dulbinpilot
 

I STAND CORRECTED, I think i will stick to turbine's and keep my mouth shut

Laugh out loud!:D :D

Though you were going to try and confuse me by bringing in constant speed props!! ;)

I'll get my difference training soon!!

FWIW, for constant-speed props, the indication of carb icing (in the first instance) is a drop in manifold pressure. This again will behave in the same way as RPM in dublinpilot's description of fixed-pitch ops.

I have experienced carb icing in my 1977 Alfa Spider which has twin Dellorto carburettors, and am pretty sure that I had it on a Triumph Vitesse I used to own which had two Strombergs. The Alfa does have a knob to alter the direction of the air intake but I usually forget to move this.

This is really a sneaky way of getting an ad past Paul: anyone wanna buy my lovely Alfa? Goes like the clappers and hardly ever gets carb ice really. Very pretty and, er, red.

All PPLs should drive old cars because we appreciate machines which, despite being impractical, thirsty, noisy and smelly and requiring to be twiddled with by men with spanners and inventive approaches to invoicing are nonetheless highly entertaining.

Carb icing can occur on any petrol engine, as it is caused by 2 cooling effects, firstly as the air speeds up through the venturi its pressure drops and this causes cooling secondly as the fuel is atomised it is cooled by evaporative cooling. The way this is avoided in modern car and bike engines is to run with permenent carb heat supplied by heating the inlet manifold with coolant from the liquid cooling system.

I would be interested FNG, except I have already got a nice red 1976 Alfa Romeo Spider 2000, that is not for sale :D

I have never had carb icing on this Alfa, but then I only drive it in nice weather, when I can pose with the lid down :cool:

So, its not been out of the garage much this summer. :(

Once had a Fiat Panda and if ever a car needed Carb heat this was the one! Was forever losing power on the climb.

Fiat panda?

Loosing power in climb?

Come on, you're driving a Fiat!!!

Has nothing to do with carburator icing :D

Most ´modern´ carb equipped cars (build in the late 80´s) had automatic carb heat, mostly a flap actuated by a vacuum driven diaphragm actuator switching from free air intake to an intake close to the exhaust muffler or in many cases to the exhaust muffler heat shield. Vacuum actuation automatically worked more with low manifold presure (more prone to icing) and less at full throttle. An additional temperature sesitive valve vents the vacuum line at intake air temps above 30 °C, this valve is installed in the air filter housing, closely in front of the carb for most japanese cars.
On older cars (i know from a 60´s Renault 4) you have to switch manually from ´summer´to ´winter´.
The ´winter´ setting (permanent carb heat) costs a little performance and causes slightly more fuel consumption. This is compensated by the higher air density in winter.
In Airplanes we always need full power, so permanent carb heat is no good idea.

I know Carb icing frequently on the Volkswagen Beetle (the old one with these cheap rubbish paper type air hoses that always broke when getting older and let in fresh air in the hot air duct...) which results in total stopping of the engine at idle. No problem while driving with more power.
On the 1987 Honda Civic the effect of carb icing was even more interresting, it happened frequently on cold, misty mornings at slightly above freezing point. This high tech carb had lots of valves, jets and pneumatic actuators for best air fuel mixture at all power settings, unfortunately some of the compensating air jets were affected by icing, causing the second stage throttle valve actuator to open when idle, which results in quite interresting characteristics. It always started after about one minute and went normal after just 2 or 3 minutes when the exhaust was hot enough to preheat the intake air.
This also made the choke ineffective, which only worked on the first stage of the carb, so the engine was running at 2500 rpm idle, but had no real response to the throttle when you wanted the engine to speed up.

Good old days, when you didn´t need a degree in electronics to make your car run again ...:D

Used to have an Escort Mk3 which progressively lost power in the middle of the Scottish Highlands during a whiteout at 2230 on a Sunday evening until coughing to a halt (somewhere around 10 miles from the nearest phone box and this was before the days of mobile phones - there'd have been no signal anyway!!). Thought that it was wet plug leads, so sprayed WD40 everywhere - lo and behold it started! Went to dealers at next service and asked them to change plug leads (it was a company car!) - they did so, but said there was nothing wrong with them. Went through details of what had happened and they diagnosed carb icing (which had cleared during the stationary bit whilst I sprayed the WD40).

Back to flying - the more experienced amongst you may now yawn and turn away ;) . I also hold a Bruneian PPL (from when I worked out there for a few months). Despite average daily temps of 30-35 deg C with up to 98% RH, one of the major threats is carb icing (worse than UK). I know it's in Safety Sense, etc, but the average guy (or guyess!) wouldn't normally think of carb icing in that temperature!

Distaff Beanounter, you are lucky to have a garage for your Alfa. Alas, I now have no garage for mine, which is the main reason for selling the car. I fear that left outside it will go funny as quickly as an Auster or Cub parked in a field (except that, unlike an Auster or Cub, it is unlikely to have its wings eaten by cows)