Tuning The Idle Mixture Screws On 45 Dcoe's

[wardy18 33 1 Cars]

Ok so how the heck do you do it?!?!

 

I have now balanced the carbs but now need to try and set the Idle Mixture Screw for the Carbs mixture

 

My info sheet says to screw in one screw clockwise until the engine tone or tachometer (which i dont have so im listening for the engine tone) to fluctuate, you then have to unscrew the screw anticlockwise until the revs are at a steady idle, all 4 screws shouldnt be more than 1/4 turn different to each other

 

well blow me i cant work it out, ive set every screw at exactly 1 whole turn from completely screwed in

 

then ive screwed one in clockwise and the engine tone lowers, u then turn it back out and the engine tone increases, so what the flippin heck am i meant to be listening for?! the revs just go up and down until the car pretty much stalls

 

HELP PLEASE........

 

how have u done yours?!?!

[wardy18 33 1 Cars]

ok in reading a Weber manual, am i right in reading that u need to keep turning each screw anti clockwise until the engines rpm doesnt climb anymore and then screw it back in clockwise to the point at which the engines rpm starts to die. do this one at a time and adjust the rpm with the throttle adjusting screw as you go!?

 

will the rpm actually stop climbing when you get to a certain point when turning a screw anti clockwise?!

[skinner2k3 3]

Everything I read tends to suggest a different starting point for the idle screws. One thing worth doing first is checking the idle screw taper is in good condition before you start.

 

I am currently looking through the Des Hammil Speedpro weber manual and it seems the best so far, deffinately worth a look.

 

I will double check tonight what starting point it suggests but 1 1/2 turns out from lightly seated rings a bell. Then turn all four a 1/4 turn in the same direction. Allow 10 seconds for the engine to settle and note if the RPM increased or decreased. If it goes down try the other way and keep readjusting the idle via the throttle stop to about 1000rpm. You want a position whereby a 1/4 turn of idle screws either way lowers the idle.

 

Once you have it as good as pos re syncronise the carbs. Then adjust the idle screws one at a time for highest revs. If one of the screws seems to make no difference no matter how you adjust it then there is probably a blockage in that side of the carb somewhere.

 

The book also mentions a max/min number of turns of the idle screws before a change of idle jets are required. Again I will check later for you.

[wardy18 33 1 Cars]

ok mate thanx, i just find it very hard to get accurte results trying to hear for slight engine tone increase decrease, suppose i will jus need to keep trying and see how i go, i think ive got it pretty good at the moment but yeh ive done it how you said it above so at least i know the procedure now

thanx for the info mate

[skinner2k3 3]

No worries, have the book on me now and I did remember it pretty much correctly, except the starting point should be 1&1/4.

 

It says that Webers normally need a minimum of 3/4 to 7/8 of a turn out from lightly seated and a maximum of 1&1/2 turns. Any less than 1/2 out and the idle jets are likely to be too large, any more than 2 full turns and the idle jets are too small.

[wardy18 33 1 Cars]

excellent well i think mine at the moment are about 1 1/4 to 1 1/2 but ill have a go at tuning them at my next event again, its a quite and easy task now i know what to do so its just a matter of trying to fine tune them

 

im going to buy a AEM Wideband O2 Sensor Guage so i can also use this to get accurate settings with the idle jets

[skinner2k3 3]

I have been looking at them recently too, am trying to figure out if any bosch wideband sensor will do the trick. I think the post 2000 golf 1.8 GTI had a wideband lambda. Our electronics guys at work dont see a problem in writing some software to convert 0-5v into a digital AFR value and displaying it on a little LCD. We shall see!

[wardy18 33 1 Cars]

cool, its great if you have the expertise to hand around you, good luck, let me know how u get on