My cars shit on fuel to the point where im putting £50 through it in a week to do about 120-140 miles. What can i do to improve this? Which way do u adjust the mixture screw to make it rich/lean?

Go into your profile and add a signature. Put down what model you have, as it's more likely to get a response if people don't have to keep looking back or remembering what engine you have.

1.7? There are quite a few threads on shagged Z10 Solex carbs, there's even a practical guide in the technical section.

£50 means nothing to me (I don't know how much a litre costs in UK anymore) and for all I know petrol could be cheap/expensive depending on the grade and the local price. How many litres are going in, then I can work out the MPG. It sounds shit mpg-wise, but without putting some sort of figure on it we don't know precisely how shit it is. Again, what sort of miles is it? Local stop/start or motorway cruising? That can go +/- 30% either way.

Anyway, there is probably more work to it that just twiddling a screw.

Hello, is that the good old 1.4?? Probably it needs new carb-to-inlet manifold gaskets which aren't too hard to get or copy and its worth checking for leaks in as many places as you can. You can listen for air leaks. CBA found that my 1.4 was visibly leaking petrol into the inlet manifold so I would have a look for that, too. Adjusting the screw on the 1.4 never did anything in my hands, really. Gasket sealant will help with air leaks, etc.

Yes proper figures please, mpg or km/l .

Assuming £1.30 per litre and using the best case 140 miles, gives 16mpg which does indicate a fault unless you are on a race track or treating the road as one.

Air leaks and float levels would be common problems with the Renault engines.

I worked it out to be 90 ish (my mile counter doesn't work) on 15 litres of fuel, so works out to be around 25mpg from a 1.7 on a solex twin choke. Getting a set of bike carbs for it soon so that should improve it hopefully