I was looking at an engine and the oil flow path described on pp 4-6 and 4-7 of the sedan shop manual is correct.
What is a little misleading is how the oil flows through the filter. The text implies all the oil from the pump goes through the filter element and up the center bolt unless the filter is plugged. I don't believe this is correct. I believe the filter operates in bypass mode. Looking at the system, though, it does appear that all the oil must flow through the filter before finding its way to the center bolt and the rest of the engine. When I checked the spring tension on the check valve, it appears to be very weak (the force to open the check valve would be measured in ounces and not pounds ......so, less than a pound is needed to open the check valve).
In normal operation, I believe the check valve is always open slightly which allows some oil to pass through the filter element and the remainder is bypassed directly to the engine components. If the filter becomes clogged, all the oil would flow past the open check valve and up the center bolt. The inside diameter of the center bolt is 1/2 inch which makes it look like a 1/2 inch pipe. If you go with a remote oil filter system, you would want to choose a hose which flows oil better than a 1/2 inch steel pipe.
After looking at the oiling system, I can see several things related to the oiling system which are important when rebuilding the engine. They are;
1) the check valve in the oil filter center bolt needs to be clean and operational. If you have a center bolt which is dirty or rusty, the check valve may not work properly.
2) the oil nozzle over the primary drive should be in good shape and not have its nozzles enlarged. Doing so may lessen the flow of oil going to the main bearing on the clutch side of the crank.
3) the oil bridge (that tube which goes from the oil filter housing over to the primary drive) needs to be a snug fit and clean. Don't let any gasket sealer or debris clog this area.
4) those rubber washers and o-ring, metal washer, and spring which are around the oil filter serve a very important purpose and must be in place.
Dale
> I was
> also thinking about installing the kit for an external oil filter and cooler.
> But I'm curious: Will the extra oil lines and cooler and stuff add resistance > to my oil pump and reduce oil flow? I didn't do anything as far as rebuilding > my pump goes. It looked like it was in relatively good condition, but I want > to make sure I get good oil flow. I'm worried the extra lines will "slow my > flow".