The deficiency of the stock Packard V-8 oil pump had been well established even before production of the Packard V-8 ended in August 1956. Several supposedly "improved" oil pumps were produced by the factory during 1955 & 1956. A few dealer-installed "field fixes" were tried. There was also varient for the Hudson-Nash 320CID (Packard supplied) V-8. Changes were made in the hydraulic valve lifters in an attempt to reduce clatter. The front camshaft retainer plate was redesigned twice in an ineffectual effort to improve oil system pressure.
The effect of this deficient oil pump could be as minor as occasional clacking hydraulic lifters under various, but normal conditions. But a more serious result was internal bearing wear or failure, usually one or more of the front main bearings.
Over the years, several attempts were made by individuals and club organizations to "fix" the oil pump deficiency. Since no satisfactory new replacement for this oil pump seemingly existed, the pump was modified in a variety of ways. However, none of these modifications actually fixed the root problem which was inadequate oil delivery pressure and volume.
Click here for another discussion of the problem and a few previous attempted solutions (courtesy of Craig's 1956 Packard Panther website).