Carb problems

[Alec]

Hello !aj!,

you have got me with the two screws, but I'm not so familiar with your car, if an 803 cc engine then probably a H1 carburettor.

It should be obvious from the cables which is the choke and which is the throttle. By looking at which is which, it should be fairly easy to adjust the tickover. Unscrew the choke one temporarily and then try and get a steady tickover with the throttle one? Then reset the choke one, only this is done cold unlike most other adjustments which is done hot.

Alec

[!aj!]

It's funny but i can't see an adjustment screw for the choke. Both these screws affect the throttle. I've played around with them but it would help to know the difference between them and how to set them. The manual shows them - Fig. BB.3 , page 114 but doesn't explain.

[kittyfell]

Yes both will affect the throttle, but the 'choke' one should only do so when the choke is pulled. Normally (ie choke not in use) it should have a clear gap showing and the idle speed is controlled then by the non-choke screw.

[!aj!]

Yep had a thorough look, to see what does what and indeed top one adjusts choke and the lower one adjusts idle speed. Dare i say i think it's sorted!!! Thanks for everyone's help and hopefully there will soon be a very happy new owner for this old girl!

[kittyfell]

And the dripping fluid............?

[!aj!]

The leak was from the manifold/exhaust union. I've tightened it up and used some paste. Seems ok now the mix is right.

[mike.perry]

Run the engine up to operating temperature, take it for a two mile run.
The two small adjuster screws have springs around them. One screw tightens on to a cam. Slacken this one off.
The other screw controls the idle speed, tighten or loosen it until the engine ticks over smoothly at a reasonable speed (about 500-600 rpm). The first screw adjusts the engine speed when the choke is pulled out, this should be tightened down so that it is just touching the cam. When you pull the choke out you will see the cam rotate and lift the screw which will incease the idle speed.

[bmcecosse]

I think he sorted all that out 7 hours ago !!

[!aj!]

I've set it up so it runs pretty well but could probably do with fine tuning.

I tightened the mixture nut all the way in (it was so far out i couldn't believe it - we drove it 90 miles straight like that!), marked it and undid two full turns. It seemed to be hunting so i've actually turned it back in one full turn. Now i don't know if it's still too rich - not familiar with the correct exhaust note! It's certainly a hell of a lot better.

Just wondering how many turns everyone elses nuts are in/out? If that's not too rude a question!

[bmcecosse]

You just twiddle it up and down till you get the smoothest/fastest idle speed. You then take it for a decent run - and then have a look at the spark plugs. White is too weak, black is too rich - and light beige is just right!

[xpress]

bmc do you rate these colourtune devices , are they accurate?

i have an old hawk co2 gas analyser, with no instructions! what would be the procedure for using this?! regards.

[bmcecosse]

Colourtune is a complete and utter waste of money and time! At least - on an engine with an SU carb - since it comes with it's own mixture setting device - the lift pin!

[xpress]

yes, but the colourtune when adjusting the lift pin/mixture setting device will adjust to the correct colour to show you that the mixture is right, no? ok bmc, how does the lift pin method work?

[bmcecosse]

Engine hot and idling (so aftyer a at least a short run) - you lift the pin just slightly - if the engine revs pick up then it's a bit too rich, if the revs die then it's too weak, and if nothing much happens - it's just right! But the real guide to running mixture (because pin and colourtune only help set the idling mixture for you) is to take the car for a good hard run - then switch off and take the plugs out and have a look at the colour. White is too weak, brown-black is too rich, and light beige is just right!