Tu Carb Woes

[Guest rtsbasic]

Hi folks, this is my first post here I'm having some problems with the carb on my 1.4 TU engine, it has the Solex 32 34 Z2 carb, and I've noticed the 2nd valve (float I think the haynes book calls it) only opens 2-3mm on full throttle. I was under the impression it should start opening at 2/3 throttle, and be fully open at full? The primary valve/float operates correctly and gives its full range. Can anyone help me diagnose & fix the problem? Bugs me to know the engine isn't giving me 100% of what its meant to.

 

The carb otherwise functions correctly - starts easy from cold on the choke, once warm it idles quite well with the choke off. Little bit more judder than my old injection engine while driving, but I'm guessing thats normal with carbs?

 

I'm completely new to carbs, all my previous cars have been injection, but I don't mind taking stuff to pieces as long as I'm confident it'll go back together

 

Thanks.

Edited January 29, 2008 by rtsbasic

[RP1983 4]

I'm not sure i understand what you mean by float.? The floats cannot be seen until you take the carb apart.

 

Assuming you are refering to the butterflies not opening fully then have a look at the mechanism where the throttle cable connects, open it all the way(with the engine off) and you should see one part of the mechanism push against the part that opens the 2nd butterfly. (if you look you should understand what i mean)

Hopefully it will be something obvious when you look at it, they normally are.

 

Good luck

[Guest rtsbasic]

I'm not sure i understand what you mean by float.? The floats cannot be seen until you take the carb apart.

 

Assuming you are refering to the butterflies not opening fully then have a look at the mechanism where the throttle cable connects, open it all the way(with the engine off) and you should see one part of the mechanism push against the part that opens the 2nd butterfly. (if you look you should understand what i mean)

Hopefully it will be something obvious when you look at it, they normally are.

 

Good luck

 

Sounds like I misunderstood the haynes book - I assumed the bits sitting in in the middle of the carb were called the floats. What you assumed is exactly my problem, the 2nd butterfly doesn't open anywhere near fully.

 

I didn't know its opened by the mechanism pushing against a lever for it, I assumed it was internally linked to the main one somehow. Will have another look at it tomorrow.

 

Thanks

[stu_woac 1]

sure choke is fully off as the secound buttfly doesnt open when choke is engaged

[Guest rtsbasic]

Choke was fully pushed in, maybe its out of adjustment. Not that I have a clue how to check

 

The car was fiddled with to pass emissions at the MOT a few weeks ago, but I don't know what they did, as I only got the car a week ago. Maybe it has something to do with it.

 

sure choke is fully off as the secound buttfly doesnt open when choke is engaged

[stu_woac 1]

I've not looked at one for a long time but there is a external lever that is on the carb which tochs the part the choke cable goes to it shouldnt be toching when choke is fully off they may of thought it was the idle srew it aint its so ajust when the choke should take over in a way

 

 

play with the carb your see what I mean

 

 

this then engages and disengages the secound butterfly

 

 

hope this helps if not pm me I could pop over

Edited January 29, 2008 by stu_woac

[Guest rtsbasic]

Will have a play with the carb again tomorrow, now I know a bit more about it. Been studying the haynes book again, and I can see the linkage for the 2nd butterfly to open in the diagram now (I think, anyway). Will have a play with the choke as well to double check that. If I put the choke fully in on a cold engine though it doesn't like to idle, so odds are its working right.

 

Thanks for your help guys No doubt I'll be back tomorrow after inspecting the carb, with more silly questions.

 

Edit, just seen your edit, can't see the pics i think your linking to.

 

Hah, just noticed your only up the road really, maybe I should take the car up Dawlish way sometime

Edited January 29, 2008 by rtsbasic

[Guest rtsbasic]

Just been outside tinkering with it again, still not working right.

 

The choke is 100% off, the butterfly for it is completely vertical.

 

Interestingly, after shining a torch down the unit, even the main butterfly isn't opening 100%, more like 80%. The secondary one is only opening 10-15%. I disconnected the throttle cable and moved the linkage manually, and this is as far as they'll. And ideas on why this could be? The linkage assembly seems fine, and the rocker it uses to open the 2nd butterfly is being pushed on as it should, just it doesn't do much to it.

 

It was idling a bit rough today as well, none too even.

[applemobile 0]

sounds obvious, but is there anything blocking it?

[swordfish210 20]

if you dont have any luck fixing the carb then why not swap it for a more reliable Weber carb...it just so happens that i have one forsale wink wink cough cough hint hint http://forum.205gtidrivers.com/index.php?showtopic=85910

[stu_woac 1]

yes but it is abit on the dear side the carb woes he has will be a free easy fix no dout

[Peetypug 5]

i've got a part dismantled xs twin choke carb at the farm

i will try to get up there sunday to have a look at it and take some pics

but iirc they dont open to 100%/fully vertical anyway

[Guest rtsbasic]

Thanks for the replies.

 

Cheers for the offer swordfish210, thats a bit beyond my budget at the min though.

 

Nothings blocking it, most confused by it, everything feels like its operating well, and smoothly, it just doesn't open the 2nd butterfly much at all. Was offered a replacement one exactly the same except it works correctly, off an AX GT with the same engine. £20 inc a pipercross filter, couldn't say no really. Just hope its still tuned correctly, I'm hopeless with these carbs at the min. Means I have a spare unit to play around with and figure out how these things work as well

 

Is there anything I need to take into consideration when taking the old carb off and fitting the new one? Looks like a simple job, disconnect everything and undo 4 bolts, will I need to purchase a new gasket or anything to seal it against the inlet manifold? Or will instant gasket do the job?

 

Thanks again guys.

Edited February 4, 2008 by rtsbasic

[stu_woac 1]

its a large gasket to the the manifold so souldnt need a new one unless it really looks like it needs it, do you know if the carb has the larger jet fitted so the air to fuel mix is correct for having a piperX fliter on it ??

[Guest rtsbasic]

Not sure if it had the jet changed, from the look of it the filters been on there for quite a while and the fella I brought it from seemed to think it ran very well, so I can only assume so, unless there's a way to check without ripping the whole thing apart? Will there be any signs when driving whether its had the jet changed or not?

 

I remember on a mates Escort mk4, he bodged a K&N filter on top of the carb, and it promptly started running terrible. Juddering every-time the throttle opens up too quick, jumpy at low engine speeds with high loads etc. Apparently that was because he never got it re-jetted to balance the mixture, don't really want that happening here.

 

Will plan to do it without a replacement gasket then, don't really have £10 to spare for one unless it needs it at the min. Can always put some instant gasket over the old seal if its looking a bit worse for wear.

 

Thanks.

 

its a large gasket to the the manifold so souldnt need a new one unless it really looks like it needs it, do you know if the carb has the larger jet fitted so the air to fuel mix is correct for having a piperX fliter on it ??

[trogboy 17]

If it drives withought any flat spots then the jetting is probably correct. You can replace the bottom gasket using a thin smear of instant gasket - just make sure you use one that is petrol resistant. Smear it on and let the carb sit down on it then torque it up when the sealant has gone off.

[Guest rtsbasic]

Just wanted to add that today I got the replacement carb so took the old one off (much easier than I expected actually), and found out what was wrong with it. The mechanism it uses for the choke to stop the 2nd butterfly being opened had bent, and had a bad fracture line along it. So instead of putting on the other carb I got (curiously it was similar but different, didn't have the electrical connectors mine has, didn't have a vent hose either), I nabbed the bits to fix it, lined the gasket with a smear of instant gasket, bolted it back up, and now it feels 10x better to drive.

 

I also put the Piper filter on..but haven't changed the jets. Will this cause any problems? It drives without flatspots, revving cleanly without hesitation up to its redline, the coolant temp is fine as well.

 

And just to say..thanks for the help, not just this thread but reading back through a lot of older ones, I think I have a pretty good understanding of these engines now compared to a few weeks ago

[stu_woac 1]

Just wanted to add that today I got the replacement carb so took the old one off (much easier than I expected actually), and found out what was wrong with it. The mechanism it uses for the choke to stop the 2nd butterfly being opened had bent, and had a bad fracture line along it. So instead of putting on the other carb I got (curiously it was similar but different, didn't have the electrical connectors mine has, didn't have a vent hose either), I nabbed the bits to fix it, lined the gasket with a smear of instant gasket, bolted it back up, and now it feels 10x better to drive.

 

I also put the Piper filter on..but haven't changed the jets. Will this cause any problems? It drives without flatspots, revving cleanly without hesitation up to its redline, the coolant temp is fine as well.

 

And just to say..thanks for the help, not just this thread but reading back through a lot of older ones, I think I have a pretty good understanding of these engines now compared to a few weeks ago

 

 

if you want to jet up I have a few so just pm me and pop over or I'll pop over sometime

[Teacher 0]

Its been a while but if i remember correctly there is a cam mechanism on the bottom (?) of the carb which opperates the 2nd butterfly at approx 75% throttle. if this is jammed/bent/inopperative then this might be what is restricting the main butterfly valve and making the 2nd stay put.

 

just my 2 pennys worth

 

NOTE TO SELF: read the end of the thread even if it is late!

Edited February 20, 2008 by Teacher