Weber Carbs in -40 celsius

[So_Powerful]

I was wondering if I could have some feedback on the operation of weber carbs in temperatures ranging from -30 degree celsius and colder. Do they freeze up and stop working or what?

[Petros]

Do they freeze up and stop working or what?

That sounds about right.

The Weber has been around for a long time and was actually the factory carb for a number of cars built before emissions controls were required on the carb. They work pretty well, which is why they are still popular, but like all carbs they have their short comings. If you are ever lucky enough go examine how they were used in the production cars they had a number of "accessories" installed by the factory that you do not get with the carb. Most had either water heated manifolds or electric heaters installed under the carb. If you want to solve the cold running issues you would have to experiment with heating elements or other means of keeping the carb warm.

When fuel vaporizes in the ventrui of the carb it drops the air temp, if there is any moisture in the air it will condense into droplets. If the throttle area is below freezing it forms ice, can causes all kinds of havoc. Even EFI throttle plates are warmed usually with coolant to prevent ice formation behind the throttle. Consider even the stock 3A carb has several ways to heat the area under the carb; the electric element and the exhaust butterfly.

[splatterdog]

I do encounter harder starting when it's really cold. Haven't not started though, ever, down to at least -30f. It just takes 3-4 starts to keep going on its own. Maybe a couple more starts to break the gear oil free. One overnight ice fishing trip with the 84 was so cold, the gear oil killed the engine a few times when letting the clutch out in neutral and even made the car lurch when I finally broke it free. That was with synthetic too! Fluid drive...

Just need a good battery, and state of tune and all should be well. Block heater will help if you deal with lots of subzero temps. As far as the weber itself, just make sure the choke spring tension and high idle screw are good for your conditions. My heater/insulator plate were eliminated.