Looking at the newer oil pump Update kit from Pelican Parts, it seems more confusing.
First of all I must know whether I should replace both the 2 oil releif springs, pistons and nuts. How about the spring guide ?

My engine is a 1974 911 2,7 CIS Carrera.

1) In the Update kit there are 2 different springs, one for the 911/911 Turbo 65-77 etc., it states that 2 pcs are required but there is only 1 pcs in the kit.
The other spring is for 911/911 Turbo 78-98. PART Nos : 901-107-531-01-M260 and 930-107-531-01-M260.
Do I need to buy one more of the 901-107-531-01-M260 ?

2) In the Update kit there are 2pcs of Oil pressure relief pistons for 911/911 turbo 74-89, Part No. 911-107-512-00-M260, and 2 pcs of Oil pressure releif caps for 911/911 Turbo 71-89, Part No. 999-064-026-02-M260. These are clear in that 2 pcs are required for each part. OK.

3) How about the Oil pressure relief Sleeve. There is only 1 pcs in the update kit and it says that this for the 911/911 Turbo 78-98, Part No. 930-107-533-00-M100.


So what shall I do ?
Do I need an extra spring with part No.901-107-531-01-M260 ? Do I need the releif sleeves or they are for other models as the host says ?

Please someone helps as I think there might be some faults with the contents and descriptions of the parts in the Update kit.

My best guess is that I should replace both oil relief mechanisms with 2 springs, 2hexagonal nuts and 2 pressure relief pistons and NOT to place the oil pressure relief Sleeves that is for other models.

The reason for the drilled hole is to allow any extra oil from the pressure release piston to travel back to the intake side of the oil pump.
The closed hole is to block that same oil from going back into the crankcase.
The whole idea is to reduce the amount of oil going into the bottom area of the crankcase and effectively reduce the amount of work the pump scavenge side has to do.
Bob

Does this relief upgrade apply to older pumps too?

The long spring and the guide pin are for the pressure relief piston, the shorter spring is for the safety valve. The new pistons that came with the kit are used.