Fuel overflow pipes

[richardthestag]

Afaiaa the vent and overflow pipes are separate items.
The o.p. Was asking about overflow pipes.

The overflow pipes are perhaps an acknowledgement that strombergs on the stag are installed at a jaunty angle…. Above the recommended angle (perhaps)

The float chamber definitely wasn’t originally designed to be installed at the angle it is in a stag.

There… I’ve said it!

Glad you mentioned it Julian

Ah yes, you are correct about the two vents, one is managed by the jiggle pin which exits via the airfilter elbow and into the back of the air filter. The other is managed by the err.... jiggle pin and via pipework and down the front of the engine.

Here is a nice cutaway from a 1973 edition of Triumph's Emission control systems document, Because it is for the 'Merican market, mention is made of the charcoal filters et al. Position A is the vent pipe that goes down the front of the engine.
vent.jpg

Strange how no publication, be it Official ROM, Haynes nor Stromberg documentation ever thought to call them overflow.

Regarding your concerns about the angle of the installation, why do you think that the float level is adjustable and also why are the vent pipes at the highest point on the carb body when installed?

Not yet experienced a stromberg CD (nor SU HIF) on Rover v8 nor Triumph v8 overflow when float level is set correctly, a decent float chamber needle valve is installed and the correct pressure is delivered to it.

Richard

[jbuckl]

Right the overflows are actually supposed to only ever be vents then. My bad.

When they overflow it’s only because the needle valve has stuck?

Have had the needle valves stick too many times.

my car is running with about 2.4 psi

[richardthestag]

indeed, burlen needle valves have yet to fail me. rimmers do a needle valve with a small filter on the pump side. pricey but extra insurance I guess.

replace flexi fuel lines and filters if your needle valves are failing regularly.

carbs of any type only overflow when there is something wrong with them.

fix the issue rather than working around it.

you wouldn't work around a temp gauge in the red, nor a flat tyre. you would find root cause and fix it