In the fiftires Chrysler did have a bad (and deserved) reputation for weak bottom ends, but that was in their flathead 6 motors. The flatheads had a relatively soft crank that would wear rapidly especially when reved hard.

Actually the 55 or any other Hemi all had a pretty good bottom end (steel crank in a nice rigid block). There biggest enemy is the same as any other engine, lack of oil pressure/oil starvation.

Usually when these engines let loose it was either due to:

1. gummed up oil passages (back in those days the oil that was available was non-detergent), and especially on engines that were used around town and never allowed to full reach operating temperature they would tend to form a lot of internal sludge. Additionally the filter system was a by-pass instead opf full poressure and would often recirulate dirty oil past the filter.


2.low oil pressure (usually caused by excessive wear on the internal componets, or tightly wound cold engine). In the early HEMIs, the oil dain back passages are almost too small. If they are would up tight when they are cold especially when there is excessive wear in the rocker shafts the oil will back up in the heads and result in starving the eninge for oil when the sump goes dry.

If you have an original high milage motor in your car I would strongly suggest you take it easy with it or chances are you will likely find out just how expensive they are to rebuilt. Regardless of the milage on the engine, limit the agressive driving until the engine is fully warmed up (common sense for any engine).