The 1968 Model Year was the first that Porsche had to comply with USA emissions (and safety) laws.
This is also the first instance of the distention between USA and RoW (inland in Porsche-speak).
In 1968 there were the 911 (normal) USA and the 911L USA for the American market.
The RoW cars were: 911S, 911L and 911T.
There supposedly were no 68 RoW 911 (normal).
The USA emissions engine 901/14 has an air pump belt driven off the left camshaft.
It also had a vacuum operated throttle positioner.
The Weber carburetors were changed from 40IDA3C & 40IDA3C1 to the 40IDAP3C & 40IDAP3C1.
There was a vacuum retard on the distributor.
The air pump caused HUGE backfires in the muffler (today it would cause a terrorist alert response).
Porsche got dispensation from the government to disconnect the air pump.
The 1968 911 (normal and 911L) USA emission engine type 901/14.
Standard (65-74) exhaust, air pump, 130 hp.
© 1967 Dr. ing. h.c.F. Porsche K.G.
Note that this may be an aluminum case engine in the image.
Starting with 3280631, the 901/14 crankcases were magnesium.
Schematic.
© 1967 Dr. ing. h.c.F. Porsche K.G.
Left cam drive and chain cover.
© 1967 Dr. ing. h.c.F. Porsche K.G.
Throttle positioner.
© 1967 Dr. ing. h.c.F. Porsche K.G.
Performance.
© 1967 Dr. ing. h.c.F. Porsche K.G.
The performance remained unchanged from the 66 901/05 and 67 901/06 at 130 hp.
The REALLY GOOD NEWS was that Porsche was able to meet USA emissions requirements in 1969
without
the air pump AND with MFI on the 911E and 911S!
The 911S was again imported into the USA with an additional 10 hp (901/10, 170 hp).
The 69 901/09 911E engine was the same engine as the 68 901/14 911 (N&L) emissions engine except
with MFI and another 10 hp to 140 hp.
Best,
Grady