weber twin 45's high idle problem!

[vibrating_Cake]

Right ive got a 2.0 zetec on twin 45 weber carbs, all jetted correctly from the previous owner and RR-ded at 170bhp running fine.

but ive just been tinkering as the idle was rough as hell, and noticed when i lifted the carbs up the engine picked up speed.

 

 

so, i got my spanner out and tightened up the misab plates and rubbers, the idle raised, so i screwed down the idle a bit more.

i continued doing this until the engine rpm didnt increase anymore.

 

 

now i have the problem that the idle screws are at the top and the engine is running at ~ 3krpm on idle with no more ajustment on the idle screws. the engine is running 100x better than it did before,

but how do i reduce the idle further????

[BIG G]

balance um up

[vibrating_Cake]

balance um up

 

what does balancing em up actually do??

as in wtf changes to make them balance up, air bleeds or something?

[Lukey48screamer]

Surely you dont mean its idleing at 3000rpm do you? You'll have an empty tank in no time!

 

Balancing them I believe is getting the mix between air intake and fuel just right on both carbs whilst adjusting them to let in the same amount of air/fuel mix on both individual carbs..thus getting the correct idle.

 

have you checked to see if the throttle cable/linkage is backed off properly? sounds like your movement of the carbs is effectivley accelerating/pulling the throttle cable if you know what I mean..

[vibrating_Cake]

 

the rod in the middle????

 

 

 

the linkage is touching the body of the carb, as you can see from the bottom shot theres no more ajustment left in the idle at all

[Lukey48screamer]

Do you have a fuel pressure regulator? it may help if you have a tweak with that.. I would imagine that because yr carbs are now effectivley closer to the head the time/distance for the air+fuel mix to actually get into yr engine has shortened therefore more fuel passing in faster than it did before so now a faster idle... maybe

 

 

If they were balanced+running nicely before I wouldnt touch the carbs too much, sounds like you just simply need to back off the total amount of fuel coming in... Maybe

[vibrating_Cake]

Do you have a fuel pressure regulator? it may help if you have a tweak with that.. I would imagine that because yr carbs are now effectivley closer to the head the time/distance for the air+fuel mix to actually get into yr engine has shortened therefore more fuel passing in faster than it did before so now a faster idle... maybe

 

 

If they were balanced+running nicely before I wouldnt touch the carbs too much, sounds like you just simply need to back off the total amount of fuel coming in... Maybe

 

its at 3psi atm but i dont know how to ajust the filter king regulators (cause its second hand without any instructions lol)

buttt... the needle valves in the top of the carbs would stop flow into the float chambers when the float is at its peak anyway, so i doubt that would help =) lol

[Lukey48screamer]

Bit stumped then

But pop bits of this thread into the WPE section and wayne will have all the ideas, Im pretty sure he checks the forum every evening.

He'll def know - he's the man

[vibrating_Cake]

cool thanx, just posted it up in there

[zetecmk2]

you have an air leak from the misab's, the carbs arn't supposed to be bolted up tight as vibration causes the fuel to foam in the bowl, put them back as they was and don't lift them up!!

[caprinerd]

er it might sound a bit stupid but have you tried slakening the throttle cable back m8 just a thought on the top of my head

[vibrating_Cake]

you have an air leak from the misab's, the carbs arn't supposed to be bolted up tight as vibration causes the fuel to foam in the bowl, put them back as they was and don't lift them up!!

 

yeh i do have an air leak from the misabs... but when i seal the air leak the engine idles at 3krpm....

when i slacken them off so theres no air leak the car hisses from the misabs and has a very rough idle that shakes the car nvm the carbs!

ive got some more misab's in the post but i need to know how to lower the idle more because itll idle at 3krpm on the new (sealed) misabs!

 

throttle cable removed it does the same thing that was the second thing i tried =)

[zetecmk2]

manifold to head airleak? spray wd40 around the mating surfaces, misabs and butterfly spindles, if you spray over a leak the rpm will rise failing that....rolling road!!

[vibrating_Cake]

manifold to head airleak? spray wd40 around the mating surfaces, misabs and butterfly spindles, if you spray over a leak the rpm will rise failing that....rolling road!!

 

manifold to head was loose too lol!

well until i get my new misabs through itll have to do for now, one carb is angled upwards and the other is relativley level.

so i ajusted the centre screw between the two carbs until both fingers on the underside of the idle screws touched the bases at the same time.

this brought the idle down to 900rpm on idle on fully unscrewed which is still high seeing as though theres no more leway.

 

but it worked. hope i can get it sorted when the new misabs are in place .

then RRoad to get it running properly after that =)

[vibrating_Cake]

oh and should i be using locking nuts on the spring cups as opposed to normal nuts as they sit at such a low torque?

[flyingbanana]

if you want info on complete strip down and rebuild and setting up PM me your email address and ill send the pdf too you

[vibrating_Cake]

if you want info on complete strip down and rebuild and setting up PM me your email address and ill send the pdf too you

 

nah its alright, i know how and everything, the tuning up i'd always leave to a professional anyway so im gonna try get somewhere that can map my ignition while they do the old carbies get it done propper once n never go back!

 

thanx for the offer though

[zetecmk2]

yeah, use nylocks

[vibrating_Cake]

yeah, use nylocks

 

i thought they looked wrong!!

when its off ill get some sorted =)