Autopsy of 2.2S - Tales of the weird
 

Now this is weird - I rebuilt this motor ~5 years ago and didn't notice.

The right (4,5,6) side case half is a 3R case, and the left (1,2,3) side case half is a 2R case. Aren't they supposed to be the same? If I remember correctly, the 3R would be correct for a 2.2S from 1970, and a 2R case would be from an earlier 2 liter motor.

And I have never heard of a mix & match with case halves being the proper way to go about building a motor.

Sheese!

there are a pair of numbers on the top of the case by one of the perimeter bolts.. are they the same? I belive they're labeled much like rod bolts. I've seen 1R/2R(a 69 and a 70) cases, 3R/3R cases (71), 3R/4R cases (a 72), 4R/5R cases (another 72) and 7R/7R cases (73-77). The casting # on the bottom doesn't mean much.. there's a few things you can infer but not much.

Re: Autopsy of 2.2S - Tales of the weird
 

This is not anomalous. The 'xR' simply denotes the revision to the casting. Each case half is treated as a separate part number. Thus, one case half might be at a higher revision number than the other half, depending on the timing of design changes and production. It doesn't mean you have a mismatched case.

In fact - I've seen far more mag engines with mismatched casting revisions, than I have seen matched ones. I can't honestly think of a matched set off the top of my head.