it.
The oil pressure should remain close to 30 PSI warm, if you are certain it is a '53 PG engine. If it is the Powerglide engine, I think it also should have hydraulic lifters, if memory is correct. Maybe someone else can be more specific on that point. The occasional drop in oil pressure is cause for concern, although 15 PSI I think is sufficient to avoid engine damage unless you are running it under full load. Since you say you have 30 PSI at idle speed, that would seem to eliminate main bearings as the cause of low pressure, so the pressure relief valve in the pump might be a suspect. Having said that, I don't remember if that valve is inside the pump, or under the cover on the manifold side of the block. Foggy memory again. I'll see what I can find on that point, but I'm sure someone else will provide the answer.
Harvester
