Carburettor overflow

[Joseph Dobson]

I’m afraid I seem to be dominating the technical forum at the moment but as I am new to Tractions there are certain aspects I am uncertain of.  My latest problem is that after a run and the engine is hot, and the carburettor for that matter, petrol issues forth from the overflow under the carb.  Is this a normal Traction foible or is there something more seriously wrong.  At present I seem to be consuming fuel at a rate faster than I anticipated and certainly more than my HY van.  Any suggestions ?  Thank you to all of you who have replied to my earlier questions, those problems are now sorted.

[BernieParticipant]

Joseph,

It is not uncommon for a little fuel to drain out of the overflow – especially if the throttle has been depressed after the engine has stopped running – but your “issues forth” suggests more than that.

I wonder if either the carb float level is set too high or the fuel valve is sticking, allowing fuel to escape while the system remains pressurised between the carb and pump.  If you prime the fuel pump manually (without the engine running) either of those faults is likely to cause fuel to overflow from the drain pipe once the carb fills up – even on a cold engine.

And a word of caution …. It may be obvious but there should be a set in the overflow pipe to ensure it does not dump fuel directly onto the starter motor.

B…..

[Joseph Dobson]

Thank you Bernie.  I have substituted the loose brass float in the new carb I bought and replaced it with the old plastic float that is attached to the lever.  This seems to have cured the problem although I ave not taken it out on a long run so that everything gets really hot.  I have also replaced the main jet with a smaller size and increased the air correction jet size both without detriment to the running of the engine.  In fact the engine will now increase revs without hesitation.

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