Here is a breather cover a friend made me with the GT3 valve built into it, the valve is held in with the stock circlip.
http://forums.pelicanparts.com/uploa...1277079570.jpg
http://forums.pelicanparts.com/uploa...1277079513.jpg
http://forums.pelicanparts.com/uploa...1277079526.jpg
http://forums.pelicanparts.com/uploa...1277079555.jpg

Very nice. Quite a "friend" you have there! Such a thing would not be out of place on my old '66 engine!

Another data point.

I went out to my garage and looked at my GT3 engine's cam box oil pump to find that I was WRONG when I said that the cam box oil pump does not connect to the crankcase.

Note pictures of the cam box oil pump. Note the 3 ports, two surrounded by "O" rings and one female threaded that connects to the line going to the oil tank.

The two "O" ringed ports are the suction ports, the one on left goes to the cam box itself and the right port sucks from just below the chain wheel from the chain housing which is directly connected to the crankcase as shown by pencil.

So, a GT3 has a hell of a lot more crankcase suction going on.

http://forums.pelicanparts.com/uploa...1277081826.jpg
http://forums.pelicanparts.com/uploa...1277081842.jpg
http://forums.pelicanparts.com/uploa...1277081854.jpg

CupCar,

The breather piece is very nice. Can you confirm the function of the valve? In my experience with valves in other applications they limit vacuum, some are adjustable others are not. In a perfect world the valve would also vent positive pressure in the event that it overcame the pump (broken ring for example) without something to vent the pressure a seal will be next on the list, not a good option. If you have the tools to check the vacuum on this valve we would all know what Porsche limits the crank case vacuum to.

If this valve serves both functions how do I get one of these fine looking parts?

Stay tuned,

PFM

The valve is spring loaded and "one way" only allowing air to flow out of the crankcase. It is not adjustable and seals with a Viton "O" ring on the piston.

Porsche sells the valves as a screw in piece shown in pictures earlier in this thread.

The breather cap was custom made.

CupCar,

Thanks for the info, so it is an escape path if something goes wrong and the case pressure goes positive. Do you have a part number for the Porsche valve?

So to work well a vacuum regulator should be used in addition to this part to limit case vacuum IF the factory pump at cam speed has enough volume to generate any real Vacuum. Still an important part to add to the system.

Thanks again,

PFM

996.107.491.91

CupCar,

Thanks again, $48.xx for the part is not that bad. I will do a little test on the dyno and see if it is worth the effort. Seal it off and see what if any vacuum I can pull with the 3.6 pump in my 3.1. If it makes some it would be a good deal to add to the mix.

Again any info on getting the part you show above? Built into the cover and all?

Regards,

PFM

Made by a friend's manufacturing company in a short run of CNC parts for himself and a few others, he has no interest in doing more.

CupCar,

Fair enough, tells me I need to get busy. I will only need one as I would not want to build more either.

Stay Tuned,

PFM

It seems to be easiest to make a tubular adapter that would fit in the breather line.

Why not just an inexpensive vacuum breaker in the breather line?