Carb fault?

[Forkie]

   Out with the screwdrivers again!! Took her out for a run,seemingly ok. But when in neutral,at traffic lights etc idle speed was high again... So in short,if i set the idle speed when cold,it goes up when hot...if i set it when hot,theres no idle after choke has been pushed in?!? has any one any ideas ?
     regards,nig.

[David Withers]

Hello Nige,
I\'m confused.  You put up two new Topics yesterday about setting the hot/cold idle speeds in a 1975 2500S Auto Estate but in fact these seem to be follow-on postings about the same problems you were suffering 18 months ago with a 2500S engine in a 1972 Stag!
Whether in a 2500 or a Stag, my posting of 30 April 2007 should help you set up the choke mechanism.  Just do a search on \"carburettors\" and take a look at \"Choke Setting\".

[David Withers]

To save you searching, here\'s the page you need:&nbsp; <A> http://www.t2000register.org.uk/forum/f ... asp?TID=54 8&KW=carburettors&TPN=1 </A>

[Forkie]

&nbsp;&nbsp;&nbsp; Hi Dizzy,
&nbsp;&nbsp; Thanks for your reply,even though you\'ve confused me now,i\'ve never owned a stag !! I will try your suggestion, although Gavins problem doesnt quite match mine. Mine needs very little choke for a very short period (almost push in straight away) and she will run fine,save the idling bit!!
&nbsp;&nbsp; Incidently,the two posts were meant to be one <IMG>,didnt realise i only had so much room to type. I\'m as green on these things as i am T2000\'s <IMG>
&nbsp;&nbsp; Cheers, nig.

[sorbs]

Worth checking the mixture isn\'t too rich, have a look in the exhaust, if its black and sooty after a longish run, its too rich.
My car was idling a bit lumpily and would start to misfire slightly after idling for a while. Only took about 1/2 a turn on one mixture screw to give a nice smooth idle, and now the exhaust isn\'t full of soot either!&nbsp;
&nbsp;

[David Withers]

Nig, I owe you an apology!&nbsp; The poster with a 2500S engine in a Stag goes by the name of \'Nige\' and your postings seemed to&nbsp;read straight on from his (or hers)!!&nbsp; Quite a co-incidence, but it doesn\'t take much to fool me anyway.
Not sure why your typing wouldn\'t fit into one posting.&nbsp; There\'s loads of room, as can be seen from my sometimes very lengthy postings!&nbsp; My own little problem is that hitting \'Return\' on the keyboard gives me <U>two</U> line spaces when&nbsp;I only want <U>one</U>.&nbsp; <IMG>
Best wishes for a quick carb cure.

[Forkie]

&nbsp;&nbsp; No problem Dizzy, at least it cleared the stag bit up,i hope my carbs are just as easy (some how i think not!!!)
&nbsp;&nbsp; cheers, nige.

[Forkie]

&nbsp;&nbsp; Thanks for the reply Sorbs. She was definitely running rich,all the tell tale signs were there,hence i decided to have a go,and as i mentioned in original post i took the haynes route and adjusted them so lifting the air valve caused slight increase in speed,returning to normal. Whether having two carbs is confusing me ( last time i played with carbs it was over 10 years ago,allegros chevettes and mk1 cavaliers <IMG>&nbsp;all having singles!) im not sure. All i know was it was idling fine before my hands went near them!!!
&nbsp;&nbsp; It will be a couple of weeks before i get time to have another go,in readiness for its first m.o.t. with me ( time to tell if i bought a basket or not !) cheers,nige.

[sorbs]

To be honest, lifting the air valves on mine seemed to produce the correct response from the engine even when it was too rich so I fiddled with the mixture until the exhaust and plugs looked about right.&nbsp;
The carbs could be balanced better but the car goes well and averages about 29mpg so I\'m not complaining.&nbsp; I have the advantage of my car not actually having to meet any emissions limits so can set it up to run properly without having to worry about CO levels.
When the car was running rich, the rear 3 plugs were black, the front 3 were normal so I figured the rear carb (the one I\'d messed with to cure a fuel leak) was overfuelling.&nbsp; Leaned it off a bit & all OK!

[Mike Stevens]

Hi all,
I\'ve never found the lifting pin very helpful either.&nbsp; I think it has too much travel and it\'s all too easy to lift the air valve too much.
What the \'experts\' seem to do it remove the dashpot thingy on the top , lean it over and use that to lift the air valve.&nbsp; I think it\'s easier to judge the amount of lift that way.
What I tend to do is start too rich on each carb and then wind in the adjusting screw until it goes too weak - which you can tell by listening, then wind out a couple of flats.&nbsp; Do this on each carb.&nbsp; The theory is that the highest idle speed is around the optimum mixture, going too weak makes the idle speed drop but going too rich doesn\'t make so much difference.&nbsp; So the too weak point can be detected by idle speed - going back a couple of flats puts it on the rich side.
I have also found that modern petrol (or maybe this adjustment method!) can make the engine run-on.&nbsp; Running a bit on the rich side seems to help this and is FAR better for the engine that too weak!
Cheers, Mike.