Before I put this on

[gmonde]

it is legal in stock,, I ran the accusump on my amc stocker ,, it was a 3 quart system with the 12 volt electric check valve
when the system is properly charged when installed and during oil changes, it provides oil pressure before the engine is started and protection at the loss of oil pressure

the one way 12 volt check is actuated when the ignition switch is turned on and the oil pressure and 3 quarts of oil from the previous start up is stored is released in to the port that's closest to the oil pump ,this will get you oil pressure on your gauge before the engine is cranked ,,, once the engine is started ,oil pressure and oil is stored back into the accusump and once the hobbs switch has seen the pressure it will shut off the the 12 volt check valve and the pressure and oil will be held at the engine oil pressure running ,,

hope this help the explanation

the hobbs switch activates when oil pressure drops below the pressure designated (they come in 15psi or 35psi