MGA 1500 and 1600 crankshafts have a somewhat different form. The obvious visible difference is shape of the counterweights, where the 1500 type is bell shape (concave on the flanks) and the 1600 type is teardrop shape (nearly straight on the flanks).

Photos here are complimemts of David McCoy in Oxford, Ohio, USA.

Crankshaft 1600 Forging No: 12H55LFD69 Total weight, 30 Lbs (worn beyond recommended specifications) Has teardrop shape counter weights.

Crankshaft 1500 Forging No: PG38AX Total weight 29.50 Lbs (with 0.020/0.020 regrind) Has bell shape counter weights.

1600 left - 1500 right

1600 left - 1500 right

1600 left - 1500 right

1600 left - 1500 right

1600 left - 1500 right

1600 left - 1500 right

At MGA engine number BP15GB 6615, the rear oil seal scroll diameter had the machining tolerances tightened up to reduce maximum diameter without reducing minimum diameter. See Confidential Service Memorandum MG212. This was done to avoid metal to metal contact if/when the rear main bearing might become worn. There was no change of part number, so it is intended that the later dimensions will supersede the earlier dimensions. Whenever the crankshaft is serviced the scroll seal dimensions should be checked. If you may have one of the earlier parts the OD of the scroll may be reduced in diameter as noted in the CSM.

The 1500 and 1600 crankshafts are physically interchangeable. For the 1600-MK-II engine (1622cc) the center main bearing journal was made a little narrower so the adjacent cross webs could be thicker (slightly stronger). The 1622 crankshaft can only be installed in the 1500/1600 block if the block center main bearing cradle is machined narrower at the thrust faces.