Vacuum hoses for a late 75 2.0l Porsche 914, Is it ok ? Options

[Villemi]

Hello

I have december 75 2.0l Porsche 94

My car is an US one and had a canister and air pump.

For late 74 diagram it was this one

(IMG:http://www.914world.com/bbs2/uploads_offsite/i48.servimg.com-23807-1640074350.1.jpg)
I don't have any more the canister and the air pump

My car has no anti flash back valve too.

Are you agree with the new diagram for my late 75 car ?

(IMG:http://www.914world.com/bbs2/uploads_offsite/i48.servimg.com-23807-1640039023.1.jpg)

It's difficult to understand when you have a 46years old !!!

[BeatNavy]

The decel valve is not mandatory -- some people remove them, but it does help prevent the MPS diaphragm from blowing on hard overrun (very high manifold vacuum). The MPS under 'normal' driving conditions can have manifold vacuum anywhere from 0 psi in Hg (EDIT: corrected to in Hg) at wide open throttle to somewhere over 22 psi in Hg (EDIT: Corrected to in Hg) during overrun (downshifting). Vacuum pull significantly higher may damage or blow the diaphragm inside the MPS. The decel valve opens up to relieve the vacuum. You can adjust the level at which the decel valve opens. I can't recall where a stock decel valve is set to open -- maybe 20 in Hg?

Some people remove them completely as it brings RPM back to idle levels quickly and can enable faster shifting (e.g., for racing). If the devel valve is improperly adjusted you can get some strange behavior on shifting. Specifically, the idle RPM may hang too high for too long or drop too low or the engine may completely cut out.

Does that help, Villemi?

[StarBear]

The decel valve is not mandatory -- some people remove them, but it does help prevent the MPS diaphragm from blowing on hard overrun (very high manifold vacuum). The MPS under 'normal' driving conditions can have manifold vacuum anywhere from 0 psi/bar at wide open throttle to somewhere over 22 psi / 1.5 bar during overrun (downshifting). Vacuum pull significantly higher may damage or blow the diaphragm inside the MPS. The decel valve opens up to relieve the vacuum. You can adjust the level at which the decel valve opens. I can't recall where a stock decel valve is set to open -- maybe 20 psi?

Some people remove them completely as it brings RPM back to idle levels quickly and can enable faster shifting (e.g., for racing). If the devel valve is improperly adjusted you can get some strange behavior on shifting. Specifically, the idle RPM may hang too high for too long or drop too low or the engine may completely cut out.

Does that help, Villemi?

@BeatNavy 20 psi or 20 in Hg? I think I saw the latter recently on the 1.8L idle issue thread.