Fuel consumption, CO


(Paul Wigton) #41

Just about a sure sign the carbs are running too rich.


(Frank Andersen) #42

**
Champion is my favourite, Nick…:slight_smile:

But you will not notice much change in fuel consumption if the carbs are the culprits…

Frank
xj6 85 Sov Europe (UK/NZ)
**


(nickhill) #43

Hello everyone,

Back from the garage following ignition timing and carb overhaul.

Immediate result is no more smelly exhaust and fuel consumption now about 20mpg at 50-70 mph. Which feels more like what it should be.

Thanks for your help.

Nick Hill

XJC 4.2 (1975) Canadian spec
Paris


(Frank Andersen) #44

**
That’s about as good as it gets, Nick - unless you are a fanatic…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
**


(nickhill) #45

Forgot to mention the entertaining CO stats:

Legal limit in France: 4.5%
Before carb overhaul: 8.86% (!!)
After carb overhaul: 1.36%


(Jochen Glöckner) #46

Nick,

1.36 % CO seems a bit too lean for my taste - I’d rather aim for 3 % and you even stand a chance that your mileage increases further because the richer tuning gives more low-down torque and reduces revs.

I envy you for the loss of the smelly exhaust!

Best wishes

Jochen

75 XJ6L 4.2 auto (UK spec)


(Frank Andersen) #47

**
I agree with Jochen, Nick - carbs are set fat to ensure consistent performance through load and rev range.

Principally; lean running requires more pedal for the same output - not necessarily good for mileage. But if your engine behaves, no harm done…

Frank
xj6 85 Sov Europe (UK/NZ)
**