Anything and everything GT6.

Section : Carburettors

Carbs again

Posted By : David Lloyd, 04-Jun-2007, 01:34pm

I broke down at the weekend as soon as I got onto the motorway. I went to accelerate past a lorry and had to give up as the car wouldn't move any faster. It then just got worse and worse such that I had to call it a day when I couldn't get over 30mph.
The next day I tried the car again and I noticed that with the choke out the car ran fine so something must be up with one or both of the carbs? In town I could smell the rich mixture so maybe one carb needs the extra and the other is running over rich. The car is running Strombs 150's, and I suspect the diaphram needs replacing which I'm hoping will be easy for someone who hasn't done this before. Maybe whilst I've got the top off I should do a bit more without upsetting too much? If I do take the top off, is there a gasket that needs replacing? Does anyone have other opinions on this work or the problem?

Thanks all

David

Followups :

Carbs again

Posted By : Colin Wake, 04-Jun-2007, 02:03pm

Chqnging the diaphragm only takes a few minutes, and a screwdriver.

no gaskets etc needed, just make sure the pips on teh new one line up with the notches in the carb body and the piston.

Cheers

Colin
- Carbs again
  
  Posted By : David Lloyd, 15-Jun-2007, 12:58pm
  
  Thanks Colin, I finally got time to do this and sure enough it was quick and easy. Only trouble is the car still runs like a dog. If the choke is in the car gets to about 2500 revs and then sounds as though its running on air, just wheezes. Carb out and she sounds better though obviously rough. I've now changed in total the fuel filter and the diaphrams.
  
  Any suggestions anyone?
  
  Thanks in advance
  
  David
  - Carbs again
    
    Posted By : Brendan Delaney, 15-Jun-2007, 06:34pm
    
    OK, car runs badly and won't accelerate, but sounds better when the choke is out (may be a mixture thing Or just higher revs without load).....
    1. Nothing jammed? Jets, choke linkage etc....
    2. Compression OK in all 6 cylinders, is a valve blown? Try taking one lead off and see if they all have an equal effect.
    3. Could there be a crack in the manifold or a leak in the manifold Gasget letting air in at higher revs?
    4. Is it electrical? - check points gap, plugs, HT leads, check for dirt or arcing in the distributor cap. Has the ign timing slipped on a loose distributor pedestal?
    Just go over everything systematically.
    - Carbs again
      
      Posted By : Gavin Barnett-Smith, 15-Jun-2007, 10:34pm
      
      I had similar problem with my Vitesse. When examining the throttle linkage I noticed that when I 'blipped' it above idle speed that one of the 'u' clamps on the interconnecting bar that connects the carb throttle spindles together had worked loose and was allowing the throttle spindle to slip and stay closed at anything much above idle speed.
      - Carbs again
        
        Posted By : Chris Taylor, 16-Jun-2007, 03:00am
        
        Sounds like a fuel starvation problem. Plenty of previous posts on this issue. Check from fuel pump forwards. Check for a blocked filter in the pump, and that the pump is giving a good squirt as the engine is turned over. More likely to be a build up of muck in the float chamber(s).
        I suggest you get a gasket set on hand before dropping the float chambers. It can be done in situ without removing the carbs from the manifold, but be careful not to lose any of the retaining screws as it is a little awkward working upside down and partly by feel. Replace the O rings around the base of the jet (if there are any, depends on the type of Stromberg you have, CD or CDS) and also check for any muck on the INLET side of the floatchamber needle valve. Use a new aluminium sealing washer behind this if you can, or put a couple of turns of PTFE tape (teflon, available as a plumbing item from B&Q etc, and useful for sealing threads in all sorts of situations) on the threads when reinstalling the valve.
        
        Carbs again
        
        Posted By : David Lloyd, 31-Jul-2007, 12:50pm
        
        Finally got some time to take the carbs off the car and use the servicing kit. I was useful to take them off to get a good look at them, they do seem to have been previously thrown together. 3 things:
        
        1) I found crud on the bottom of the needle (hopefully the source of my problems)
        
        2) The bar that links the throttle between the two carbs is joined using a sprung type of metal in a M shape at both ends (unlike my manual which has it on just one... however I think the carbs may be for a Vitesse as they are number 3224). Anyway one of the M shaped links is not set right and therefore the bar does not sit perfectly in line... should I replace these with new or just bend it back...I don't know how fragile they are.
        
        3)One of the carbs has a brass cylinder that hangs from the top of the float chamber just beside the jet adjusting screw (picture enclosed). The other carbs did not and just has a hole at the top. The one with the cylinder had the floats sitting 18mm above the base of the float chamber as the manual states it should be, the other was much higher at about 25mm. could this have caused starvation by not filling the chamber sufficiently am I missing a component in the one without the cylinder?
        
        Any answers welcomed....
        
        Cheers all
        
        Dave
        
        Carbs again
        
        Carbs again
        
        Posted By : David Lloyd, 31-Jul-2007, 01:03pm
        
        ....And pic of the the sprung links...
        
        ... don't know why dinner smelt of oil & petrol??????????
        
        Carbs again
Carbs again

Posted By : Ian Horsfall, 31-Jul-2007, 03:30pm

David

There is a saying - "it's always the electrics". The fact that this happened suddenly is more indicative of electrics, also even with one carb completely out of action you should be able to get well over 30mph.

Poor running which is solved by pulling the choke out just means that the mixture is not igniting properly and all sorts of things might cause that including valves and electrics as already mentioned. I had a similar problem on mine and it turned out to be the coil. You might also check points, condenser etc at the same time.

Check that you have a good healthy spark, I would agree with the previous post about checking that all the cylinders work. If you want to avoid shocks a better check of this is to spit on the manifold pipes close to the head when the engine is running, this easily shows which pipes are hot and which cylinders are firing.

Ian H
- Carbs again
  
  Posted By : Peter & Mick Lewis, 31-Jul-2007, 09:39pm
  
  is the float height wrong because the float is upside down ?? they fit both ways !!!
  not cerain about the brass extension,, where does it vent or feed to ?
  the flexi links are quite tough made of spring steel and can be carefully reformed,
  make sure each rod fits into 2 of the holes each end of the M before tightening the screws
  what ever you must have the float height right, however achieved,one sealing washer and a straight
  float arm should give the right level.....
  the brass cylinder is the suply to the choke, should have a ball held in place with a pin,the ball should
  be loose and rattle in the tube. have both carbs got a choke ?? some only had choke on one of the 2 carbs
  might be why one of yours does not have the tube ??? peter
  - Carbs again
    
    Posted By : Chris Taylor, 31-Jul-2007, 10:25pm
    
    From the pics it seems that only one carb has the choke, which was the standard arrangement when Triumph used two of these carbs. The black pipe between the two carbs transfers the rich mixture to the other carb, so you do not appear to be missing anything if the carb WITH the tube is the one with the choke valve.