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+--- Thread: Hot petrol (/showthread.php?tid=4493)
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RE: Hot petrol - Mike Costigan - 12-06-2020
This thread highlights two divergent problems: carburettor icing and the original topic, hot petrol.
If your car is suffering from the former and has the early updraft carb, it may be that you are missing the hot-spot copper washer fitted to the top of the inlet manifold (BE23 in the parts book).
BE23.JPG (Size: 59.25 KB / Downloads: 97)
This is often omitted but if so then icing in the inlet manifold is almost inevitable. If you are running a car with a horizontal carb and manifold and are suffering from icing, then try wrapping some copper wire tightly round the inlet and exhaust manifold to provide some heat transfer.
Unfortunately modern fuel seems to be more susceptible to vapourisation, and airlocks in the fuel pipe and boiling in the float chamber seem to be common place these days, although so far I have not suffered any problems with my car. It's worth checking that your fuel pipe does not have any vertical coils in the system as this will encourage air-locks. Boiling in the float chamber is down to excessive under-bonnet temperatures - if you have a Ruby then open the bonnet vents; on earlier cars it may be a case of propping the bonnet open or even removing the bonnet altogether!
RE: Hot petrol - andrew34ruby - 12-06-2020
Mike, the question when I started this thread was...
"why do the vast majority of cars blow the air heated by the radiator straight onto the engine?"
It seems an odd way for most cars to be designed and it hasn't changed today. But maybe it helps to reduce carburettor icing, maybe petrol vaporisation has never been a problem worth fixing, and maybe it doesn't matter.
RE: Hot petrol - AustinWood - 12-06-2020
I have never had petrol problems with my RK fabric saloon. The exhaust downpipe id lagged and there is an aluminium shield below the updraught carburetor.
On our trip down to Masham for one of Malcolm's runs we went a circuitous route and climbed over the highest paved road in England in very hot weather. At the top we stopped to enjoy the view. The car was a bit reluctant to start and ran unevenly for a short while and was then back to normal. The petrol in the carburetor was boiling. There has never been any problem while driving. The car is in regular use in all weathers.