The 226 used a partial flow system, not a full flow, so a plugged filter might actually raise the pressure since oil isn't flowing through the filter. The filter you need will depend on which system you have on the engine. This was a dealer or after market installed item. The one on my 47 Frazer is , I think, an AC system. It uses an AC PF-316 disposable paper filter. Fram Ch-233, PUROLATER P-70FF, ATLAS C-21, SHELL S-11, TEXACO T-11, MOTOR LIFE M-70FF, and UNION OIL PF 316 are all listed as a replacement. This was also a Mopar and Packard filter in the late 40's and 50's.