Re: Getting new tires on a 34

Posted by Peter Hartmann On 2008/8/20 0:19:38

You think I have a dim view of poured babbit in Packard connecting rods? If you want to see a dim view of poured babbit in Packard connecting rods, suggest you read the engineering reports on them. Plenty of reproductions of these reports floating around. My favorite is one that GMC did, comparing the early 1930's Buicks to pre "insert" Packards.

Interesting story behind this - General Motors was smart enough to figure out they could get by with the cheaper "poured babbit" ( and did so clear into the early 1950's on Chevies and Buicks !) IF they kept the babbit layer VERY VERY thin. The thinner the babbit, the less likely it is to start pounding out (and, of course, the less likely the crank-shaft will survive once the babbit starts to come un-glued).

Packard engineers tried VERY hard to make poured babbit rod bearings work as highways improved and cruising speeds rapidly rose. They went to all kinds of expensive "fixes" that didn't solve the problem. Ever seen the beautifully machined "finned" rods on the early 1930's Eights and Super Eights ? The full flow oil filters ? The full flow oil coolers ? NOTHING worked to save poured babbit rod bearings.

The "sintered copper lead" precision insert type rod bearing on all senior Packards from 1935 production on (until "senior" production ended with the destruction of "senior" production facilities in 1939) was the correct answer then, and remains so today.

As bad as poured babbit bearings were, once road speeds started increasing (reflecting the vastly suprior highways of the early 1930's) poured babbit in 1935 or later Packard con rods is a DISASTER. Again, the thicker the babbit bearing layer, the faster it will "pound out", destroying the crank-shaft.

So - the answer to your post is - don't blame me. I was never a Pacakrd or GMC or Federal Mogul bearing engineer. Blame THEM for the various technical papers that confirm why NO automotive motor ANYWHERE on the planet today (and that includes cars, trucks, boats, piston aircraft, etc.) would think of using this fragile form of rod bearing.