These valves use the same design as the factory part for a 962. They are specifically designed for dry sump engines to prevent the oil from draining back into the engine while the car is parked. All 4 cam Porsche 356s can benefit from the installation of one of these valves into the oil suction line. Reduced oil leaks and less smoking on start up are the result.
On all 4 cam Porsche 356 Carreras the oil tank is slightly higher than the engine. When the car is parked, it’s possible for the oil to flow backwards through the oil pump and into the crankcase. Once the level is over the oil return tubes, it flows into the lower valve covers and finds its way past the exhaust guides (which have no seals like the intake guides) into the exhaust ports…and sometimes even into the header pipes and muffler. The newer, thinner oils make this even worse. The Anti Drain Back Valve has a very low tension internal spring which is just enough to prevent this oil drain back condition. There is absolutely no risk to the engine! Because of the design, should the spring ever fail or loose it’s tension, it would revert to the fully open position.
(Note: This item only includes the valve and sealing ring as depicted. We also have a kit which includes the fittings and oil line. You can view the kit here: Carrera 4 Cam Kit)
Posted by Unknown on 2nd Feb 2016
I saw the Jay Leno show where this product was mentioned and thought it was a good idea. As the owner of a 4-cam Carrera having a way to keep the lower cam boxes from filling up with oil should help prevent a smoky start. The valve is very well made and fits perfectly where the screen used to be.