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Austinsevenfriends
Fuel evaporation AD tourer - Printable Version

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Pages: 1 2

Fuel evaporation AD tourer - Derek Sheldon - 31-05-2020

ok it’s been hot but my fuel been evaporating like mad. The exhaust is above the wind baffle and only 2” below the carb. What precautions have other owners used to overcome this problem.

RE: Fuel evaporation AD tourer - Ian McGowan - 31-05-2020

Bandage the entire exhaust pipe within the engine bay with the modern equivalent of asbestos bandage (I think mine is fibreglass based).
Also ensure that the carb is thermally isolated from the combined manifold - insulating spacer.

RE: Fuel evaporation AD tourer - Derek Sheldon - 31-05-2020

Thanks Ian

RE: Fuel evaporation AD tourer - bob46320 - 31-05-2020

Change to 98 fuel apparently it doesn't evaporate so badly. One of the problems is that your front tank is being heated by the engine. I have thought for putting insulating material around the tank of My RN, but it wouldn't look so good !
We get high 30s here and local guys say that I should install an insulated Flexi fuel pipe. I do have a 4 blade fan and have insulated the exhaust pipe with black fibreglass stuff (Awfull stuff to get on your body - itch for a couple of days) - but it still doesn't work on long hot hill climbs - even wrapped water soaked rag around the fuel pipe - best get me home was to remove the bonnet and put it on the back set.

RE: Fuel evaporation AD tourer - Dave Mann - 31-05-2020

With 3 RN saloons two without the wind baffle and one with, I only experienced fuel vapourisation on the car with the wind baffle so it was removed which solved the problem

RE: Fuel evaporation AD tourer - David.H - 01-06-2020

Is the "wind baffle " the curved steel panel under the carburettor?

RE: Fuel evaporation AD tourer - Dave Mann - 01-06-2020

    I've not heard it referred to as a wind baffle before but from Derek's description it can only be that plate under the exhaust and carburettor, it stops the carburettor icing up. Presumably Austin's knew something because it was altered to go over the exhaust on the RP. The one car with it fitted got so hot that when I stopped I could hear bubbling not from the radiator but from the carburettor float chamber, the plate was promptly removed.

RE: Fuel evaporation AD tourer - Rogerchummy - 01-06-2020

I too had terrible problems with fuel evaporation and vapour locking on my 1927 Chummy. So I wrapped the exhaust pipe below the carb in insulation AND made a simple heat shield out of thin aluminium sheet. It worked a treat - no more problems with vapour locking and the carb and heat shield are barely warm even after a long run.

You'll see from the photo that I have also added a vapour vent to the fuel line as I was told that modern fuels release more vapour than the old ones which can cause problems.

RE: Fuel evaporation AD tourer - Robert Leigh - 01-06-2020

Excuse my ignorance but how do you fit a 'vapour vent', and I don't see a photo.

RE: Fuel evaporation AD tourer - Mike Costigan - 01-06-2020

I wonder whether some blocks and heads have smaller water passages than others (I assume people suffering problems have checked for furred-up waterways)? I was out in my Seven yesterday (24°C with little wind) and experienced no signs of overheating or fuel vapourisation ... and only realised when I put the car away afterwards that I still had the radiator half-blanked off fro the winter.