1933 Pierce – converting connecting rods to insert bearings

This information is in PASB 99-5;

Connecting Rod Bearings on “8” and “12” Engines …..
To: (the owner of a ’34 Model 836A)
Your letter asks if the connecting rod bearings in your 1934 Model
836A engine may be replaced with modern shell-type bearings as described by
Eric Rosenau in PASB 80-3.
When this engine was designed, the crankshaft main bearings were laid
out as replacement shell type, but the connecting rod bearings were designed
as centrifugally cast-in-place babbitt, with babbitt thrust shoulders on ei-
ther side of the bearing.
The Pierce ~Twelve”, a later design, did not use the thrust shoulders.
Therefore, it is no great problem to replace the spun-in-place bearings of
the “Twelve” with modern straight shell bearings, but the connecting rod
bearings of the “Eight” require a shell bearing having shoulders on either
side equal to the thickness of the original babbitt shoulder. The rod width
is much less than the crankshaft bearing journal.
Further, the “Eight” rod was deliberately left rough in the big end
bore to form a better bond with the babbitt.
Therefore, in order to use a shell bearing, the rods must be accu-
rately diamond-bored.
The only shell bearing having thrust shoulders to fit this rod is the
Seagrave, made for this engine later by Seagrave, the old parts numbers be-
ing 28201 (upper and 28202 (lower). I do not know who supplied these to Sea-
grave, but suspect that it was the Cleveland Graphite Bronze Division, of
the Clevite Corporation, 17000 St. Clair Ave., Cleveland, Ohio.
Probably the simplest solution is to replace the poured-in-place bab-
~itt bearings and bore them to suit the crankshaft journals. There are exam-
ples of these “Eights” havin,g run a half million miles on such bearings, so
they may be adequate for an antique. If the bearing dimensions are supplied
to the vendor who is rebuilding your engine, little else should be neces-
sary.

PASB 68-1 also mentions the use of insert bearings for Seagrave V-12 for the rods with some machining required.  Seagrave is still in business, it might be worth contacting them.       [email protected]

Dave