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Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 11:28 am
by 67-2door
My 1968 minor has two pipes from the top of the float chamber, one obviously is the feed pipe from the pump, the other just hangs down and vents into fresh air down by the sump. Is this correct or should it be connected to something? My friends 1967 minor doesn't have this 2nd pipe at all.
My other question concerns the air intake to the air filter, mine is almost touching the exhaust manifold so must be drawing in very hot air, it doesn't seem possible to turn the airfilter housing round without physically taking it off & repositioning it to face forward and then it would need a longer breather pipe to reach the rocker cover. Is it meant to be turned round to a summer position or just left by the exhaust manifold all year round?
Forgive my ignorance I'm still new to Minors.
Neil.
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 12:54 pm
by mike.perry
The float chamber sounds like one for a twin carb set, a supply from the pump and a feed to the other carb. You should be able to remove the air filter and turn it around to face the radiator in the summer.
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 1:05 pm
by Stig
The second pipe on the float chamber sounds like an overflow so I'd leave it as is. Is it directly underneath the one from the pump? If it's at the same level and at 90 degrees than it'll be the fuel feed for a second carb and must be blocked.
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 3:54 pm
by bmcecosse
Is the second pipe coming from the top of the float chamber - or is it coming from the side of the carb ? A picture would help!! You should be able to lift the intake pipe away from the manifold so it gets 'cooler' air - without turning it right round.
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 5:47 pm
by 67-2door
The two pipes exit the top of the float chamber parrallel, both pointing toward the front of the engine, the left one is slightly higher and goes to the fuel pump, the right hand pipe just dangles. The air filter wont rotate more than a few degrees because the float chamber pipes are in the way.[frame]

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Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 6:11 pm
by PSL184
I guess it must be from a twin carb setup as you would normally only have one pipe feeding the top of the float chamber from the pump. Maybe best to blank the "spare" one off.....
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 9:00 pm
by bmcecosse
No - let it breathe! Can you not twist the filter casing clockwise enough to move the nozzle away from the exhaust ? Otherwise - turn it right round - and use a longer hose to the rocker breather ?
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 10:30 pm
by 67-2door
It had occured to me to turn it right round & fit a longer breather pipe.
You think it would be better not to block the 2nd pipe off & to let it breath then? It does seem to run ok like that.
On a slightly different note, do Minors normally need choke to start from cold? Mine starts from stone cold with no choke without touching the accelerator, is mine running a bit rich or is that normal? (again it runs ok with no obvious signs of running rich).
Neil.
Re: Carb breather & air filter questions.
Posted: Fri Jun 11, 2010 10:38 pm
by bmcecosse
There's no way mine will start without choke! Let it breathe - it's a top from a later Mini carb. Is the float bowl sitting dead vertical ?
Re: Carb breather & air filter questions.
Posted: Sat Jun 12, 2010 1:12 pm
by 67-2door
The float bowl certainly looks to be sitting vertical.
I wonder why mines running rich? Cant be too far out because it's not putting any black smoke out the exhaust.
Re: Carb breather & air filter questions.
Posted: Sat Jun 12, 2010 3:00 pm
by bmcecosse
Check the plug colour after a good run.
Re: Carb breather & air filter questions.
Posted: Sun Jun 13, 2010 5:31 pm
by 67-2door
Changed the plugs this afternoon and they dont look a bad colour, a little black & sooty around the outer edge but the centre & electrodes are a nice chocolatey brown colour. I guess from that the mixtures not too far out, dont know why it starts from stone cold with no choke or throttle. Is it idle mixture adjusted seperately (ie, rich at idle but correct mixture higher in the rev range)?
Re: Carb breather & air filter questions.
Posted: Sun Jun 13, 2010 7:59 pm
by bmcecosse
Choc/brown is RICH(ish). Should be light beige for best economy.
Re: Carb breather & air filter questions.
Posted: Sun Jun 13, 2010 9:43 pm
by mike.perry
I saw a pair of H1carbs yesterday and they were fitted with float chamber overflow pipes.
Re: Carb breather & air filter questions.
Posted: Sun Jun 13, 2010 10:31 pm
by bmcecosse
Indeed they are - I have several!