Vacuum take off pipes on carbs

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Zaphod
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Vacuum take off pipes on carbs

Post by Zaphod »

My 1990 SE has two take off pipes on each carb just by the inlet manifold. The rubber pipes that attaches to these are totally shot. Where can I find them and what are they called!
Of all the things I have lost I think I miss my mind the most...

1952 MG TD
1957 MGA 1500
1959 Austin Healey Sprite
1975 MG Midget 1500
1990 Lotus Excel

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Lotus-e-Clan
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Re: Vacuum take off pipes on carbs

Post by Lotus-e-Clan »

This might help for names based on function. LB might have/suggest new sources?


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Zaphod
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Re: Vacuum take off pipes on carbs

Post by Zaphod »

That is an excellent diagram to see, as the system on my car is all apart!
Of all the things I have lost I think I miss my mind the most...

1952 MG TD
1957 MGA 1500
1959 Austin Healey Sprite
1975 MG Midget 1500
1990 Lotus Excel

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Lotus-e-Clan
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Re: Vacuum take off pipes on carbs

Post by Lotus-e-Clan »

Zaphod wrote:
Sat Oct 02, 2021 10:28
That is an excellent diagram to see, as the system on my car is all apart!
Yeah Bryan on here did the original diagram in order to get an overview of the system and I added the functional notes taken directly from the textual notes within the Service Notes (no charts in SN).

I've also producd a colour-coded diagnoistic chart for the Vacuum Engine Management system (again, only explained in text within Service Notes) in PDF form which you use in conjunction with the overview diagram.

Clink link here to download the pdf. It's A3 format! So you need a big screen, or an A3 printer, or use the magnify function.
https://onedrive.live.com/embed?cid=752 ... ling="no">

This is a jpg of the chart. Resolution won't be a s good as the pdf above.
Image

You won't need the chart until you've put it back together - it's more useful for fault diagnosis.
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Re: Vacuum take off pipes on carbs

Post by richardw »

This topic is now a sticky. Will copy it across to Technical Articles as well. Great work Peter (and originally Bryan).

Cheers Richard
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barker_001
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Re: Vacuum take off pipes on carbs

Post by barker_001 »

Glad you found the diagram helpful! I replaced the "F-Pipes" (the moulded pipes that connect to each carb) on mine because the originals were split, but the replacement ones (which were some ridiculous price) also split within a couple of years. In the end, I made my own using 4mm ID silicone tubing, which I also used to replace all the other slightly ripe engine management pipework, plus some interconnecting T-pieces, which are available from Halfords or motor factors:

https://www.ebay.co.uk/itm/401073216147

https://www.ebay.co.uk/itm/114603709270

The silicone tubing seems to last indefinitely too.
Bryan

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"Look, there's a Ferrari..."

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Re: Vacuum take off pipes on carbs

Post by Jnh »

Lotus-e-Clan wrote:
Fri Oct 01, 2021 22:17
This might help for names based on function. LB might have/suggest new sources?


Image
Thanks for the wonderful diagram! On item 9, I am struggling to see the correct orientation. Which pipe goes to the connection with the pin hole?
Thanks

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Lotus-e-Clan
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Re: Vacuum take off pipes on carbs

Post by Lotus-e-Clan »

Can't recall seeing a pinhole, but I haven't had the airbox vacuum pipes off for years.

When cold, the air box sensor should allow vacuum to reach / communicate with the diverter valve in the air intake stub (open circuit when cold). When warm, no vacuum should reach the diverter valve (closed circuit when warm).

The valve is situated under the airbox, so copy the pipe connections when looking up under the box.
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Re: Vacuum take off pipes on carbs

Post by Jnh »

Thanks Peter.
The two stubs on the actuated valve are different. One is ‘full bore’, the other is reduced to a pinhole. I’ve connected them with the pipes crossed as shown in your diagram. We will see what happens. (Probably nothing, as they look to have been disconnected for ‘some time’ :D )
Cheers
Nigel

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Lotus-e-Clan
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Re: Vacuum take off pipes on carbs

Post by Lotus-e-Clan »

Jnh wrote:
Mon May 09, 2022 19:25
Thanks Peter.
The two stubs on the actuated valve are different. One is ‘full bore’, the other is reduced to a pinhole. I’ve connected them with the pipes crossed as shown in your diagram. We will see what happens. (Probably nothing, as they look to have been disconnected for ‘some time’ :D )
Cheers
Nigel
Ha! I've never looked down the bore. Please report back, so we all know what's what on that! :)

Worth updating the graphic when we know.
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Re: Vacuum take off pipes on carbs

Post by Jnh »

I will take photos. :D

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