3 vs 5 bearing engine

[Mustlust]

How do you tell the difference between these 2 motors without pulling the sump?

[ramblingboy42]

by their engine numbers and their age

[JDNSW]

All threads (and hence heads and nuts) on the 5 bearing are metric, on the 3 bearing they are UNF with a few Whitworth, and probably a few BSF.

The five bearing has a pattern of reinforcing ribs on the sides of the crankcase that are not on the 3 bearing.

Five bearing are very scarce in Australia - apparently not fitted to any local production, but station wagons and some others were imported built up, and there were later private imports.

[incisor]

and the 5 bearing seems to be the one that puts a window in the block most often

[S3ute]

Hello from New Hampshire.

Beyond what has already been offered - all largely correct - the block colours were also different.

The 3 bearing block was the traditional Admiralty Grey while the 5 bearing block was Ochre Red or some hue thereabouts. The heads might have been painted black.

As also noted, these motors generally didn’t make it into locally assembled trucks.

Cheers,

Neil