Early Valver clocks Kaput quick explaination

[Langsam 10]

Hiya, Ive taken my Early Valver clocks out due to my speedo not working and a few other things.

 

Ive noticed on the back of the clocks, there is a small cast Ali part with a nipple, what is this for? And surely shouldnt there should be a vac hose connected to it?

 

Also Ive checked the end of the speedo cable that attaches to the clocks and its in good condition, why else would the speedo fail?

 

And also my rev gauge doesnt work either, how do I go about getting this working again?

 

Besides these faults everything else works on them lol.

 

Thanks

[Langsam 10]

Here is a pic of the Ali cast part im talking about. Its positioned near the back of the fuel gauge, but the fuel gauge works spot on.

 

http://i3.photobucket.com/albums/y58/mini101/image_zpse76f5753.jpeg

[davidwort 0]

it's the manifold pressure sensor, used with the speedo sensors signal to calculate mpg by the dash, yes, there should be a vac hose connected.

the rev counter is most likely an unrelated electrical issue, perhaps a wire from the ignition coil used to give the rpm signal has corroded away? worth checking the grounds to the clocks though.

[Langsam 10]

Ok cheers, If I run a vac hose from the Ali part where should it connect to?

[Wullie 1]

This diagram should help, item 10.[ATTACH=CONFIG]75294[/ATTACH]

[Langsam 10]

Thanks Wullie, its rattled my brain a bit, but im sure I can figure it out.

 

So if I run a vac hose from the FEI Unit to T piece off from the inlet manifold then to the back of my clocks, would you say?

 

Where would the grounds be positioned for the clocks?

Edited August 13, 2013 by Langsam

[destructiv dave 0]

For the speedo, have you checked the gearbox end. On the early 16v's there should be a plastic cog.

[Langsam 10]

Ive not yet checked that end, are the speedo cables readily available new?