confused... servo vacuum feed on webber 34ict?

'the vacuum hose that's hanging around at the back of the engine bay somewhere... 'I

Brilliant, I think you may have inadvertently solved a puzzle I'd been looking at in the van for a year now. There's a blocked end of a pipe I couldn't figure out what it was for, I'm going to check that out first thing.

 

Think you have the gist and it sounds to me like you have the pipe fitted. For info, as someone mentioned it, type 4 engined buses had servos as standard. It wasn't standard on type 1 engined buses in the uk but was an option from new so some have one, most dont.

My 1700 had a non operating servo for years and although the brakes were ok i had a right leg like Thor! Fitted a replacement servo when i managed to find one and it was a revelation. When you get it fixed dont test drive it without your seatbelt or you will be scraping yourself off the windscreen!

 

Mine is a US imported '71, which I think, happy to be corrected, was the first to have them.

Thanks for all the help though everyone, I'll post how I get on.

 

Ok, another quick question.

I have found the pipe running out of the servo. I'm assuming the other short one that's dangling and open to air is also correct, I can't recall its name or purpose.

With the end that's in my engine bay, it has a connector that to me looks like a vac one, if I run the engine and press the brake should I feel a sick if I stick my finger over the end?

Or indeed is this an utterly stupid thing and I will I be sucked into the engine? ; )

 

You just tee into the balance pipe that gos from one carb to the other

 

I thought you had to go into the manifold?

The balance pipe I have, that feeds into my svda, is from the carbs themselves and I believe the feed is above the butterflies. If I can take a feed off that too it would make life very easy.

 

You are correct. the balance pipe should be between the two manifolds. The two small brass vac outlets on the carbs are above the butterflies and are no good for a balance pipe or vac signal for the servo. most people who have ICT's fitted have a balance pipe fitted between the manifolds. It helps significantly in getting a smooth idle. Both manifolds need a union fitted and a tube of about 10-12mm ID fitted between them. If you have this you can just T into it for your servo.

 

A picture of your set up would advise people and allow them to give so e better informed advice as at the moment were all speculating. You may not have a balance pipe for example, your vac connection might be a tank breather etc. Etc.

For clarity the internal diameter of the vac take off to the servo and therfore the vavuum pipe will be around 8mm or larger so if your not looking at a pipe of around 15mm or larger external diameter, and it most likely will be larger, then your not looking at a pipe that bug enough to provide sufficient vacuum for your servo.

 

Where is this pipe (hose?) dangling from? The servo needs vacuum from the manifold and it also has a breather that should be in a dry location. And there needs to be a non-return valve at or near the connection at the manifold.

Don’t do this^.

The pipe from the carbs is not a balance pipe; the distributor will work connected to one carb but to both won’t do any harm; it won’t get twice the vacuum.

When you don’t know what things are or where they are or what they do pics would help us help you.

 

i have now crawled and looked.

the breather is there.

the pipe with the barbed end in the engine bay, doing nothing, is the vac pipe off the servo.

the manifolds do not have, and have not been modified, to have either a balance pipe or a feed to the servo.

my svda feeds from the two brass pipes at the bottom of the carb.

it now looks like i need to remove my left (as i look) carb, again as i only had it off two weeks ago to change the jetting, and see if i can remove the empi manifold then find someone to drill and tap it for me.

i find it incredible that a VW specialist who did this in 2009 would have fitted these carbs and not done the job correctly, incorrectly jetted carbs is one thing but when braking is concerned its really bad imho. but they are no longer in business so there you go.

 

Maybe, as in my case, the servo pipe was already disconnected because the servo was u/s. Have you had a look at the servo yet to see what condition it's in?

 

Makes you wonder why they're no longer in business

Buy a 1/4" NPT barb and NPT tap off fleabay and do it youself. Easy enough. I'm surprised you can stop your van at all with a servo master cylinder and unconnected servo

 

I did wonder that, so I'm expecting to hook it up and then have to replace it, but then it's also an mot fail, albeit one that not been picked up in the two or three it's had since, so why do that?

That's why I was wondering if there was a way to see if it's trying to pull any air just from putting my finger on the end of the pipe, you never know until you ask.

The condition does look ok, and after all it's not been used for 8 years. : )

Great learning experience though, I do appreciate all the feedback.

 

It's the engine that does the sucking, not the servo

 

http://www.ebay.co.uk/itm/172587625292?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

 

thanks snotty, i do have all my dad's old taps and dies but thats really useful to know what one to use.

one question, is it something like this i need to buy?

https://www.hoseshop.net/brass-hose-tail-14-bspt-male-x-14-hose?gclid=CMffk9-K7dMCFVdAGwodB08HZA

 

Yep, something like that, or maybe a right-angled one. You could use good old British BSPT - you need a tapered thread so the fitting seals - but I used US NPT threads (tend to be common on this kind of stuff). Depends what taps your Dad's got

http://www.ebay.co.uk/itm/BRASS-HOS...NPT-MALE-BRASS-HOSETAIL-9-02093-/231403947772

Don't be deceived by the "1/4" - 1/4" NPT actually fits a pipe ID of about 1/2"/13mm, which is a good size for the servo.

Have a go - it's easy. Just make sure you drill the right hole size for the tap.

 

trying to get my head around threads with google, and i think i see what you mean about tapered or not.

if i buy the tap you posted earlier so i know i have the right part, am i correct this is the part i then need (its the only right angle 1/4 npt hosetail i can find)?

http://www.carbuildersolutions.com/uk/90-degree-brass-8mm-hosetail-14-npt

 

I'd check first what the inside diameter of your existing vacuum hose is, so you get the right sized hosetail.

NPT will be fine, or BSPT (British Standard Pipe Tapered), if your Dad's got a tap. The taps cut a thread that has the threads on a taper, rather than being straight-sided. This helps it seal as you screw it in.

 

http://www.advancedfluidsolutions.c...ose-joiners-equal--reducing-menders-115-c.asp