Ford V8 Flathead Bearing Specifications

Standard Specs for Crankshaft & Connecting Rod Journals

Use the following table to check the original standard bearing journal specifications for wear. If the engine has been overhauled and the bearings replaced, it may have had undersize bearings installed. These are usually marked with the undersize on the back side of the bearing. For instance, if the crankshaft main bearing journals were ground down ten thousandths of an inch, the replacement bearings would be marked ".010" on the back side.

Engines manufactured before the late style 1949 (or the 1948 trucks) had the "floating" style rod bearings. These were not keyed to the rods but could float and rotate freely between the rod opening and the rod journal on the crankshaft. Since they have a bearing surface on both sides, there are no markings on them, and they would have to be checked with a micrometer for clearance. Check bearing journals with a quality micrometer. Take four measurements on each journal (checking side to side and also checking 90º apart on rotation). 

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