Jet adjustment

[Marc S]

Hi all,

A very newbie question I'm afraid...


Trying to set up the carb, and it seems to run ok with the jet adjusted 3 or 4 flats from tight home...but the idle screw is backed right off.
I'm sure I remember from days gone by, starting at 12 flats from tight...or am I dreaming this???

MoT is booked for first thing in the morning, need to drive into town, and I don't want to do any harm if it's lean...

[bmcecosse]

The 'number of flats' is just a guessing game. Adjust till you get the smoothest idle - then check by lifting the piston slightly. If the idle is too high then the cable is probably too tight - or the return spring not tight enough.

[Marc S]

the return spring is ok and cable has a little slack, I'm just surprised if it's idling ok with it all backed right off.

It's ticking over smoothly enough, I did undo it a bit, but it did seem to be running rich, and a bit lumpy, so I leaned it in again.

I've got very little time in the morning, hopefully it'll be ok...I can stick it on the gas analyser at the garage - what sort of figures should I expect to see?

[les]

The 12 flats business you mention was a starting point, I also remember it from way back!

[dalebrignall]

that wont be far out the plugs should be a biscuit colour as long as there are no clouds of smoke the car will pass

[Marc S]

He passed!

Carb wasn't far out, set it a tad richer to be on the cautious side, but it was ok.

[bmcecosse]

They don't test emissions on a Minor anyway - just a 'visual' check - ie no blue /black smoke . Welldone on the pass. If it's still idling fast then air must be getting in other than through the carb throttle.

[Marc S]

No, I know they don't test the emissions, as it's pre 1974, but he put it on the analyser so I could check the set up, and I adjusted it half a flat while I was there

It's not idling fast, I just think something is probably wrong if it's idling right, but with the adjustment screw backed right off to nothing...

I will have a better look when I've got more time, maybe strip the carb for a service