mk2 8v Webber conversion mediocre result

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scirocco_ne
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mk2 8v Webber conversion mediocre result

Post by scirocco_ne » Wed Dec 19, 2018 11:10 pm

As the title states i fitted a weber conversion to the mk2 a few months ago (new) and its reliable and solid now but i just cant get understand why its hesitant at times.

It runs great but has one little niggle i hate. If you literally flat to floor the car whilst driving it will always hesitate for a split second then deliver perfectly... I have fine tuned it to death now on the screws and it has done nothing.

Day to day driving this is not noticeable but it always does it flat out accelerating.

Is this a common experienced issue? could it be the silly rubber adapter although it looked fine on fitting? I am stumped really as its a fixed jet so theres very little you can do and i know alot of people dont even tune them.

Thanks
Mick



blakey
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Re: mk2 8v Webber conversion mediocre result

Post by blakey » Thu Dec 20, 2018 2:55 pm

Could the issue actually be on the ignition side - check the vacuum pipes to the distributor, and the free movement of the base plate in the distributor. It could be a delay in the advance of the ignition...

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chopperoli
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Re: mk2 8v Webber conversion mediocre result

Post by chopperoli » Thu Dec 20, 2018 5:28 pm

Common issue, AKA lean bog. If everything else on the carb is working and clean and all set absolutely correct, there are a few ways to address it.

Most effective way is by upping the accelerator jet aka pump jet, swap it for the next size up, e.g. if it's a 45 fit 50.

Is it a DMTL?



scirocco_ne
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Re: mk2 8v Webber conversion mediocre result

Post by scirocco_ne » Fri Dec 21, 2018 4:15 am

blakey wrote:
Thu Dec 20, 2018 2:55 pm
Could the issue actually be on the ignition side - check the vacuum pipes to the distributor, and the free movement of the base plate in the distributor. It could be a delay in the advance of the ignition...

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Thats a good shout pal thanks i will check the dizzy



scirocco_ne
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Re: mk2 8v Webber conversion mediocre result

Post by scirocco_ne » Fri Dec 21, 2018 4:18 am

chopperoli wrote:
Thu Dec 20, 2018 5:28 pm
Common issue, AKA lean bog. If everything else on the carb is working and clean and all set absolutely correct, there are a few ways to address it.

Most effective way is by upping the accelerator jet aka pump jet, swap it for the next size up, e.g. if it's a 45 fit 50.

Is it a DMTL?
Yeah It's a brand new Dmtl kit. I was offered a bigger jet by weber so i may take the offer up.

The set up seems all correct so i would assume it should be something else. Can the rubber sandwich plates cause issues like this?

thanks
Mick



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Re: mk2 8v Webber conversion mediocre result

Post by mark1gls » Fri Dec 21, 2018 11:53 pm

What is the CO setting?


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james butler
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Re: mk2 8v Webber conversion mediocre result

Post by james butler » Sat Dec 22, 2018 2:20 am

try weakening the mixture half a turn and see if the hesitation goes, it may be a rich condition


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scirocco_ne
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Re: mk2 8v Webber conversion mediocre result

Post by scirocco_ne » Sat Dec 22, 2018 12:03 pm

james butler wrote:
Sat Dec 22, 2018 2:20 am
try weakening the mixture half a turn and see if the hesitation goes, it may be a rich condition
I will try but the guy from weber and the carb dealer told me i was basically unable to adjust mixture on it without a jet change as the 2 screws relate only to idle or below 1800 rpm i believe. I tried and recorded all sorts of positions around the recommend in testing.

Thanks
Mick



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james butler
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Re: mk2 8v Webber conversion mediocre result

Post by james butler » Sun Dec 23, 2018 1:21 am

hes kind o half right.
the mix is mainly set by the jet size but the idle setting is adjusted by the mix screw and has a big impact on pick up and smooth running.
i had similar problems and was convinced it was running lean.
my grandad of all people mentioned just try screwing the mix screw in the other way and try it.
sure enough it ran loads better!
carbs are a learning curve but they are simple cheap things to mod
Last edited by james butler on Sun Dec 23, 2018 2:29 am, edited 1 time in total.


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james butler
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Re: mk2 8v Webber conversion mediocre result

Post by james butler » Sun Dec 23, 2018 1:39 am

definately check for air leaks as its a common reason for having issues with any carb.
spray carb cleaner on all the carb joints and see if the engine picks up or dies.
one thing you should also check is that the engine dies when you wind the mix screw all the way in.
I've set a few of these carbs up and have found some have had the secondary throttle plate set incorrectly giving odd issues.


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Jimbog
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Re: mk2 8v Webber conversion mediocre result

Post by Jimbog » Sun Dec 23, 2018 1:39 am

I have exactly the same thing with my new weber DMTL kit. Fairly annoying.