32dis Jetting

[Philclubman]

Hi, im having trouble with my carb, my wideband shows a very rich mixture between idle and 2000 rpm when there is an amount of throttle applied. It idles fine at 14.5:1 and above this cruises at 14:1, on boost it is at 12:1 across the revs. This is really annoying me now as I know it is very rich where I spend most of the time driving, as I use the car every day. When setting off in first it jumps straght to 10:1 and hangs around there sometimes coming down to 11:1. so If im driving gently its always running rich.

My carb is jetted as follows
Main 117.5
Air corrector 1mm
1st stage enrichment 1mm (removable jet)
2nd stage jet drilled to 1.3mm
25mm venturi
.45mm idle jet
2mm needle valve, though I have tried a 1.7mm with no difference.

Ive read about running a 0.6mm 1st stage jet? would this weaken the mixture at this point in the revs, I thought it only opened when manifold vacuum became zero.

Im woundering if my 1st stage jet is not working properly, maybe its not recieving the vacuum signal to keep it shut.

I have tried alsorts, the carb has been overhauled aswell.

Ive looked down the carb when its running, theres no obvious signs of fuel dripping from anywhere.

Any help is much appreciated, cheers guys

[Philclubman]

Right ive just had it all apart and blown through every last little hole with compressed air, cant find any blockages or obvious problems, has anyone tried the 0.6mm 1st jet? just wounderd what affect it has to the mixture,

p.s. im running 20 psi with a VNT, other than the richness between idle and 2000rpm Ive no other problems

Cheers for any help

[Adey aka Ewok]

not tried going smaller to be honest tho i have heard of shimming the 1st stage spring so it comes in slightly later? but if thats what your cars asking for try it? if youve got the lambda and its not on load im sure itll be fine to try it:agree: 20psi carb top or manifold?

[Philclubman]

Thanks, that sounds worth trying thanks, i'll give that a whirl tomorrow, yes its 20psi manifold mate

[Philclubman]

Having done some more reading, really I need to weaken the first stage spring, or as I think I will try, reduce the 1st stage jet, I will post my results lol

[Matt Cole]

Yes you can shim or adjust the first stage spring. Have you drilled out the aluminium blanking ball in the housing for adjstment??

[Adey aka Ewok]

Yes you can shim or adjust the first stage spring. Have you drilled out the aluminium blanking ball in the housing for adjstment??

forgot about that, theres an adjustment screw behind it isnt there?

[Philclubman]

Thats the second stage lads, which opens when there is boost

the first stage opens as maniofld pressure reaches atmoshperic, when at low load, idling etc, the manifold vacuum pulls the first stage shut, as the vacuum goes when throttle opened the springs opens it letting fuel pass through.

Ive tried reducing the spring pressure and also now reduced the first stage jet to 0.7mm but i still get a massively rich mixture, it is better but still hangs around 10:1 with light throttle, i.e when pulling away

Id it possible the float level is too high, is there a measurement or way to check?

[michael tierney]

if ur accellerator jet is leaking(beside the emulsion tube) when it is pumped it may do this other wise check the size of ur idle jet to make sure its 0.45mm....
when idling nice and lean,as soon as u press throttle sightly it will richen with the acc.pump shot and the fact that the engine is drawing more on the whole progression slot!as the throttle opens more it leans slightly until u start drawing main jet,so u dont actually come on to main jet until about 2000rpm on light accelleration.

[Philclubman]

yeah idle jet checked, its is .45 lol ive tried two, no luck as yet, thanks for the help

[Mart]

What's the accelerator pump (lever) travel set to?

[Philclubman]

5mm as per the book mate

[Brigsy]

I have the same problem now i have sorted the idle on my carb. Afr's drop into the 10s, even 9s at low load/rpm driving. As soon as the engine is over 2k it sorts itself out.

Im thinking of adjusting the lever travel a little to see if it will lean it off as i did adjust it when rebuilding my carb.

[Mart]

5mm as per the book mate

Might be worth adjusting the rod so that there isn't as much rod travel as per the amount of pedal movement; ie, to give a slower/longer flow of fuel from the pump jet.

[Philclubman]

Right ive gone back to 1.7mm needle jet as although it sealed most of the time, I think it kept having little moments of overfilling the bowl. With the 0.7mm first stage and softened spring im gettin better afr's of around 12.5 to 13:1 while at low throttle.

Any one know where to get a proper 2mm needle valve or any advice on float level and using two copper washers t reduce it?