Weber help

[Patrick Fletche]

I have tried posting this in road cars, to no avail.
Basically I have a Caterham with twin Weber 40 DCOEs which are misbehaving.
Does anyone know of a person near Leamington Spa who can sort this?

Thanks.

[phoenix]

As I live 'down south' I can't help you with your request, but as you are now in the technology forum there may be someone here who can help you sort your problem.

First of all, what are the symptoms?

[Patrick Fletche]

Originally Posted by phoenix

As I live 'down south' I can't help you with your request, but as you are now in the technology forum there may be someone here who can help you sort your problem.

First of all, what are the symptoms?

Lots of popping and banging.
Engine cuts out when cornering (interesting!)

[tristancliffe]

Float heights correct?
Fuel pressure correct?
Angle of mounting correct?
Rubber vibration dampers fitted and correctly adjusted (not too much crush, not too loose)?
Jetting correct?
Idle mixtures set correctly (by a proficient carb person - don't assume that mobile tuners actually know anything about carbs!)?

[Tim Falce]

Running too lean or timing too retarded or sucking in air somewhere it shouldn't or blocked jets. Check the inlet manifold isn't loose or even exhaust manifold leaks can cause these symptoms.

[GORDON STREETER]

Has it got the old sandwich plates with O rings on both sides? If so throw them in the bin and buy the ones that have the rings bonded on. Webbers dont give a lot of trouble so are you sure its a carb problem ?

[SidewaysFeltham]

Could be a fuel feed blockage; e.g. filter, dirt in the line/tank outlet.

However, the old dictum is never assume anything!

When Ford were selling the early Lotus Cortinas, Ford dealers were so perplexed by Webers (and twin O/H cams, etc), their first port of call was to always blame the Lucas distributor (Ford by then had bought Autolite and standard kit was their naff distributor; Yuk! And then the twin 40s.

Loads went back to the Parts Recall Centre at Dunton in Essex and well, sort of found their way onto loads of racers!

A Weber, being fixed jet, can only really "misbehave" as you state, if either a jet or internal drilling passage is blocked. Blow it all out with an airline.

If the carbs are very tired, then yes, the throttle butterflies can show wear: bushing will solve this, with a new shaft. Cheap as chips.

Probably something else.

The flexible joints really only prevent "Frothing" from vibration: which can of course fuel starvation.

Could be faulty ignition: find seomone with a decent rolling road and analyser (who knows what they are doing!) and can run the car under load.

Agree totally with Gordon re the Pirelli Joints: unlikely that yours is fitted with the sandwich plates, as they went out long before Caterham took the manufacturing license.

[phoenix]

Originally Posted by Patrick Fletche

Lots of popping and banging.
Engine cuts out when cornering (interesting!)

Cornering problems - I would look at float levels first. Dead easy to do yourself.

[grichie87]

Throttle bodies?

[GORDON STREETER]

Patrick . Webers dont actually go wrong unless somebody has been sodding about with them. Apart from needle jets wearing ( doesn't seem your problem ) butterfly bushes do wear out but only after serious mileage.
They are very easy to work on as they were designed for racing and you can change jets and chokes quickly at the track. They are not very high tec and haven't changed much over the years. Wip the main jets out and check that they are clear . It sounds like a weak mixture that could easily be caused by something else (as has been pointed out by the other posts) Has the car been laid up and got stale fuel ? has it got any diesel in it ? you may laugh but I have seen this loads of times. Let us know and I am willing to bet that the actual carbs are ok. If its a crossflow make sure the inlet manifold gasket is ok. Last of all is this a new car to you and did it come with this trouble ?

[Notso Swift]

Agree Webers don't really fall out of tune, but a float being craked is not unheard of... (which would be the opposite problem to what you have)

[GORDON STREETER]

Notso haven't the solid plastic floats got round that side of the world yet

[Notso Swift]

D'oH, maybe, but I've been Fuel injection for a while... more than 15 years, infact.

[tristancliffe]

Originally Posted by grichie87

Throttle bodies?

He might want the extra power that carbs will give, or perhaps his series requires carbs in the tech regs.

[Notso Swift]

Originally Posted by tristancliffe

He might want the extra power that carbs will give, or perhaps his series requires carbs in the tech regs.

I don't know how anyone gets extra power out of carbs, indeed, a perfectly set up carb or TB should give exactly the same power. More power from a carb means the TB set up is wrong, simple as that. (Disclaimer statement: Of course TB's have less flow restrictions so they can offer less pressure drop for a required flow, which gives a greater potential for power, but that is miniscule compared to sizing the whole lot in the first place.)
At part throttle TB's are actually easier to set up, but a "perfect" carb should still get exactly the same power.

Tech regs, this is a legitimate reason, but power is not