Hi
Just a quick question, I am sure the experts on here can answer easily.
Which way do you turn the nut at the bottom of the carb to weaken the mixture, my car will start on a cold morning without the choke, but I do need to pull it out when pulling away for the first few minutes. Other than that the car runs fine, starts first time warm or cold, but I just have a feeling it is running rich as it hunts a bit at idle speed.
Thanks for any replies.
Looking down from above - you turn the nut anti-clock to weaken the mix. But I suggest you have a look at the spark plugs after a run (not after idling!) - what colour are they?
Hi bmcecosse
Went on a twenty mile run then took the plugs out.
They all look the same, I will see if this photo works.
Is this the right way to respond to your question or do I need to send you an answer directly, sorry if that's a stupid question but I am new to message boards, we didn't have the Internet when I had my previous two Minors!![frame][/frame]
Perfect picture - and clearly shows that your car is running very WEAK ! The plugs should be 'light beige' after a good run - that picture appears to be 'white' ? Is that the case to your eye? Running like that may give best economy - but at the loss of some performance, and at a risk of perhaps burning the pistons. It's up to you - but I would want to turn the nut a flat or two clockwise - to richen the mixture slightly. And -absolutely correct to come back on the forum - this way the whole community gets to see your problem and to offer the best advice we can come up with. And of course - we all learn from the problems and answers that run on the forum. It's a 'collective intelligence' - and we all learn something new every day!
Hi
Maybe it wasn't the best picture after all, just been back to have a second look and the ceramic?? Cone in the centre of the plug is a light beige colour, I probably would have described it as a tan colour, it just doesn't show in the photo.
I had weakened it slightly before the run and she did seem a little more responsive on the throttle, and idled a little faster than before, I am probably being picky but am enjoying fiddling and getting to know the car!
Still does not answer the problem of hunting at idle which is probably adjustment of the fast idle screw.
Look for two screws with springs coiled around them. One screws down against a stop and controls the tickover speed, the other controls the idle speed with the choke out. Pull the choke out and watch which screw moves, this is the fast idle screw. Wind it up so that there is a gap between the bottom of the screw and the choke cam. With the engine at running temperature adjust the tickover screw to give the correct idle speed then wind the fast idle screw back down so that the screw just touches the choke cam. When you pull the choke out it will speed the engine to give the correct running for the mixture.
Last edited by mike.perry on Sun Jan 19, 2014 11:19 pm, edited 2 times in total.
The screws are only for speed.... Your float valve may be leaking and allowing excess fuel to flow through at idle - hence it starts without choke, and 'hunts' when idling. But when running along - the fuel is required, and is burned - so the mixture is fine = correct colour plugs. Test here is - switch on the Ign and listen to the fuel pump - it should click a few times - then STOP - just maybe an odd click after say 20 seconds... If it clicks steadily/every few seconds - then the valve is leaking.
The pump clicks a few times then stops, this is the only time I hear the pump, I remember on my other Minors the pump seemed louder and more frequent. The only time I have heard the pump when driving was when stuck in a traffic jam. Seem to remember reading somewhere unleaded evaporates quicker than the old leaded petrol, and I seem to remember fitting a heat shield to the float chamber of my old series2. The screws seem to be OK, as you pull the choke lever the cam opens the throttle. After I weakened the mixture the idle speed went up so I have reduced it a touch and it is idling fine so I think I'll stop fiddling with it now Thanks for all the advice.
How about the carb needle? I believe I have the "M" needle in my 948. Is that correct for the engine? Which needles are a step leaner and richer if I want to tinker?
David
