The Stovebolt Site Forums The Parking Lot Big Bolts 2 speed rear vacuum lines

The switch handle is on a rod that goes through the firewall, a linkage connects to the vacuum valve on the frame. When the handle is turned the valve moves up and down and switches the vacuum and the speedo gears change at the same time. A large vacuum line runs from the manifold to a junction on the firewall that supplies vacuum to the brake booster and rear axle valve. All of these lines are larger than a pencil. There is a smaller vacuum line that comes into the cab to rum the windshield wipers.