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Author Topic: Vacuum hoses  (Read 1324 times)
krede
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« on: June 11, 2016, 08:08:05 am »

On my car that has previously been fitted with twin carbs, there is a separate hose for the brake assistant drawn directly from the manifold. The vacuum tank is only used for the headlights. I suspect this isn't the "original" way the system is designed.

What is the correct way of routing the vacuum lines ?   
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Gib
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« Reply #1 on: June 11, 2016, 03:46:52 pm »

That is the same as my 1.6 logic would say its right direct vacuum to the brakes if you are moving as you are most likely to have the engine running. Head lights could be required when at idle or if the engine is of hence the reservoir.
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Jon Weywadt
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« Reply #2 on: June 12, 2016, 01:57:49 pm »

On my 2.2 there is a valve and a T-piece so that the brakes get vacuum directly, but also from the vacuum tank, if the engine is off. The valve blocks vacuum from disappearing through the carb, when the engine is not running.
I would think that is the safest in order to maintain full braking power. At least for a while, in case the engine stalls while driving.
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krede
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« Reply #3 on: June 12, 2016, 04:49:18 pm »

Thanks for the replies Smiley  John I believe you are right, seems like a good idea to have the tank connected to the brakes as well. I'll get hold of that valve as it's missing on my car.   
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Jon Weywadt
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« Reply #4 on: June 12, 2016, 05:34:28 pm »

Here is a picture of the valve😎
It is on page 84 in Simons catalog and has part number 17-023
« Last Edit: June 18, 2016, 01:28:35 pm by Jon Weywadt » Logged

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roy4matra
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« Reply #5 on: June 17, 2016, 10:33:24 am »

On my car that has previously been fitted with twin carbs, there is a separate hose for the brake assistant drawn directly from the manifold. The vacuum tank is only used for the headlights. I suspect this isn't the "original" way the system is designed.

What is the correct way of routing the vacuum lines ?  

All Murena 2.2 (and as far as I remember the 1.6 too) have a separate hose from the inlet manifold to the brake servo so you have an independent system with full vacuum available for the brakes at all times the engine is running.

The other inlet manifold vacuum take-off for the head lamps goes via a combined tee-piece and one way valve to the vacuum reservoir and the double acting servo at the front for the head light lift and lowering.  The one way valve is so that the reservoir does not drain away back through the manifold once the engine is not running.

This vacuum take-off for the head lamp lift/lower servo also has another tee-piece but with a small third port which is for the inlet warm-up device.  So the tee-piece has two 10mm and one 6mm connection.  The 6mm connection goes to the temperature valve inside the inlet elbow on top of the carburettor, and a second hose from here goes down to the operating diaphragm for the flap in the intake pipe.  When cold the diaphragm flap directs the intake to between the block and exhaust which is warm, but when the temp. valve in the intake elbow operates it changes the flap setting so that the intake only picks up cold air.

Obviously since the 'S' did not have this warm up air system, it does not have these additional connections.  Any Murena modified from the single down-draught carb. to twin side-draught carbs. will probably not have it either but it will depend on just what the person doing the modifications, did!

Roy
« Last Edit: June 18, 2016, 11:05:02 am by roy4matra » Logged

krede
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« Reply #6 on: June 17, 2016, 11:15:08 am »

Thanks Roy that sorted things out.
As I an fitting a turbo to my car the vacuum hose for the brakes will need at one way value at the very least, but perhaps it might be better to rout it to the tank as well to have a reserve for when the engine is under boost.?
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