P337 Rear vacuum pressure relief valve

[frank.oconnor19]

Just wanted to add on here. The pump relief valves, there are two, one for each engine. On my 1976 the front is on the firewall on the copilot side in the engine compartment. The rear is in the wheel well of the pilots side maim gear. There are tabs on the adjusting wheel that are used to limit the movement of the adjustment wheel.

the rear adjustment in mine was blind. And to see the result you need to start the engine read the gauge and then determine the effect. I was doing this to allow for the lower vacuum requirements once removing all of the gyros.

Hope this helps