Weber 45's spitting back 1000 rpm to 2500rpm

[M11rf]

Engine is a 2.0 pinto.

The carbs are spitting back from around 1000 rpm to 2500 rpm.

It ticks over just below 1000 nice and even, but if you feather the throttle then it will spit back until around 2500 when it seems to clear and revs smoothly up to the red line.

If you are aggressive with the throttle from tick over and press it down, it will shoot straight up and revs good.

I think there is too much air and not enough fuel going in when you open the throttle slowly...

What can cause it?

Any ideas on fixing it?

[Graham]

its going lean in progression, you need to change the idle jets for something richer and reset the mixture screws

[M11rf]

Cheers Graham... I had an idea you would reply

I will have to pop the tops off the carbs and see what idle jets are in there... Would you go 1 size larger? 2?

[Graham]

weber idle jets have a weird numbering system 45F9. 50f4 ......etc.

the jets dont follow a logical numbering system where you can just use a bigger number

but if you tell us whats in there someone will advise, might also be an idea to give us some idea what they are fitted to

[M11rf]

I will have a look tomorrow and report back... Carbs are fitted to a 2.0 pinto. Only thing i am certain of is that it has an RL32 cam.

[sr412]

Sorry to hi jack this thread but I'm having the Same problem

My engine is a xe on 45s it's running a little lean the pilot jets are f8 55 what would be the next step up from these.

Also would the ecu map on my mbe cause any issues with mixture?

[Miniliteman]

Spitting back in the progression phase normally is due to a lean mixture, retarded ignition or both.

If a 55F8 is too lean try a 55F9 or a 55F6.

[dazzle]

Interesting this one as I've just had the same on the rollers!!
MK2 RS2 with Pinto and twin 45 webers.
Had exactly the same, took the jets out and they were 55 f8.
We didn't have a lot of choices in the 'cupboard' so ended up fitting 65 f6's.
It was a lot better after adjusting the mixture screws and was no problem on the rollers.

Not quite as good on the road because when sat at constant speed, throttle pedal is only just 'feathered' and it's right at the point of change over between idle and mains i.e. progression phase!

So I'll keep an eye on what you guys come up with

[boXXer]

i think i have found an answer to alllllll your problems....







































































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=

[M11rf]

So if you fit all that stuff, it turns your car into a left hand drive?

Nahhhh... Don't think i will bother

[boXXer]

Nooooooooooooo, it makes your dash lights amber

[dazzle]

Nooooooooooooo, it makes your dash lights amber

My dash lights are already amber?

[Erikmex]

Throttle bodies will do exactly the same thing if not mapped right

[boXXer]

My dash lights are already amber?

your clearly missing the point. It enables you to change to ANY colour you wish

[dazzle]

your clearly missing the point. It enables you to change to ANY colour you wish

Aaaaah, I see! Quite like the idea of blue lights..............

[Blower]

Ive got a 2.1 (2.0) ... FR 32 cam ,and twin 45s

My problem is spitting back under 2 - 2.5 thousand revs , ive also got the Famous 55 F8 Idle jets

Had em out today to check the size , also removed a few other screws and fitted new seals

... Re-fitted and the car ran totally different , the spitting was less , somtimes not at all , a joy to drive

I dont believe i had any air leaks - so ... been doing my homework on jets

Im going to order some 60 F14 or F12 , .... any 1 agree - disagree

[Miniliteman]

With that spec you should not need 60F something idle jets.
Try 55F6.
Do you have a modified distributor for use with twin carbs?

[Blower]

The distributor is the Electronic Motorcraft - 6 wire off the sierra

So , your saying the 55 should be up to the job , just need to find the right F...ing F

[Miniliteman]

55F6 (6 as in six)

[Blower]

55F6 fitted today ...

Must say they make it run a lot better , which i really wasnt expecting , So... hats off to you Leon

First fitted , and the engine was Hunting , revs were up and down , so wound the mixture screws in and out , and i think ive got a nice medium

Ive got a Oulton Park show this weekend , so I will take my favorite screw driver with me and have a play , will be a good test

[M11rf]

Nice one

[Blower]

Well its still hunting , rev range at Idle is up and down between 9000 - 1200 , but to start it up from cold is instant , on the button

the thing is it runs so much better , but obviously the Hunting is causing concern / Rich /lean running

For the sake of another tenner or so / any 1 recomend any more jetting mods

[Miniliteman]

Check for air leaks and also double check the balance between the carbs; hold one carb with one hand and try to wiggle the other up and down. If you can wiggle it just a bit then that is enough to cause an imbalance.

[piekey]

If you have choke linkage stuff still set up on carbs & do not use a choke cable/cold start system, i would suggest purchasing a choke delete kit from Southern Carbs, this does away with all the choke bits.
Far bit of kit to fit on the bench, but it's well worth the investment.
90% of the phoofing went away straight away on my xflow set up.

[Graham]

If you have choke linkage stuff still set up on carbs & do not use a choke cable/cold start system, i would suggest purchasing a choke delete kit from Southern Carbs, this does away with all the choke bits.
Far bit of kit to fit on the bench, but it's well worth the investment.
90% of the phoofing went away straight away on my xflow set up.

your about 5 years late in replying to this lol!

[Blower]

your about 5 years late in replying to this lol!

Better late than never

[piekey]

Better late than never hah.
Webber didn't have these kits 5 years ago, so, upto the minute concise info is the way forward.