DamBuster

Hoping for some help, just took my 1983 FB out for a spin, the weather is quite cold, got about 2 miles out and I just lost all power, no response from the engine at all, had to pull over, took off the air filter and had a look inside the carburettor as it felt like loss of fuel. Found one pair of jets were frozen solid (see photo, they had defrosted slightly by the time I got my camera out).
Any ideas why this might be happening and how I can prevent this happening again?
I waited for about 10 minutes for them to defrost, the car struggled to restart but did so, and I drove home easily, by which time the engine was nice and warm.
Thanks in advance for any help received!!

diabolical1

iTrader: (3)

WOW! while i know it can happen to any carburetor, i've NEVER seen it happen to a Nikki. my Dell'Orto used to ice over pretty fiercely, but it was just something i learned to deal with in the wintertime.

i'll see if i can dig something up, but i really don't know what there is to do about it since you don't control the humidity in the atmosphere.

gerald m

Does your air intake have a heat riser from the exhaust manifold to the air filter housing ? What happens is the moisture in the air freezes onto the jets and also freezes around the throttle plates causing the little engine to run like **** .. The cold air with the wind chill is very extreme going through the air cleaner if there is no warm air coming off the exhaust manifold to the air filter housing this will happen . sometimes for the throttle plates a little methyl hydrate in the gas tank will help but up on top where the jets are as far as I know the only cure is warm air coming off the exhaust manifold .. This is a common occurrence in Saskatchewan with carbed engines in the winter . Just a guess but I would say that on a -20 day the wind chill going through the intake is -40 or more and that without any heat will cause frost to form on anybody's pumpkin .. Gerald m.
Fuel injected engines don't have this problem as far as I know just carbed engines

Vicoor

Under certain atmospheric conditions (cold and higher relative humidity), the presure drop as the air enters the throttle will cause ice to form.

This is the same phenomenon that happens to airplane wings.

Carbureted engines should have a hose that picks up heat from the exhaust and delivers it to the air cleaner housing when the intake temp is blow a certain point. without this warming you can expect this condition to occur when the conditions are right (or wrong if you want to look at it that way)

Fuel injected engines can also experience this icing. It usually results in the throttle sticking open. Thats why they have coolant circulating through the throttle housing to prevent this.


Victor

DamBuster

Thanks for your replies guys, I don't think there is anything coming from the exhaust up to the air intake but I will check tomorrow, I don't want to be in a situation where I can only drive the car 6 months of the year!! (Actually given our current weather, it may only be 3 months or so!!).

gerald m

There should be something there but could have been screwed and thrown away. shoot us a few clear pics of the air cleaner and manifold area . If there is nothing there and this is a persistent problem It wouldn't be that hard to make something to do the job.

I don't know if maybe where they were intended to be sold might have something to do with weather they have cold weather packages . Anything that I've seen that was made in the 80s and sold in this part of the country had cold weather packages .

I will dig around a bit and see what I can find out . Gerald m.

gerald m

I have done a few searches there is just to much info to post .If you do a search for HEAT RISER you will find all sorts of info on the subject . Basically all a heat riser is , a 2 inch or so flexible hose coming from the exhaust manifold up to the snorkel of the air cleaner , some have a manual control so they can be closed off in the summer to prevent to much hot air entering the little engines and some are vacuum operated many different makes and models of vehicles have this ( not just Mazda rotaries ) you could easily adapt most any make to work for you just be a bit inventive . The heat riser might not fix the problem 100% but will for sure help . Good luck let us know how things work out for you ,, Gerald m.

DamBuster

Thanks for the feedback, I had a look today, the lower feed pipe into the air filter housing which is supposed to come from the exhaust manifold is missing..... So irrespective of the position of the bi-metal controlled flapper in the filter housing, it draws ambient air from the engine compartment. Going to have to either make some mods by tapping into the exhaust to provide warm air or only take the car out on warm days!!