Air filter pipes

[brindy123]

Can ayone tell me what the 2 pipes that come from the air filter do? one goes back round the a pipe going to the carb and ones re connects down the air inlet pipe??

The reason i ask is that i am thinking off getting a custom K&N oval air filter to sit right on top and wondered if the pipes can just be left unconected??

hopefully someone can help,

[MacColl]

I think you mean the vac (vacuum) pipes that make a flap on the air box close in cold weather directing warm air from the exhaust manifold to the carb (carburettor). This helps prevent carb freezing.

The one at the back of the carb simply would need to be blocked off with something like a screw or bolt in the rubber tube to run that type of filter.

However there is a view that running this type of air filter is less efficient. In winter and in certain conditions not advisable because you need that controlled optional heat to prevent carb freezing. Also heard the view that the K+N filter is drawing poor quality air round the warm engine area. I am not a fan of how the standard air box looks and have thought about other options like an elbow part off a Golf that allows a choice of filter on it's end.

I'm not sure how well the standard Pierburg Carb would behave with this filter either because of it's complexity? and for that matter the Weber Carb replacement. No doubt someone has used one on here.

I'll add that I am only going by other opinions/views I've read and from other peoples experience.

[Nate]

as i've said before, carb icing isn't a huge problem. it's not like these things are 6 litre engines that are vapourising gallons of fuel every minute. but yes, in an ideal world, you want the air going in to be as cold as possible, to make it as dense as possible. i ran my mk2 with an elbow off a mk3 golf 1.4 single point injection, going down to a cone style filter (i can supply these unbranded for £15+post if anyone interested, still got half a dozen in the shed) behind the o/s headlight. in an ideal world, this should be shielded from the engine to stop the air getting warmed, and should also have some way of making the air less turbulent, as it is easier for the engine to suck in still air. if you don't believe me, stick your head out the window while you're doing 70 and try and breathe normally! that said, it worked fine. didn't make the car any quicker, but definately didn't make it slower either

[dozzum]

The only other thing to watch out for when changing the standard air filter is that the it provides the carb with some support onto the rocker cover if i remember correctly. Without that the carb is merely bolted into the rubber gasket that is in turn bolted into the manifold.

So if your rubber gasket it a bit old as mine is then it may snap off if the carb starts swaying around.

I couldnt work out why the car kept stalling round corners until one day the carb fell right over.