Oil pressure relief vale adjustment?

[Steve Sampson]

I have one of those oil pressure relief valves on the side of my engine O-320 that you turn. I need to drop the oil pressure.

Can anyone tell me roughly how many lbs change one turn should give?

[Steve]

One turn = 2psi. Mine came from ECI with adjuster screwed all the way in. I ended up backing it out all the way, approx 9 full turns. My cruise oil pressure is 87 psi., (the first tick mark after the 80 on Vans gage).

N345SF
Steve

[Steve Sampson]

Steve - thanks for that. Mine came from Aerosport Power and I will probably have to back it off 8 or 10 turns by the time I am finished. Yet on the Dyno it regulated at a sensible pressure. I cant believe it is as simple as 'If we screw this in we will screw the customer up good and proper',but it sure feels that way.

There must be a reason why we both get them poorly set, but I cant find out why.

Thanks, Steve.

[rgbewley]

Steve:

You might also need to look at the Oil Pressure spring. There are three different springs. The 61084 oil pressure relief valve spring is the one generally installed in a low compression type of engine. You might want to verify which spring you have.

Hope this information is helpful to you.

[pierre smith]

Steven have you tried a direct-reading gauge yet? My oil pressure reads low with Van's sending unit. I borrowed a direct-reading gauge from a mechanic friend of mine and after I'd flown and got the engine hot, I taxied in and noted the oil pressure at 1000 RPM. I quickly uncowled the engine and put on the direct-reading gauge and it showed 10 pounds more than my gauge. I just taped it on the forward top cowl.

Regards,

[Steve Sampson]

Pierre, yes I finally got a mechanical gauge on it late yesterday. It read identical to my ACS 3400 system, so from that I deduced the engine pressure is high. Hence the question below. I will talk to Aerosport Power, but the individual concerned has been away.

What I just dont understand is why I get so much higher pressure than when it ran on their Dyno. Interestingly, they got two very different readings themselves. I am pretty sure they adjusted it after the last Dyno run, but I cant think why.

[Norman CYYJ]

Are you measuring the oil pressure with a hot engine or cold,the oil temperature at start up or after the oil has reached operating temperature? All of these will me a huge difference.

[Steve Sampson]

Norman, What concerns me is the oil pressure ( O-320 )is showing as 104psi at about 150/155F at 2600rpm. This is over the normal maximum.

In the factory, on the dyno the engine did 2 test runs of 30 mins at 2600 rpm where it recorded 76psi at 145f and then 85psi at 150F on 100 weight Shell oil. I am using 80 weight Total.

Yes, before you say it ALL the temps are low, but for me it is running at a higher pressure at a higher temp with thinner oil.

It makes no sense to me unless they made further adjustments after they wrote out the test sheet they presented to me with the engine. If so it seems like a pretty daft thing to do, since it only serves to confuse the customer. The point of the docs is to present a consistent history surely.

I also struggle with why the jump from 76 > 85 psi on the dyno.

[Steve]

1. My friend's Aerosport Superior O-360 engine came with the adjuster backed out all the way. He hasn't fired it up yet so I can't post his oil pressure readings.
2. The only oil pressure adjuster spring in ECI's catalog is the 61084.

N345SF
Steve

[tc1234c]

My Aerosports Power O320-D2A engine runs 83-87 psi at 75% cruise. The adjustment screw is all the way out. As I remember I back it out a turn or so before it reached the stop. During take off, the pressure goes beyond 90 psi. I don't remember whether it ever went above 100 psi. At idle, it is in the 60s. I also like to see a little lower oil pressure. But, I may have to live with it.

My oil pressure spring is LW-11713. The oil pressure (rear) shown on my data sheet is in the 70s.