Twin ICT Balance Pipe?

[georgeyv]

Hi all -

Finally getting round to fitting my Weber ICT carbs in the next couple of days - just making sure I've got all the correct bits but one thing I'm unsure on (even more unsure after reading so much divided opinion) is the balance pipe between the carbs.

I've got CB manifolds with 1/8 bsp threads tapped in. I have no fittings yet so will buy those. Who has these fitted and what size tails/hose have you used? How is it routed? Any help greatly appreciated.

Thanks!

 

[1961bluebug]

Use largest hose allowed by fittings, I use upto 1/2" hose on Type 3 Solexes and Kadrons, route behind cooling shroud but keep the hose from obstructing thermostat linkage.

 

[rlepecha]

I'm using 8mm hose with 1/8 npt barbs.

Think there's some suggestions that a balance pipe too big, making the carbs easier to tune, also results in power loss as the carbs can be well out of balance but appear ok due to the large flow area in the pipe which allows significant air(and potentially fuel) flow between the carbs.
8mm seems to work fine on my engine with twin ICT's.
I set the balance using a small ball bearing in some clear tube on attached to the two barbs.
Gravity sets the centre point in a loop, mark that, start the engine and adjust carbs/linkage till bearing centres over the mark made earlier, perfect balance without the need for an expensive snail gauge.



Sent from my Swift 2 using Tapatalk

 

[StuF]

Just for information and balance of opinion - my twin 34 ict carb setup had a balance pipe fitted, it was 8mm and ran around the back of the fan housing.

Took the bus to get rolling road tuned at an aircooled specialist in Lincolnshire and he advised me to remove the pipe and blank the takeoffs due to the size of the carbs.

He demonstrated there was no performance loss removing the pipe with a rolling road session before and after - figures were identical.

His explanation was that the 34icts don't draw enough air compared to large twin carb setups like 44's/46's so I was just introducing another area where air leaks could appear.

Had the rolling road session a year ago and the carbs are still perfectly in balance and the bus is running brilliantly.
Might be worth running without a balance pipe and see how you get on

Snail gauges aren't that expensive and are a useful tool even if its just for checking the carbs periodically

http://www.ebay.co.uk/itm/Dellorto-Weber-genuine-synchrometer-carb-balancer-made-in-Germany-not-China-/290682796527

 

[georgeyv]

Cheers gents - it's kind of as I suspected really - there isn't a general consensus!

I'm going to fit the barbs on the manfolds and then blank them off, that way if I have issues running without a balance I can fit one without much stress.

I sold my snail gauge before I bought the bus and after I sold my Mk1 golf on twin carbs - annoyed that I did now!

 

[gvee]

I've got a snail gauge if you need to borrow it mate - you know where I am!

Your set up is very similar to mine, and to be a bit contradictory, a balance pipe matters... but that's because you and I are running a brake servo (which I don't imagine Stu's '70 does)!

I have vacuum hoses from one car to a t-piece, running behind the fanshroud. This then goes to a 1-way valve and off down the body to the servo.

 

[atafonso]

Just for information and balance of opinion - my twin 34 ict carb setup had a balance pipe fitted, it was 8mm and ran around the back of the fan housing.

Took the bus to get rolling road tuned at an aircooled specialist in Lincolnshire and he advised me to remove the pipe and blank the takeoffs due to the size of the carbs.

He demonstrated there was no performance loss removing the pipe with a rolling road session before and after - figures were identical.

His explanation was that the 34icts don't draw enough air compared to large twin carb setups like 44's/46's so I was just introducing another area where air leaks could appear.

Had the rolling road session a year ago and the carbs are still perfectly in balance and the bus is running brilliantly.
Might be worth running without a balance pipe and see how you get on

Snail gauges aren't that expensive and are a useful tool even if its just for checking the carbs periodically

http://www.ebay.co.uk/itm/Dellorto-Weber-genuine-synchrometer-carb-balancer-made-in-Germany-not-China-/290682796527

I agree it can be made to work very well without the pipe, but FOR ME, with the pipe it's easier to tune and also in my experience the engine runs and idles smoother. Try to block the pipe while the engine is running and you will see the engine will start shaking slightly.
Just a reminder, VW used the pipe in all dual carb variants of the aircooled engine, so it tells something IMHO.
Abel

 

[K@rlos]

They can be made to work without the pipe but when installing dual single throat carburetors such as Weber ICT's or Kardons they operate a lot smoother at slow engine speeds when a balance tube is installed between the manifolds. The balance tube allows equalization of pressures and provides a balancing effect during idle and mid range RPM.

 

[Simshaz]

I bought the CB Performance kit as my 34's were going on a type 4. Came with the bits for the balance pipe but tickover and low revs are great