Sensing Manifold Pressure

From Bondline

One way to pick up manifold pressure, either for a gauge or an electronic ignition system, is to use the otherwise unused fuel injection port on our normally aspirated airplanes. The photo depicts one way to do it, with a hardline attached to the port on the #1 cylinder, routed and supported with adel clamps on the #3 pushrod housing, and then to a bulkhead connector mounted to the rear baffle.
Aft of the rear baffle, a flexible hose is used to attach to the gauge inside the cockpit or other pressure sensor as needed.