Rear Main Seal

The road engines of this era just had a slinger along with a scavenger ring with a series of grooves to prevent the oil from coming out the rear.  That works fine when the engine is running, but it will weep if the car is parked on an uphill slant.  The race engines were made with a rear main seal, so this is the standard solution to the problem.  Ferrari changed the design to use a rear main seal with the 275 engine and carried that change forward to the later 330 GT engines.  The left picture is from the 4HL 330 GT parts book.  Part 20 is the scavenger ring.  The right picture is from the 1965 330 GT parts book with part 27 being the rear main seal.

First, the slotted scavenger ring is removed from the crank.  This is just heated to remove it.  Then the remaining flange is machined down to the correct size where the inner ring of the new main seal rides.

Then the block and rear main cap get machined for a place for the seal to be installed.  The red arrow points to the lip that has to be removed.

The seal is identical in size to the one that Ferrari uses in the later 330 engines, but is for a Toyota.  My machinist pointed out that several seals are available in this size, but Toyota's never have a rear main seal leak, so that's the one he uses.