-25 degrees c really that cold Mur. Like i said i don't know what temp the band works at but i have seen them on UK cars way back and i know the temp did/does not get down to -25 degrees C. Come to think of it i saw one on a low mileage UK import LHD Moke over here from up North not long ago, can't imagine driving a Moke in that teperature.

I am pretty sure it doesn't work till -25°C but you folks are welcome to find a functioning one and test it.  I'm especially keen to see if the dashpot band is able to do anything more than prevent a dashpot binding because of the tolerance at low temps. 

Keep in mind that these items were designed for fuel from 45 years ago.  I would wonder how that crapanol fuel from the flyover states would respond to these pieces if they were functioning.  If your fuel pump banjos or diaphrams didn't fail first, what would happen if you turned the ignition on, pulled the choke all the way out, waited a while, didn't have your pertronix fail because of the waiting; and then hit the starter?  Would the non gasoline fuels ignite as they pass the heater coil?

Doug i am not sure what temp the band works at but it was more for the icing up problems SU's had which was common on other BL models too. The piston inside the dashpot would just freeze in place when travelling at sustained speeds. It happened especially on the motorways and is quite a wake up call when you take your foot off the accelerator on the exit ramp and the car is still doing 70 plus mph, then you try to downshift only to have the engine screaming the red line at you, ask me how i know. It was one of the reasons also that cars had a winter and summer setting for the intake tube on the air filter.

I have seen those parts on a friend's collection of old Austin America carbs.  erhaps those parts came from Canada.

Mur, at what temperature does the band heater around the suction chamber work?  I assumed it was there to help "thin" the dashpot oil a bit until the engine warms up.  Is that correct or does it serve a different purpose?

The Canadian-type carb throat heater was more to warm the air/fuel mixture enough to reduce the fuel condensing on the throat walls until the manifold warmed up (remeber they had siamesed manifolds). When it is -20C or -20F there isn't much moisture in the air at all, so icing wasn't the issue. The band around the dashpot was to warm the shell to slightly increase the tolerance and reduce the resistance to the piston moving, again until some heat was present. It wouldn't heat the damper oil - too far from the element.

BTW carb icing is more an effect of humidity and adiabatic cooling from pressure drop beyond the venturi and throttle plate. VW air-cooled engines had an exhaust tube running up through the manifold area to provide warmth. My brother tried removing one once with the result of immediate icing... at about 80 deg F and relative humidity probably in the 80's to 90's. The engine just wouldn't run without it.

Ok de-icing makes sense. Maybe this was canadian mini. Yes icing can happen well above freezing high velocity lowert pressure under dew point. Thanks all for the info.

Carb icing is not an issue when you are starting the car.  Once the car is running it is warm enough that close to the manifold to shut the heater off.

Personally, I only experience carb icing on a mini at dawn in the summer with a strong 1380 pulling very hard down the highway.  I guess it has more to do with the fuel going through a change of state at the venturi than it has to do with cold.  If you go back to the aircraft carb icing descriptions you will see that it can occur at 20°C as long as the change of state is sufficient and there is moisture present in the air.

For this situation, a longer heater return hose wrapped around the dashpot suffices.

A cold carb will work just fine... but its a matter of "Carb Icing", rather than just a cold carb... A lot like carbarated aircraft engines, the Mini carbs (in cold climates) were susceptable to Carb Icing.  In cold humid conditions the ice will form inside the carb eventually cutting of air to the mixture.  Thats ok in a car (pull over)... but not so nice in an aircraft... In most carbed small aircraft engines we can reroute hot exhaust air to the carb to melt the ice rather than an electrical coil.  The coils on the Mini Carbs worked well.
These were pretty standard on Canadian Mini's.

None of it is a joke.  The throat heater comes on at about -25°C via a thermoswitch in the bulb of the carb spacer item, and it also powers the dashpot warmer.

In extreme cold, I would turn the ignition on and wait for a full minute before trying to start the car.  These pieces do their intended job quite well.

...on ignition  (?)

Yes heaters and in parts books. Throat heater would make sense for a diesel but not for gasoline. Collar heater has to be a joke. But car spent most of its life in Minnesota I believe so maybe believers there.  Didn't check connections so don't know if they were on timers/switches/thermostats?

Here you go

//www.somerfordmini.co.uk/eshop/index.php?main_page=product_info&cPath=328&products_id=13713

//www.somerfordmini.co.uk/eshop/index.php?main_page=product_info&cPath=328&products_id=13556

I think thats a carb heater fitted to cars here ( and maybe Switzerland )

Evaluating an early Morris 850 cc engine and noticed what appears to be a heater collar around the carb with PN AUC 8092.(1st pic) Also there is plate with another heater element behind the carb (2nd pic). Can't seem to find any info (Function/purpose) on either one other than existance in a SU parts book.