Why does the oil pressure gauge always read 3/4?
The stock SS oil pressure gauge is completely bogus, since it actually does not use a sending unit but a switch instead. The oil pressure switch is mounted on the back of the engine behind the intake manifold, and is calibrated to close at 4 psi. When the switch closes, it grounds the stock oil pressure gauge through a 68-ohm resistor, which causes the gauge to read 3/4 scale at all times. Factory SEO (Police) cars get a real sending unit calibrated to show a resistance between 0 to 88 ohms depending on actual oil pressure. You can install this yourself if you’re so inclined. Back to the index…
