Packard Forum Index » Post-War (1946-54)

The filter canisters should fit but there is a slight difference pre and post war.

Prewar filters usually had the inlet at the bottom and outlet on the side and were initially plumbed into the port which provided oil to the valve lifters. Oil entered the filter element in the middle via the pipe which had several holes in it, was filtered, and then sent back to the engine via the lifter gallery. After several noisy lifter issues, plumbing revisions were made in 40 and 41 and the filter was finally changed to the bypass type that Packard used until the end. To limit flow thru the original filters to roughly 10% after the plumbing change there was an orifice to provide a flow restriction in one of the brass tubing fittings. Also, on some of the prewar filters used with the 356 engines before the plumbing change (and probably on other engines since I believe the filter assys were all the same) Packard introduced a bypass valve in the canister. If the filter was clogged oil would be able to flow thru the valve and bypass the filter element to keep the valve lifters supplied. Your prewar engine filter could be any of those versions.

Postwar filters reversed the flow thru the element by placing the inlet on the side and outlet on the bottom. The restriction on most of the postwar filters was built into the canister via one or two small holes drilled into the center pipe of the filter thus limiting the flow to the approx 10%. You can use the prewar filter on your 46 but you need to be aware of the type and be sure the plumbing is appropriate for the correct inlet and outlet. You can get an idea of the flow via the original tubing for the eight but since the six block is shorter, before you can plumb the filter it will probably need new tubing.

Your 46 six engine would not have hydraulic lifters so the filter return was thru the port supplying the lifter gallery and filter is fully in the circuit. With solid lifters and a limited flow requirement possible thru the gallery, the prewar filter would work as is without worrying about adding the restriction if it is not already part of the existing fittings which I assume would also transfer over.

Here is the typical filter install on a postwar solid lifter engine. Note this filter has the inlet on the side.

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