TR6 TR6 Gas Leak From Front Carb

[mickjj]

Can there be any other reason for gas to leak out of the front carb other than the float and needle valve? I have a 1969 TR6 which when I brought it home and parked it nose first on my sloped driveway gas was pouring out of the front carb. Off they came and I got the Zenith service kits and a different pair of carbs from a 71 and replaced all the jets, gaskets,O rings etc set the float valve to the correct setting and put them on the car. It fired up first time and though rough was tunable. Well you've guessed it the gas is leaking from the front carb again so I retightened all the screws but to no avail. Can there be something else that is causing this as it seems strange that the same thing has happened with separate carbs

 

[poolboy]

The principle is pretty simple..The fuel pump supplies gas to the float chamber. As the volumn of gas increase, the floats rise accordingly until they rise high enough to shut off the float chamber needle valve.
I've had problems with needle valves right out of the package and I've had what appeared to be good suddenly act up. Some say the flexible fuel line sectioms between the pump and the carbs deterioate inside because of the ethanol content, the debris affecting the function of the needle valve
Some needle valves just cannot withstand the combination of residual fuel presure from the pump or the hydrostatic head from the height of the fuel tank.
I suppose a float could also be to blame if it took in gas and lost bouyancy.
Too much fuel pressure to begin with..maybe.
And if the needle valves were replaced with the Grose Jets, then that's suspicious.
Those are the only scenarios I can come up with..

 

[glemon]

Can you tell where it is leaking from? Gas dries pretty fast, so another start up and close inspection should give additional clues.

 

[JimTR4]

You don't say where the leak actually is but I had a leak from the base of my front ZS carb on my TR4. It turned out to be the o-rings that seal the jet screw housing. They had deteriorated over time. Might be worth a check.

 

[pdplot]

Rap the float chamber with a screwdriver handle a few times. I had a leaking front carb last year and that was the cure. Hasn't leaked since.

 

[justin_mercier]

Rap the float chamber with a screwdriver handle a few times. I had a leaking front carb last year and that was the cure. Hasn't leaked since.

I had the exact same when I first fired my engine. I had lots of gas dripping out of the front carb, and then pdplot told me to hit it with a screwdriver, I did so, and it all went away and has been fine since =D (of course i'm still not quite on the road, but i'm really darned close !)