The B.B. in the title represents that this is from the archive of the late Bill Bently, who ran a flathead Q&A informational site before he passed away. All threads from this source will be titled using the B.B. identifier on this site. We’re archiving some of the threads, so that his work is not lost or forgotten and so they will continue to educate flathead enthusiasts for years to come.

I don’t know if this subject is covered on the techno site or not. Perhaps it should be. The 4″ crank fits the 59A block just fine. The only clearance problem I have seen is at the oil pump pickup tube when using the newer M19 oil pump and truck pickup tube. The rear counterweight can make slight contact with the tube.

You should use the original main caps for the block and the 59A main bearings. The 59A rods can be used, but the pistons must be for a 4″ stroke and the bearings must be the Full Floating design.

You can also use the 49 up Ford or Merc rods with the insert type bearing shells. These bearings are less expensive and do not require the extra skill and effort of “fitting” the bearing halves to match the rod and crank. For this reason I recommend the use of the newer rods to most do-it-your selfers. That said, the Full Floating design is superior in all aspects of performance criteria.

Most 4″ cranks have a short seal collar in front of the timing gear which must be removed in order for the 59A crank pulley to fit, since that pulley has the seal contact area as a part of the hub.

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