Rebuilding an F-head Engine

Page 8: Vacuum Lines

by Eric Lawson

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These photos show the PCV system as I've done it on the engine that I'm rebuilding. I think the arrangement of everything is pretty close to how it should be done. I followed the picture from Brochure 62-17 (see Crankcase Ventilation Tech Tips), photos that I took of the PCV system on Derek's Jeep, and notes from looking at as many 4F-134 engines as I could find.

Vacuum source
This photo shows the bottom part of the carburetor, and the oil filler tube on the right. The vacuum source is in the intake manifold below the carburetor. One side of the T coming out of the manifold, runs to the PCV valve on the other side of the engine. The tiny tube from the other side of the T, goes to the fitting providing vacuum to the vacuum-operated heater air dampers.

The opening on the oil filler tube will be connected to the air filter as a clean air source for the crankcase.

Vacuum line tee
This shows the fuel and vacuum lines after they pass below the water pump to the left side of the engine, and the clamp under the water pump bolt that holds the fuel line in place. Not shown are the S shaped clips that hold the lines slightly apart so that the lines won't get worn if they begin to wiggle due to engine vibration.

PCV valve
The positive crankcase ventilation valve is on the side of this T that runs to a bell shaped fitting on the side valve cover of the engine.

Fuel/vacuum pump
The remaining side of the T goes to the outlet fitting on the vacuum (bottom) part of the fuel pump. The inlet of the vacuum pump is connected to the vacuum-powered windshield wiper. The vacuum pump augments the engine vacuum when the engine is running at full throttle and high RPMs. This keeps the vacuum wiper running at a reasonable rate. -- Eric Lawson

See also Crankcase Ventilation Tech Tips and Windshield Wiper Tech Tips.

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Last updated 28 November 1999 by Derek Redmond redmond@cj3b.info
All content not credited and previously copyright, is copyright Derek Redmond