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black plugs at tickover

Posted: Sun Jul 01, 2012 10:02 pm
by monty55
After a year of running problems, I recently stripped and cleaned the carb. Its now running great – tan coloured plugs, pulling cleanly etc. Except – the plugs turn black if it is left to tick over.

I’ve also noticed the fuel pump ticks every 15 secs with just the ignition on, so I checked the float level, thinking this could lead to it running rich at tickover.

At about 6.5mm from the float to the float lid, the float touches the needle and blocks the flow (tested by me blowing into it!). The float can then be pushed further down until the edge of the float touches the float lid.
Everything it clean and nothing is sticking. The float cannot be adjusted – there is no lever. I’m guessing that the float needs to be more than touching the needle to stop the fuel flowing from the pump.
The fuel in the float chamber is about ½ full after it has been ticking away with just the ignition on.
Does this sound OK - or do I need to be checking something else for the plug problem?

Thanks for any advice
paul

Re: black plugs at tickover

Posted: Sun Jul 01, 2012 10:39 pm
by bmcecosse
Just adjust the idle mixture! 'Tan' plugs are a bit rich - light beige will be better!

Re: black plugs at tickover

Posted: Mon Jul 02, 2012 12:43 am
by lambrettalad
slightly yellow is perfect,yours seem pretty good on non tick over but how much time do you spend on tick over?

Re: black plugs at tickover

Posted: Tue Jul 03, 2012 7:44 pm
by monty55
I was letting the car tick over on the drive after adjusting the mixture, to see if it improved things...

I'll adjust the mixture a tiny bit at a time - I'm happy it is running OK for the first time in a while

Re: black plugs at tickover

Posted: Sat Jul 07, 2012 6:56 am
by monty55
bmcecosse wrote:Just adjust the idle mixture! 'Tan' plugs are a bit rich - light beige will be better!
great :D
adjusted by 1 flat - pump now ticking normally.
I think the carb has always been set too rich - over 15 years now :oops:
The plugs are also lighter in colour, and its still running really well.

thanks for the advice
paul

Re: black plugs at tickover

Posted: Sat Jul 07, 2012 11:02 am
by bmcecosse
1 flat? I'm amazed that makes any significant difference.....but if it's working well for you - well done !