Hi gents,

Firstly I want to thank everyone for being patient with me as I do have lots of questions to ask. Thanks for all the replies!

New question: When driving, after a burst of acceleration and then dissengaging the gear (neutral) to stop the car, the engine kind of splatters and then quits and stalls while I am still running.

This means that it is too lean right?? or does it mean that my fast idle pin is set so that my idle is too low?

Doc? anyone?

Thebest thing to do would be to set your carbies up from scratch and then at least you'll know they are OK.

Here's what to do:

1 Make sure your carbies are in good condition, putting an old carbie on a car is a waste of time as you'll never get it to run right. If your unsure buy yourself a rebuld kit first.

2 standard set up on twins is M needle and blue springs 2AH needles will give you a richer set up if your flowing a lot of mixture into a big bore motor.

2. Make sure that your manifolds is well bolted up and the gaskets are sealing correctly

3. Wind the jet right up then back it off about 11 flats of the nut, this will at least ensure the car starts when the carbies are fitted.

4. Bolt the carbies back up again making sure that the gaskets etc seal up well.

5. start the car and let it come to normal operating tempreature.

6 If using twin carbies disconnect the throttle linkage from one of the carbies.

7. Bring the car as best you can to normal ideling speed using the throttle adjusting screws

8. If fitting a twin setup use a flow meter not a piece of garden hose to balance the flow rates of your carbies by using the throttle screws.

9. so now you should have a car that is at more or less the right revs with balanced carbies. Next is the mixture

10. lift the piton on the carbie until you feel a slight resistance then lift it about 1mm more, if the mixture is right the revs should increase just a little. If it increases a lot the mixture is two rich so you will need to turn the valve seat up; if it slows or stalls them the mixture is two weak and you'll have to turn the valve down.

11 Remeber on twin carbies that you should keep the valve levels as close as possible and certainly no more than two flats of the nut differrence.

12 Now you can take it for a run, sluggish response at low revs but Ok at high usually means it's too rich so try another flat up on the needle. Also watch your tempreature aguge as lean engines will as a rule burn hotter than rich ones.

13 After a good 20kms drive or so jump out and listen to the exhaust note if it's hunting then you're proabably a little lean if it's pulsiing then a little rich. Now have a look at the exhaust and plugs, exhaust should be a mid grey colour, light grey to white too lean ;black and sooty too rich. Plugs should be light grey with maybe a redish tinge.

13. Any problems beyond that and you really need a gas meter or a glass spark plug to see what's going on in the chambers.

Above all else make sure you start with top notch carbies and good seals all round or you're going nowhere.

Wow this is great! thanks I will try tuning it again

Yeah at minimum if the carb hasn't been rebuilt for a while check that the needle isn't binding or the dashpot otherwise sticking, try the drop test and at the same time check the dashpot oil level. Just to be sure the carb is functional before going nuts tuning it. SUs don't like dirt very much so keep them clean.

Your problem sounds very SU like - I find quite often when you are on the highway for a while (like an hour or two at 4000rpm), then stop to a standstill the car always stalls, because the carb gets confused. I believe it is a voodoo curse, but maybe somebody has a technical answer...

Anto.

Oh and just for the record the drop test *is* a BMC endorsed test (see your service manual or Vizard), it is *not* what you do when you get fed up with bloody SU carbs.....

I will look at the manual about pulling the SU out and servicing/cleaning it. Thanks for advice.