Rebuilt carb problems!

[UnstableCable]

Hi all

After a bit more help as still having problems with my 5!

Had a problem with a rebuilt carb on the motor, wouldn't idle below 1500rpm and is lumpy ticking over. Drives fine and goes well once moving but just refuses to sit and idle!

Since I have stripped down the carb again, taken out all the jets and given it a good wash through with carb cleaner! Inspected each jet individually and replaced them one at a time into the carb. Carefully reassembled the carb put in back on car and now seems worse! Still wont idle below 1500rpm and is lumpy as!!

With the carb top off and looking down through the carb when it is running I can see shed loads of petrol coming from the round part in the centre which I have been told is not right and is due to the needle valve but I dont now which part this is and I cant find any mention of it in the carb rebuild thread on here! Could someone point me in the right direction as Im at a bit of a loss at the mo!

Please forgive my ignorence as carbs are completely new to me! :ashamed:

[car.crash]

remove the idle jet and make sure its not blocked.

[Brigsy]

You need to be checking the needle jet & acc pump jet seal as fuel shouldnt be dribbling down the carb body on idle. Drop the idle speed too this sometimes causes fuel to dribble in.

If they are both OK the carb body may be at fault, sometimes the aux venturi comes loose which is pressed into the carb :(

[UnstableCable]

remove the idle jet and make sure its not blocked.

Tried that and swapped it over for a spare as well but no better!

[5teve L]

Carb base may not be sealing. I smear a little sealant under the gaskets, just not the top one that mates to the carb, this usually sorts it.

[Markey Mark (BD)]

I've had this a few times, with a good clean of the needle valve and seal, idle circuit or the enrichment body i get the fuel to stop dribbling. It does take alittle time a fiddling and adjusting the mixture screw but it does go in the end.

[UnstableCable]

Carb base may not be sealing. I smear a little sealant under the gaskets, just not the top one that mates to the carb, this usually sorts it.

Ok Ill give that ago but the first time I put it back on it had new gaskets on!

[Adam 005]

Ok Ill give that ago but the first time I put it back on it had new gaskets on!

very unlikely to be carb base:)

[UnstableCable]

I've had this a few times, with a good clean of the needle valve and seal, idle circuit or the enrichment body i get the fuel to stop dribbling. It does take alittle time a fiddling and adjusting the mixture screw but it does go in the end.


Jeez sounds like a headache! And I thought I woulkd just be able to bolt it back on and happy motoring!:crap:

Fitted a new neddle valve with the kit but maybe its faulty, will test it and give it a good clean! Will also clean the other bits!

[Markey Mark (BD)]

Jeez sounds like a headache! And I thought I woulkd just be able to bolt it back on and happy motoring!:crap:

Fitted a new neddle valve with the kit but maybe its faulty, will test it and give it a good clean! Will also clean the other bits!

Its not too bad to do mate, just alittle bit of playing with the carb.

[UnstableCable]

ok much to the neigbours annoyance I have just been and tested the needle valve.

Took the top part off the carb put a clean hose in place of the fuel hose, put my finger on the needle valve (very lightly, not quite enough to push it all the way in) and blew as hard as I could and nothing got through. Not sure how that pressure would compare to the normal fuel pump pressure?

So I guess that rules that out!?

[UnstableCable]

If they are both OK the carb body may be at fault, sometimes the aux venturi comes loose which is pressed into the carb :([/quote]

Cant say Ive ever seen this carb run properly either, thats why I decided to rebuild it!
I did notice when rebuilding it that the centre part (Sorry dont know it proper name :o) where the fuel is drippling from can be removed via a screw behind the choke plate where as other carbs Ive seen have this part blanked off!

Could it possible this could be causing me problems, maybe??

[UnstableCable]

Hi all. After some more investigating Im still left with the same old problems!
Since starting this thread I have tried the following to stop the fuel dribbling from the centre of the carb on idle and to get the car idling better!

Tested the needle valve which was ok but still swapped for another which is known to be ok.
Swapped the carb body over to rule out faulty carb body.

The car is still idling all over the place and I think the brakes are occasionly going soft. Also when idling on the spot the car will sometimes cut out if the brake pedal is pushed!

Have swapped over the one way valves for some good ones but this has not helped.

Has anyone got any ideas that might help? Pleaseeeeeeeeeeeeeee!

[TNT ANDY]

A split in a pipe (vac) going to or from the carb?

Leaky inlet manifold?

Leaky carb base manifold?

Take out all unessential pipework and try again.

There may be more than 1 problem.

[modfather]

ok firstly i have added a pic to help identifiy the carb parts :)
also liam on here had a fueling problem (to much fuel coming in ) a while ago and we adjusted the the bit under the carb which has been circled red and that stopped the extra fuel going in. i might be wrong but i thought i would suggest it

[UnstableCable]

A split in a pipe (vac) going to or from the carb?

Leaky inlet manifold?

Leaky carb base manifold?

Take out all unessential pipework and try again.

There may be more than 1 problem.

Yeah I starting to think I might have more than one problem!
So if the inlet manifold hasnt formed a good seal on the head then it would idle bad?

Which pipe work is unessential and can be removed for the purpose of testing?

[UnstableCable]

ok firstly i have added a pic to help identifiy the carb parts :)
also liam on here had a fueling problem (to much fuel coming in ) a while ago and we adjusted the the bit under the carb which has been circled red and that stopped the extra fuel going in. i might be wrong but i thought i would suggest it


Ah good man, that picture is ace!

Have been wondering about the bar, I guess its just a case of playing about with these things!

[modfather]

Ah good man, that picture is ace!

Have been wondering about the bar, I guess its just a case of playing about with these things!


that bar should be adjusted so it looks like the 1 on this link

http://www.rtoc.org/boards/showthread.php?p=187386#post187386

[Tony Walker]

Any air leak after the throttle blade will cause the mixture to run lean and wont idle well at all. fuel will have to be dumped in to compensate. try spraying brake cleaner around inlet manifold, carb base, pipes on manifold(try clamping pipes to inlet manifold to rule them out) if this doesnt show anything, then the fault is within the carb. or maybe faulty pressure reg.

[UnstableCable]

Ok thanks for the info chaps, got more than enough to keep me busy for a few days!! ;)