Carb tweaking after installing K&N filter?

My 1.3 isnt running quite as well as it was when i had a standard filter on, and ive only just realised that it might be running a little bit too lean due to the increase in air flow? I dont really get on with carb tuning so if anyone knows how much roughly the mixture would need tweaking? but im guessing it will need completely re-doing! Cheers,
Matt

Try the mixture screw…

Adjust it a quarter of a turn at a time… after the engine is warmed up and listen for changes in rpm and spitting and popping.

Out to richen, in to lean.

If the carb is popping /spitting back out the intake then it's too lean.

Get some carb cleaner sprayed in there too.

Thanks mogs, it had some work done last august and the carb was set up perfectly so its only a slight difference I've noticed. So I might try a slight increase of mixture and see what difference it makes

I just can never tell when I've got it at the right point when I'm setting it up!

I brought a emisions tester like this but with an analogue gauge (older version) I tried setting the car up by ear and driving but could not get it right, after setting it up by the book the cars drives so much better, well worth the money. I picked mine up for £35 from ebay (2nd hand)

This one is starting at £20….
http://www.ebay.co.uk/itm/Gunson-Gas-Tester-/261363502595?pt=UK_Diagnostic_Tools_Equipment&hash=item3cda7a8e03

Is that a reliable way of setting it up? I've seen in the Haynes that that can be done so might be worth giving it a go, thanks

I have one of those and a 4 way airflowmeter jubby and a gunsons colour tune, I've used them all to tune and balance my carbs but now I get very good results by doing it by ear, it's really not that hard. I've done a few including twin carbs on mk1s and beetles and everyone has been happy with improvements.

If you're worried about putting it out of whack you just count the turns your screws are set to at the moment (screw your mixture and idle screws all the way in and counting the turns as you go). So you know where you were if you want to go back.

The way I do it is: You want to get the idling engine speed fastest by adjusting the mixture screw (usually out) until adjusting it out makes the engine speed start to drop or there is no increase in speed (a half or a quarter a turn at a time and waiting to listen / notice engine rocking and exhaust note between adjustments). It should get smoother and the exhaust note will pulse nicely (or evenly if you've got more than one carb). Then you trim your idle adjust screw to drop the engine speed. And then repeat… adjusting the mixture screw and trimming the idle down. The aim is to get the engine running faster with the mixture screw, until a turn in either direction will make the engine speed start to drop. Then to finish, half a turn out and set your idle to where you want it. Voila!

I did teach myself by reading Dellorto manuals and stuff so feel free to call BS on any of the above, but it works for me.

Ive got the colour tone thing but didn't really get on with that either  

 
That info on the tuning sounds really useful thanks! I've read up on it before but thats made things a bit clearer, ill try nd adjust things this weekend and report back   thanks

set the timing first,check the points gap and the points are in good nick,make sure the plugs and leads are in good order,then go to your local mot station they can set it in 5 mins on the mot machine
Bert

Yeah the colourtune is a load of balls to be honest. Cool though.

Like Bert said, check all the usual suspects before attempting the black voodoo magic on the carbs. 

I've wasted days trying to retune my carbs when it turned out to be a bad earth. You'll notice you can be what seems pretty far out with carb adjustments and it'll be fine. I've learnt not to suspect carbs when something goes out of whack. Usually an air leak at the manifold or carb seat/ exhaust leak will give similar symptoms to bad running carbs.

If the K&N filter has done away with the existing air filter box and the warm air gubbins that could well be your problem. Was prob OK in August but now its cold and wet you could be suffering from carb icing (doesn't have to be below freezing outside, just damp).

If you still have all the old parts but them back and see if that cures it. What use is the extra .00005hp from the K&N if it makes your car not work?

well I think my issues with the carb tuning before was when my head gasket had gone which is why it went to a garage who sorted everything out.

The filter ive put on is just a replacement to the ring shaped one so all the intake plastics and warm air feeds are still in place, well Im not fussed about the hp because your right it makes very little difference its more that the k&n can be cleaned when it gets soaked in oil from the crankcase breather which in the long run will save me money replacing standard air filters