Gauge of pipe from carb to vacuum advance

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Sir Brixalot
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Gauge of pipe from carb to vacuum advance

Post by Sir Brixalot »

One for the obsessives!
My vacuum advance doesn't seem to be working. I tried sucking on the pipe but because it's braided I can't get a vacuum. Tried sucking directly on the vacuum advance but then I can't see what's going on in the distributor and finally the pipe I got was too small. Anyone know the gauge offhand?

E D I T: pipe was not too small. I didn't realise that it had to be pushed into rubber sleeves at either end
Last edited by Sir Brixalot on 02 Dec 2016, 09:44, edited 2 times in total.
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Re: Gauge of pipe from cae to vacuum advance

Post by BOXY »

My vac tubes are 4mm OD nylon with short bits of 4mm ID rubber hose to act as joints at each end.
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Re: Gauge of pipe from cae to vacuum advance

Post by Oldiebut goodie »

^^^^WHS
2mm ID 4mm OD aren't they? Not normally braided though? Or are we thinking of two different pipes?
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Re: Gauge of pipe from cae to vacuum advance

Post by Sir Brixalot »

They're braided each end. Thanks I'll get some pipe now
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Re: Gauge of pipe from cae to vacuum advance

Post by itchyfeet »

Use 3.5mm for a nice tight fit?
https://www.brickwerks.co.uk/vacuum-hos ... braid.html" onclick="window.open(this.href);return false;
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Re: Gauge of pipe from cae to vacuum advance

Post by Oldiebut goodie »

That is only covering the rubber joint! Doesn't need to be braided, it doesn't serve any purpose! Braid is to prevent swelling/bursting which is unlikely with a vacuum.
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Re: Gauge of pipe from carb to vacuum advance

Post by itchyfeet »

no doesn't need to be braided, but if thats what's readily available then it does no harm.
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Re: Gauge of pipe from carb to vacuum advance

Post by Sir Brixalot »

Just ordered the bits that Boxy suggested. I'll see how they go first
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Re: Gauge of pipe from cae to vacuum advance

Post by bigherb »

Oldiebut goodie wrote:That is only covering the rubber joint! Doesn't need to be braided, it doesn't serve any purpose! Braid is to prevent swelling/bursting which is unlikely with a vacuum.

No, but that is what they came out of the factory with if you want to keep it original.
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Re: Gauge of pipe from carb to vacuum advance

Post by itchyfeet »

I think 4mm will leak when hot

Brickwerks wrote:Vacuum Hose - 3.5mm yarn braid

Best Quality.

Suitable for connecting 4.0mm vacuum lines.

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Re: Gauge of pipe from carb to vacuum advance

Post by Sir Brixalot »

OK IF missed that. I just got a delivery from BW today and they had sent me the pipe but I did'nt realise it was meant to run ino rubber joints. I always seem order in dribs and drabs and the postage factor kicks in. Took your advice and got some 3.5mm from ebay
Last edited by Sir Brixalot on 02 Dec 2016, 08:13, edited 1 time in total.
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Re: Gauge of pipe from carb to vacuum advance

Post by 300CE »

I've got a 4mm i/d on mine with a polyester silicone compound - was using 3mm before but collapsed under suction on longer runs. I'm using a Powerspark vacuum advance which has a slightly thicker nozzle than the Bosch one and run a Weber carb and it seems to be a much better fit:

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Re: Gauge of pipe from carb to vacuum advance

Post by itchyfeet »

Sir Brixalot wrote:OK IF missed that. I just got a delivery from BW today, I always seem order in dribs and drabs and the postage factor kicks in. Took your advice and got some 3.5mm from ebay


Should have said this should just be used as joiners to plastic pipe for long runs.
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Re: Gauge of pipe from carb to vacuum advance

Post by CovKid »

I can kind of see the thinking on keeping things looking stock but lets face it much of it wouldn't cut the mustard against modern materials plus who is going to give a fig that the vac pipe isn't original. No braided stuff in mine. It never lasts long in my experience anyway. I was forever replacing it on my bug and bay. Rots quicker than, well, a rotty thing. Not everything VW fitted as standard was brilliant. Main thing is for a really good fit for the vac line.
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Re: Gauge of pipe from carb to vacuum advance

Post by Aidan »

I carry the hard and soft hose in stock in a range of colours for the difflocks on the syncro, the soft is blue at the moment, I think I have run out of red

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