1.3L Carb - Very poor fuel economy

[LeeOxley]

Looking for a list of reasons as to why my 1.3L might be getting only 17mpg. 150 miles to a fuel tank. Only mods are weber twin choke carb and a K&n Air filter. Doesn't misfire. Doesn't stink of fuel. Idles, runs and pulls perfectly in the day but carb ices over easily at night and has a flat spot at differing revs. No matter what time of day its always poor on fuel. I have tried to be more efficient with my driving but that only got me 167 miles to a tank so cannot call that conclusive really. Any help is appreciated.

[Waspy]

I know jack about carb'd cars. But if it's driving fine, perhaps a leak?

[lemski]

Chuck it on emissions. If its fine then theres gotta be a leak.
Maybe in a line under the car of the hose out the tank.

Was it OK before the webber?

[LeeOxley]

Before the weber I hardly drove it as the choke had died. (typical Pierberg) and before that the Head gasket went, I bought it with the HG gone so it was rebuild by myself and my Grandad so I couldnt tell you. However, the past 3 years it has passed MOT with Zero advisories so theres nothing obvious.

[lemski]

Whens the fuelling issue started. Made sure all connections are tight in fuel system.

[LeeOxley]

I couldnt tell you when it started and all hoses  are tight

[lemski]

Hmm. When I had a webber its wasnt amazing onfuel. I had twin choke 32/34

If the cars running fine. Emissions fine and you say there no leak, you could have it down jetted to allow better fuel economy.

[gazareth]

first thing I would do is check all the brakes to make sure they are not binding. then I would re-check the camshaft timing and the ignition timing. if that all checks out fine then the next step would be get it on a dyno to set the carb up properly.