adjusting oil pressure and locknut

andrew phillips · #1 06-17-2009, 10:26 AM

Superior IO-360. I was thinking of turning down the oil pressure a bit on my engine as it runs near 100 psi most of the time. I had a look at the adjuster. There is a slot for a standard screwdriver and a castle nut with a pin in it. The procedure is outlined in tin the operator manual. I had assumed that the castle nut was being used as a jamb nut to lock the adjusting shaft in place. My castle nut is about 3/16" away from the block. I don't know if this vibrated into this position or if the nut is there for another reason. Any info would be great!

Lionclaw · #2 06-17-2009, 10:30 AM

If it's like mine, you put a wrench on the nut and turn the nut/pin/shaft all as one. On the inside of the adjuster, there is a spring which rests on top of the threaded shaft and has a ball bearing on top. Tightening/loosening the nut/shaft will increase/decrease the compression on the spring.

Hope this makes sense... Mine is on an o-320, but I'd imagine they are probably similiar or the same.

vic syracuse · #3 06-17-2009, 01:27 PM

They are the same. The nut with the roll pin through it is what can be used to increase or decrease the pressure, as well as the screwdriver slot. There is no jam nut to keep it locked.
Vic

az_gila · #4 06-17-2009, 01:35 PM

...from Sacramento Sky Ranch...

http://www.sacskyranch.com/eng26.htm