Twin Weber Carb Trouble

[Craig89 0]

Hi, im having a bit of trouble with the twin webers on my TU rallye. At around 2000 RPM they just start coughing and spitting but the car still seems to run ok. If anyone has any ideas on what it might be, that would be great.

 

Heres a video of what is happening:

 

View My Video

 

Cheers, Craig

[iamjackiechan 0]

have you had the carbs balanced and jets to suit you setup

[Craig89 0]

have you had the carbs balanced and jets to suit you setup

 

Yeah, set up by Sandy Brown. It used to happen every now and then which i could accept but it just has been getting more frequent

[iamjackiechan 0]

what fuel pump, pressure regulator are you running.

also may be worth popping the jets out and just having a general snoop around the carbs make sure nothing is damaged or not how it should be

[Guest steveontwin40s]

Hi, i had twin 40s on my 1.6 gti 205 and they used to backfire, i removed the carbs and found the inlet manifold gasket had a split in it, worth a look. plus have you got a adjustable fuel pressure regulator, it is very important 2 have it spot on. how long was it set up? they go out of tune so fast!

hope this helps.

[Bally123 0]

Air leak by the sound of it, you could try running the same conditions in the dark - chances are you'll see a spit of light with every cough, is the distributor and or servo connected to the manifold? (if so try blocking off the manifold tappings)

 

I would suspect Missab gaskets are leaking - but I have also had similar experience with a vacuum advance tapping on the manifold- this showed up in the dark as above

 

Good luck...

 

Bally

[Craig89 0]

Thanks for the replies everyone.

 

The gaskets between my manifold and carbs is quite thick and looks like a see through plastic material, when i hold it at 2k RPM in the dark you can see flashes at these gaskets.

 

The only hole in the intake manifold is for the vacuum for the brake servo and that appears to be sealed.

 

I will remove the manifolds and carbs and see what the gaskets are like.

 

Cheers, Craig

[MrG 3]

I'd agree with bally, sounds like one or two have failed.

[jonnygoodhand 0]

Yeah, set up by Sandy Brown. It used to happen every now and then which i could accept but it just has been getting more frequent

 

If you don't mind me butting in, they were originally set-up by Sandy, but were later fettled by Aldon Automotive, in order to get it past a rather strict MOT guy.

[MrG 3]

so could be running a bit lean?

[Craig89 0]

I have had the carbs and manifolds off tonight and checked all gaskets and they are fine, like new tbh, so cleaned everything up and tightened everything up, refitted them and tryed again. Still doing it unfortunately.

 

Next i wondered if it could be timing as i, fairly recently, changed the rotor arm. So i moved the rotor arm round a bit and managed to get it not to spit.

 

Im not sure if this is the correct solution of the problem though, is there an easy way of checking that my car is timed up correctly how it is now or how it was before?

 

Cheers, Craig