7 replies to this topic

[cap'n crunch]

It would not be autumn/winter without my carbs freezing up. Last year it was Twin HS2 freezing up and making my car undrivable and stall. This year I have a 28/36 weber.

And yesterday when it was the first particularly cold day of they year, yep thats right, they froze. Now because they are operated differently to SU's even though the outside of the carb body was white with ice it did not effect the cars performance. So all is good, and should the weber Ice really badly and effect performance then i have got a heated inlet manifold i could use.

But my question is this, why is it whatever carb i use they ice up? yet it would appear i am the only mini owner who has this problem?? so i am curious as to why on earth am I the only one to suffer from carb icing

[Nelson92]

i got a paint brush and some heavy grease and painted the sides of mine where ever anything moves.
it may get cold and firm up but it's not gonna freeze in the uk. [touch wood]
if it does freeze can't you just blast it with windshield de-icer and start the car?

[Ivor Badger]

Carb icing is a combination of air temperature and humidity. With the amount of rain recently, we have high moisture content in the air with a recent cold spell. Freezing fog is the worst. Simply add some form of warm air feed to the carb air intake, like draw the air over the exhaust manifold which is the norm. When the petrol evaporates in the carb venturi, it requires heat to vaporise the petrol and this drops the air temperature and the high moisture content in the incoming air freezes and forms the ice. Since it is not a moving part problem, no amount of lubrication will cure it.

[Nelson92]

Now because they are operated differently to SU's even though the outside of the carb body was white with ice it did not effect the cars performance.

i was referring to this bit about the outside of the carb body, mainly the choke and throttle cables and even idle screw.
if they've got a good coating of gease they won't freeze solid or get ice forming on them.
sorry if i've missed the point.

[cap'n crunch]

i was referring to this bit about the outside of the carb body, mainly the choke and throttle cables and even idle screw.
if they've got a good coating of gease they won't freeze solid or get ice forming on them.
sorry if i've missed the point.

Yes and no. Yes there would be no ice on the outside but as Ivor Badger said it ices up due to drop in air temperature inside the carb which freezes up the inside. A warm air feed is both very tricky to implement as it is a downdraft carb and the air filter just scrapes under the bonnet, and getting "warm" air is nigh on impossible.

But my question is why has no one else been affected by this? most of us use carbs so what is different about my setup that I am effected but no one else?

[jkjaxor]

can you not heat the manifold, somhow? or maybe have an "induction kit" to the outside of the radiator? might get warmer air from there?
jack

[Ivor Badger]

i was referring to this bit about the outside of the carb body, mainly the choke and throttle cables and even idle screw.
if they've got a good coating of gease they won't freeze solid or get ice forming on them.
sorry if i've missed the point.

Yes and no. Yes there would be no ice on the outside but as Ivor Badger said it ices up due to drop in air temperature inside the carb which freezes up the inside. A warm air feed is both very tricky to implement as it is a downdraft carb and the air filter just scrapes under the bonnet, and getting "warm" air is nigh on impossible.

But my question is why has no one else been affected by this? most of us use carbs so what is different about my setup that I am effected but no one else?

Where is your carb air intake?

[ECG317W]

Why would having a heated manifold help?

The icing is occuring inside the carb, which is before the manifold, so a heated manifold won't do anything other than slightly warm up the charge after it has passed through the very restrictive (iced up) carb.