AFR's Carb set up help

[Wallace]

Hi all,

Just been for a spin in the 5 and its not fueling correctly at all - any help is greatly appreciated

I'm using an AEM Gauge, the engine is standard and i've turned the boost right down, as the engines got barely 30miles on it since rebuild!

The carb is standard venturi as far as i can tell...............i had measured it with a vernier but that was ages ago.....so a pointer here would be very helpful

Carb Spec:

A/C Jet=100 - Main Jet=120 - 2nd/Enrichment Jet?=125

I've set the idle which does fluctuate between: 13.6 up to 14.7, but does appear to remain around 13.9 up to 14.2.......and this has been set whilst letting the car warm up, then turned off etc to see if it remains stable, which it kinda does!.................

But after the car has been run upto temperature,fans kicked in a couple times and more importantly the car be driven!!!! once i stop and leave it to tick over (around 1000rpm) I'm back to afr's of around 12.1 on idle?

Also, general driving - up to around 3000rpm i hit a flat 10.0 and only moves once i come off throttle completely and it will read around 12.1 again

I have checked for air leaks with carb cleaner and nothing changes!

Soooooo what i'm wondering is:

(1) Whats people opinions on the idle AFR's? - Adjust it again once its been used i assume?

(2) When we talk of 'Group A' Carbs - where should i be measuring, I know venturi but a little more info please? (i obviously wanna rule this out!)

(3) To get this reading of 10.0 adjusted or at least moving one way or another!! - Can you offer me some starting points please?

[casper]

Hi,my carb is set up for 1bar of boost,just as a test I put a 1.00mm a/c in from a 1.20mm and it cocked the fueling up big time,super rich and not just at high boost,was surprised at just how much of a difference it made

[Wallace]

Hi,my carb is set up for 1bar of boost,just as a test I put a 1.00mm a/c in from a 1.20mm and it cocked the fueling up big time,super rich and not just at high boost,was surprised at just how much of a difference it made

Cheers

Been 1 of my considerations as the original carb (which i assume to be factory standard) has a 120 in it.......

I've thought also, looking at your previous thread, that accerlater pump may be adjusted incorrectly too....

The joys

[casper]

Think the a/c was 1.25mm as standard.I no every engine is different but your jets would fuel 20psi on my car.

[Wallace]

20psi

I'm gonna have a crack at it again tmrw- can anyone shed some light on the accelerator pump adjustment?

[Dave Reed]

20psi

I'm gonna have a crack at it again tmrw- can anyone shed some light on the accelerator pump adjustment?

Use a 5mm drill bit to set the acc pump.

[James5]

20psi

I'm gonna have a crack at it again tmrw- can anyone shed some light on the accelerator pump adjustment?

Smooth end of 5mm drill bit let it rest against the slot in the carb and let throttle butterfly rest against it then adjsut the bolt / spring so that it is pushing just pushing the pump jet in fully at this point

[casper]

What if the acc jet is putting too much fuel in even after setting with a 5mm drill bit?Is it just a case of shortening the stroke on the pump arm?

[Wallace]

Use a 5mm drill bit to set the acc pump.

Errrrrrrr

[Wallace]

Smooth end of 5mm drill bit let it rest against the slot in the carb and let throttle butterfly rest against it then adjsut the bolt / spring so that it is pushing just pushing the pump jet in fully at this point

Cheers James

I kinda get the idea..............this will not be helping either way as i've never set it up properly before now

[fishead]

if ive read this wrong i apologise, but just in case



the boost enrichment is a fixed bush, not a jet. if the removeable jet in your enrichment block is a 125 a/c type jet. that'll give you your 10s put it back to 100

[michael tierney]

check the carb at idle and part open throttle that there is no fuel dripping from the aux venturi!

[Wallace]

if ive read this wrong i apologise, but just in case



the boost enrichment is a fixed bush, not a jet. if the removeable jet in your enrichment block is a 125 a/c type jet. that'll give you your 10s put it back to 100

Cheers Tony - I'll do this tmrw

It wont be you reading it wrong mate, its gonna be me being a numpty

all gotta learn

[Wallace]

check the carb at idle and part open throttle that there is no fuel dripping from the aux venturi!

I'm sorry Michael but can you explain that in idiots terms - you've just enlightened me that theres even an 'aux venturi'

Thank you

[casper]

Hi Wallace, hope you don't think I'm hijacking your thread but this may help us both.Today I noticed the jet of fuel coming from the acc jet was almost going straight onto the throttle plate,don't think this is correct,thought it was supposed to hit the wall or center part first,could someone advise please.

[Wallace]

Hi Wallace, hope you don't think I'm hijacking your thread but this may help us both.Today I noticed the jet of fuel coming from the acc jet was almost going straight onto the throttle plate,don't think this is correct,thought it was supposed to hit the wall or center part first,could someone advise please.

Crack on mate,its all learning

[michael tierney]

the auxiliary venturi is where the discharge nozzle is, right in the middle of the main venturi! when u open it up"u,ll see the fuel mixture coming out! it should,nt drip at idle or just off idle....if it does its more than likely ur needle and jet...dirty or worn! with regards to the acc.pump jet i think squirting towards the throttle plate is correct!

[GT Josh]

Squirting is correct mate. Usually rich afrs are when that either drips or floods so to speak. My brother had a similar issue. It ended up being one of the enrichment triangles on the side of the carb. If mine idles between 13-14 and is good on boost and cruise I don't bother.

[casper]

Don't no where I pulled that one from then.

[Wallace]

the auxiliary venturi is where the discharge nozzle is, right in the middle of the main venturi! when u open it up"u,ll see the fuel mixture coming out! it should,nt drip at idle or just off idle....if it does its more than likely ur needle and jet...dirty or worn! with regards to the acc.pump jet i think squirting towards the throttle plate is correct!

Thanks Michael that's really helpful

[Wallace]

the auxiliary venturi is where the discharge nozzle is, right in the middle of the main venturi! when u open it up"u,ll see the fuel mixture coming out! it should,nt drip at idle or just off idle....if it does its more than likely ur needle and jet...dirty or worn! with regards to the acc.pump jet i think squirting towards the throttle plate is correct!

At idle, nothing coming through.....

At even the slightest bit of throttle (perhaps not even 5mm movement) a constant stream of fuel and that is stream not 'mist' or 'squirt'!!!

So am i to assume this isnt right?

I have changed the discharge nozzle with another that i have, and still the same

[Wallace]

Including the above.............i've also changed the jets over as above.

The car now idles very smoothly and i'm getting good rreadings around 14.1

So I'm now spec'd with: a/c=125 & 1st Stage=100

But the afr's are still 10.0 with a minor change now to 10.5 and maybe 10.7, this is all taken at part throttle around 2500-3000rpm......

Can you offer me any further advice please?


Cheers

[casper]

Have you set the acc pump.?measured your main with a drill bit?

[Wallace]

Have you set the acc pump.?measured your main with a drill bit?

Yes.............to a point! i've adjusted it today numerous times, and also either fully in or out doesn't make any difference

Convienced i'm not setting it correctly,still not overly sure where the drill comes into play COCK - Can you explain in idiots terms?


I'll also check the gasket/diaphram isn't faulty tmrw

I haven't actually measured the main with a drill - but will tmrw

[Wallace]

https://www.rtoc.org/boards/showthread.php?t=460

Having re-read this article, its obviously gonna be a case of trial and error

I know James has tried explaining the acc pump set-up, but i'm just not gettting it

If you guys could break it down to numpty talk for me, then i'll adjust it again tmrw and just keep playing with jets till i hopefully get the right kinda readings

Thanks again...............off to work now so roll on tmrw

[casper]

Hi mate,just Google solex dis and look at the first few links,plenty of diagrams that explain it.You might be better off waiting till your engines run in,then fuel for the boost your planning on running,get your wot sorted first then take it from there.

[Wallace]

Hi mate,just Google solex dis and look at the first few links,plenty of diagrams that explain it.You might be better off waiting till your engines run in,then fuel for the boost your planning on running,get your wot sorted first then take it from there.

I'll have google now........

With regards to setting it for WOT, I obviously wanna get it set right for part throttle because I've 500 odd miles to bed the eingine in,and its not gonna do it any favours the ways its fueling at the minute

[casper]

If your reving it to 3k with a t2,is that on boost?What's the afrs at say 60mph in 5th.?

[Wallace]

Only just hitting boost really, it depends how its driven-and I'm drivimg it like a grandad cause the boost is turned right down for the engine to bed in

I've not even gone over 40mph yet bearing in mind its not MOT'd I'm just pushing my luck on a private road

[Wallace]

[casper]

[s3irios]

I had/have same issue, i even strted a thread with no success. I have same lame ultra rich 10s' readings too. I tried what gtjosh if i remember correctly said changing the triangle part (enrichment chamber) with no success. Carb has been cleaned numerous times, it looks spot on too. Can't really address the issue anymore. It's annoying as hell, it's expensive as hell (consuming that much fuel at little or no boost-wtf?) AND is making the car actually slower. In between gears and at low-middle revs the car is laggish like hell and really slow compared to how it was some years ago before the problem pops up.

Yes i know i didn't exactly give any solution, but wanted to inform you that there are others out there with same problem


Ohh almost forgot . The ultra rich afr problem lead to my piston rings going off. Now except the excessivce fuel consumption i have excessive OIL consumption too

[StuHERTS]

Congrats on your MOT pass Wallace
Thought id get in first lol

[Wallace]

I had/have same issue, i even strted a thread with no success. I have same lame ultra rich 10s' readings too. I tried what gtjosh if i remember correctly said changing the triangle part (enrichment chamber) with no success. Carb has been cleaned numerous times, it looks spot on too. Can't really address the issue anymore. It's annoying as hell, it's expensive as hell (consuming that much fuel at little or no boost-wtf?) AND is making the car actually slower. In between gears and at low-middle revs the car is laggish like hell and really slow compared to how it was some years ago before the problem pops up.

Yes i know i didn't exactly give any solution, but wanted to inform you that there are others out there with same problem


Ohh almost forgot . The ultra rich afr problem lead to my piston rings going off. Now except the excessivce fuel consumption i have excessive OIL consumption too

Corrr mate unhappy days to say the least

I cant offer any solutions myself yet - but, i think it is a 3 stage attack for me........

(1) Adjusting the accelerator pump - trial and error i suppose and in effect ignoring the 5mm setting

(2) Reducing the main jet

(3) Enlarging the a/c jet

If i have success then i will of course update this thread and hopefully help you out too

[Wallace]

Congrats on your MOT pass Wallace
Thought id get in first lol

Yeeeeeeeeeeeeeeeeeeeeeeah boi

Not that i'm bothered or anything

At least now i can sort the fueling out and give it a good trial rather than - just past your road-turn round-just past my road-turn round-just past yours-just past mine-just past yours-just past mine

[Tony Walker]

Prob best to try a spare carb then swap and change bits and see what cures it.
It may be a flaw in the carb body we havent yet got involved enough to cure. i wouldnt try reducing main jets and changing air correctors from standard. they are those values for a reason and should fuel correctly with those jets, if it doesnt then theres a problem.

[Tony Walker]

Either way...... good luck

[Wallace]

Cheers Tony.........

I'm gonna have a play about anyway, with afr gauge and more importantly not driving it like an idiot, it'll be good learning for me

I have however got a spare carb so tmrw will really get involved and see if i can get it fueling well

As for now though, as you'll see above its past its MOT Beer o'clock

[s3irios]

Did all 3 steps you mentioned nada. Well thy might work for you but they sure didn't change anything to me. A spare carb is the best solution.

[Wallace]

Right ok.......well if you've tried and its not worked then the spare carb will be my first step!

[Wallace]

Sooooooo, I fitted the original carb and the afr's changed COMPLETELY!!!!!

Basically far better, and its given me a better base to work from........

As far as i'm concerned the old carb must be 'faulty' for what ever reason, i will eventually get to the bottom of it by measuring the bushes and checking seals etc etc etc.................and i'll let you know what i find

Once ive re-adjusted the acc pump again (been fiddling with it to see the differences!) and given the carb yet ANOTHER clean.........as i've got issues with the idle jet getting blocked by swaf, but once i've cured that i be a happy boy

[StuHERTS]

Thats good news mate!
Im about today if you need a hand.

[Tony Walker]

u

[Wallace]

Seem to have reached the goal,as such.......

Done a fair few miles today - I think alot of it, is learning how the carb fuels and behaves, which is a bit of fine science for a newb

Idles beautifully now - cruising i'm seeing anything from 12.0 - 15.9 but VERY much dependant on the gear im in and the amount of throttle (obviously!) - but over run has improved and will mostly remain around idle afr's (13.8-14.2) but can occasionally sink to 16.0-17.0 etc!

But all in all very happy, got the afrs i should so i can now get some miles on the engine and then start playing with the boost and then the fueling all over agin

THANK YOU ALL FOR THE INPUT

[Jonny5]

Good news mate, lovely motor too

[Wallace]

Good news mate, lovely motor too

Cheers

[Tony Walker]

Sounds about right now, it's a bit of cat and mouse trying to keep up speed and efficiency :-) mine works best about 70 in 5th :-) luckily lol

[Alex]

That's carbs for you!

[Wallace]

It has completely shown me why the cars got a bad rep in the old days,for the head gasket going,obviously as result of things not being set-up right!

With the afr gauge, it shows they are so clearly vunerable to poor fueling, which obviously then leads to a world of pain and expense............

I never thought that the carb would be so changable to be honest,and lack consistency..........

[StuHERTS]

Im glad you've got it sorted mate..
because you can then do mine!
LOL
Hoping to order my AFR within the next 2 weeks..
Anyone want to buy a Scott Scale 29er 2012 Mountain Bike?