1971 Body/Chassis FSM

1971-74 F Engine FSM

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Oil Pressure Regulator/Oil Filter System

Fig. 1

Regulator Position

Fig. 2

Oil Regulator Top

Fig. 3

Oil Regulator Bottom


Back when I pulled the engine I removed the oil pressure regulator to clean it up a bit and to see how it worked.

Fig. 1 shows where the regulator attaches to the block. Remove the two 8mm x 1.25 bolts that hold it to the block. Note there is a gasket between it and the block. Disconnect the oil line from the end of the regulator.

Fig. 2-3 show the removed unit. There is not a lot to it but lets take it apart, clean it up and see what's inside.

Fig. 4

Disassembling the regulator

Fig. 5

All apart, and Cleaned


I clamped the regulator in a vice and used an adjustable wrench to loosen the lock nut. See Fig. 4. Once the nut is loose then the adjuster can be backed out all the way. Next will be a spring and then the regulating piston. See Fig. 5. I put the housing in the parts washer, de-rusted it, then sand blasted it. The piston, spring and adjuster/nut were hand cleaned. While cleaning the adjuster I noticed the oil seal was cracked, I'm still looking for one... (Update: found one)

Fig. 6

FSM Oiling diagram

Fig. 7

Pump to Regulator Oil Flow

Fig. 8

Oil Gallery Flow

Fig. 9

FSM Cut-a-way

Fig. 10

Regulator Oil Flow


So how does the F engine oil pressure regulator work? Well first refer to Figs. 5-8 for how the oil flows through an F engine. The oil is sucked up through the oil strainer, into the pump, pumped through the hard line and into the lower engine oil gallery. This gallery runs the entire length of the block as can be seen in Fig. 8. The oil pressure sending unit is screwed in to the gallery to measure oil pressure.

The gallery feeds oil to the oil pressure regulator then splits and feeds the main crank bearings, splits again and goes to the cam bearings then splits again and goes via a copper tube to the head where it lubes the rocker arms.

Now what happens is this: When the engine FIRST cranks over there is NO oil pressure. Refer to Fig. 9. The spring in the regulator keeps the piston seated so that the line to the oil filter is CLOSED. This forces ALL the oil to the main bearings in the engine for startup. Once the oil pressure reaches 44-50 PSI (or whatever the regulator has been adjusted for) the spring is compressed allowing the piston to move off the seat gradually opening the passage to the oil filter as the pressure rises to its maximum. This diverts some of the oil from the oil gallery to the oil filter where it's filtered and returned to the oil pan via the hose that screws into the block as shown in Fig. 6 and 8. One consequence of this type of system is not all of the oil is filtered before it reaches the bearings. So change your oil often! ANY debris left in the system can find its way to the bearings!




1971 Body/Chassis FSM

1971-74 F Engine FSM

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