Air filter replacment

[zeds27]

I'm building a kit car using a 1490cc twin carb (Dellorto DRLA carbs) Alfasud Sprint engine and gearbox. The original air filter won't fit under the bodywork so I would like to replace it with individual air filters on each carb.
1) Do I need to fit rampipes for the filter to fit over or can I simply fit the filter onto the base plate?
2) What happens to the carburettor vacuum balance pipe. Do I need to have the carbs tuned individually

Or am I miising something?

Many thanks

Kevin

[Greek]

You can use the individual filters without rampipes. Using rampipes you just change the range of profit on the rpm that you want or in other words , in favor of torque or rpms. Of course if you have also changed your venturi inside the carbs or you have changed needles to bigger ones it is advisable to go for rampipes to compensate the need for more air.

[markp2]

Hi Zeds, what kit car are you building. I have done a couple of Minaris in recent years so know the issues.
Firstly, you can blank off the 4 thin pipes going from each intake to the air filter housing. You will need to sort out some sort of engine breather pipe though ( I used to have a pipe leading to a plastic milk bottle hidden out of view!)
The carbs will work better with ram pipes than without. For road use I would get the longest you can fit under your bonnet allowing at least 25mm clear space above them. Sock filters or K+N type with a base plate work equally well.
I (others may disagree) would also go up one size on the air corrector jet to compensate for the additional airflow through the carb. This will help prevent flatspots in the pickup. Depending on how much air flow you actually achieve when the car is moving, you may need to increase main jet size as well.
Cheers,
Mark

[zeds27]

Hi Mark
I'm building (and have been for the past 8 years due to various reasons) A Martyni 23 which is a replica of a Lotus 23. You can't buy this kit anymore (which is part of my problem) . See Martyni23 Sportscars Homepage.
I'm the customer test driving the car.
The engine breather pipe - is this the pipe going to the oil filller? It was mainly the 2 larger tubes going to the top of the old carb intakes that I was concerned about, but you seem to be saying that I can do away with all of the 4 four small tubes as well and just have one air breather. Is this correct? I'm a bit thick so what do the 4 small tubes do then?
Thanks for your interest
Kevin

[melv]

i think maybe a picture of someones carbs may help you.
i have k&n on so will try get a pic for you so you can see were the little pipes go.

[melv]

will post pics just as soon as i can figure out how to use new updated photobucket

[melv]

http://i588.photobucket.com/albums/ss324/melv/001.jpg
http://i588.photobucket.com/albums/ss324/melv/002-1.jpg

hope this helps .

[Spacenut]

Hi Kevin - interesting machine you have there. I have never heard of a Martyni 23 before, and judging by the chassis pictures on the website it is no relation to the Noble/Auriga/Mamba replica. I have got a 1.5 Ti in my Nova kit car (which actually uses the Noble 23 suspension wishbones and rear uprights, as I wasn't happy with the VW Beetle underpinnings). My engine is bone stock, but I have changed the air filter box for a pair of K&Ns. The leaflet that came with the filters suggested upping the air corrector jet, as Mark says, but I haven't done that on my engine, nor have I fitted ram pipes. I think it runs OK, although there may be a slight flat spot - its difficult to tell. I left all of the breather hoses in place - the two 10mm pipes that went to the carburettor elbow castings I have attached to the rear of each filter (there is a very expensive optional extra K&N part that does this, but I just used ty-wraps), and left all of the smallbore scavange pipes in place. With the K&Ns sucking in air from all around their perimeter, the 10mm pipes are essentially just acting as vents - there is no manifold depression to scavange the fumes from the crankcase. This just leaves the smallbore pipework, which connects to the inlet manifolds below the carbs.

Eventually I will get around to moulding some airboxes for the filters, at that point I will integrate the stub pipes for the crankcase ventilation and the large bore squeegy pipe from the upper body intakes, but I won't be doing any of that until my new engine is in place.

I guess you will be running without the brake servo, I found that the hex-head blanking plugs in the carburettor elbows are interchangeable with the servo take-off stub in the RH inlet manifold. Swapping them over makes for a neater engine bay, and no vacuum leaks

Lauren

[markp2]

Zeds,
The simplest was is to get rid of all these pipes. Fit a pipe to the metal stub just below the oil filler cap and lead into some sort of collection vessel (1 litre size would be about right). This will catch any oil spray and water vapour coming out of the crankcase. On the standard setup this is fed into the carbs and is burnt - to reduce emissions, I expect.
As long as you don't have to register your kit as a 'new' car, you should be able to use the catch tank system. If your SVA tester is picky (many are!), you can get a proper catch tank with a little air filter on it from Demon Tweeks.
Cheers,
Mark

[zeds27]

Thanks to everyone for their patience in explaining this to me

Regards

Kevin

[zeds27]

Final question
Where do I take the vacuum ignition advance from?

[Spacenut]

There is a small stub pipe on the left hand carburettor (looking forward), about half-way up the body. Don't confuse it with the two vacuum guage stubs near the base of the carbs - they are for connecting a set of four vacuum guages when setting up the airflow.

Lauren