The Official 356Talk Forum

I just installed a 904 style gage from PA Speedo in my '62; it has a healthy 912 motor in it. Just noticed that the max pressure is 70 psi!! Senior moment I guess, and I need to change its range. Seeking advice on what the maximum and mid-range pressures should be for a large pump motor. Thanks for all advice,

Depends on the oil pressure relief valve spring but cold oil pressures with a heavy oil could easily exceed 60 psi if the engine were revved with cold oil.

Most PSI gauges are 0-70 and the BAR ones are 0-5 BAR . 5 BAR is 72.5189 PSI You should be fine. viewtopic.php?f=1&t=9432&hilit=maximum+oil+pressure

Gary,
The pressure at that point (after the relief valve) is supposed to peak at something like 46PSI. If you need a gauge with a higher reading, someone figured they knew more about oil pressure than the factory.

46 PSI?Where did that number come from?

Vic Skirmants wrote:46 PSI?Where did that number come from?

Spec book, pg 25:
"27. Oil Pressure, warm engine at 2,500RPM, 3.0 bar."
Is there a spec otherwise?

3.0 Bar equals 43.5 PSI

Al Cole wrote:3.0 Bar equals 43.5 PSI

Al, when Vic asked, I looked at what was on the desk. I recall the equivalent of "46.8 PSIG" in another shop reference back there in the hall.
Regardless, a 70PSI gauge is gonna be fine.

Atmospheric pressure at sea level at standard conditions = 14.7 psi = 1 atm = 1 bar

At 5 bar, the sender resistance should be about 180 ohms. At 0 bar = 0 psi, the resistance is 10 ohms.

I regularly have about 65/70 psi on my aftermarket gauge when I rev the engine. It idles about 35/40. I believe the gauge was calibrated by the previous owner before installing.