Idling 1400rpm when hot

Hi folks,

I recently replaced the fuel tank and pipes etc due to badly corroded tank and filler pipe.  The car has never let me down and always ran like a dream - until I fitted the new system.  I cleaned out all of the old rust and there isn't a block anywhere (I think).  It starts first time every time and idles ok until it has been running a while, it slowly raises to about 1400rpm. Runs fine though.

Will replacing the fuel lines have affected the running in the carb (obviously it has just wondering if this is common)?  Is there anyone in the North East that can help set up the carb - I'm pretty basic in skill level.

Thanks in advance.

Mark