Oil Pressure

[racephotoman]

Running a 425+HP 347 Stroker - 7 QT oil pan. When I start up and cruise for about 15min pressure will stay around 20psi, but dances sometimes dropping to 0 for a brief second and right back up. Warmed up on the expressway I would generally say the pressure basically stays between 20-40psi (most of the time at 30-40 though) while cruising at 2000-2500 rpm - occasionally going over 40psi. I also see at time when I slow for traffic it will drop fairly low. Stupid question - normal for a larger capacity oil pan. I feel confident oil is being circulated, but wonder why the great pressure fluctuation?

Walter

[edwardb]

The extra oil of the 7 quart pan shouldn't really affect the oil pressure, other than perhaps taking a little longer to reach operating temp. Your pressure sounds pretty normal. Once it's warm, a SBF will idle at 20 lbs or maybe a little less. But then go back up with RPM and then in the 40's or maybe more at normal cruise. Some of the characteristics can change a bit with different oils, viscosity's, filters, etc. The occasional dropping to zero is a bit concerning though. I would want to understand that better. Are you sure the gauge is working properly? Have you tried it with a known good mechanical gauge? Is the pickup set properly in the pan, e.g. with the proper height? Maybe others have some ideas for that one.

[racephotoman]

No, using just the (upgraded) gauge(s) that can with the FFR kit. I'm also assuming that the gauge is at the correct spot - will check if there is another optional spot - Assuming it's in the right spot in the pan, could I split the fitting and run a mechanical as well as the electronic for testing - both would work with that hookup???

Walter

[edwardb]

The oil pressure sending unit for a SBF is in the side of the block, very close to the oil filter. It doesn't go in the oil pan. Typically an oil temperature gauge, if used, will be in a bung in the oil pan. But not the pressure gauge. If that's where you have it, maybe could be the cause of your zero readings. But I really don't know.

The pressure gauges are usually pretty accurate and reliable. But like anything, stuff can fail. A pretty standard diagnostic step is to temporarily remove the sending unit and screw in a mechanical gauge to see if the number correlate. But no need to do anything permanent.

[Erik W. Treves]

The sender goes in the block NOT the pan for oil pressure...I had a speed hut oil sender fail at about 500 miles...they replaced it for free

[Johnnymike]

Lots a things can effect pressure. The old gasser boys always said 10PSI for every 1000 RPM.
Pretty unsophisticated but ........

[racephotoman]

I had the senders in the correct location, but decided to change the fitting to the block - started it up and for the first time got a pretty steady psi reading. I also installed a tee to hook up a mechanical gauge as a backup - just purchased the copper line kit (didn't want to use the nylon) and will compare.
Thanks for all the help so far - hopefully I can closed out this tread soon.

Walter