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 Post subject: Erratic idling
PostPosted: Thu Feb 15, 2018 10:14 am 
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Joined: Thu Mar 17, 2016 11:35 am
Posts: 13
Can anyone help me with an erratic idling issue? Problem is the car idles just fine sometimes and bogs down and quits at others. Usually when I come to a stop light or slow right down for a corner it will stall if I don't use accelerator. Usually but not always.
Car has new plugs, points, rebuilt carbs professionally tuned.


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 Post subject: Re: Erratic idling
PostPosted: Thu Feb 15, 2018 4:45 pm 
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Joined: Thu Dec 19, 2013 4:44 pm
Posts: 14
Hi Peter, I had a similar problem where, when I came to a stop when the engine had warmed up, the revs would drop and the car would cut out. I found that the carbs were tuned too lean and after richening them up the problem disappeared. I found that there was only about 1 to 1 1/2 flats in it. The carbs were new and supposedly tuned. Check by pulling on the choke when it happens, if the revs go back to normal the carbs are too lean. Good Luck.


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 Post subject: Re: Erratic idling
PostPosted: Thu Feb 15, 2018 7:09 pm 
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Joined: Thu Dec 19, 2013 3:40 pm
Posts: 131
Peter
The term 'professionally tuned' always makes me smile. Yes, yours may be just that but there are fewer people around today that really know what they are doing with an old simple car.
As suggested, it sounds like a lean mixture. Get the car up to temp, pull the air cleaners off and then use a thin tool to lift the dash pot about1/4" and the engine should remain at about the same RPM. If the RPM rises then it is rich. If it drops then it is lean. Turn the adjusting nut about two flats at a time to start with then one or less once you get close. Give the engine 1 or 2 seconds run at about 1500-2000RPM between adjustments to clear the plugs.
The ignition may also be retarded, check that first.


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 Post subject: Re: Erratic idling
PostPosted: Fri Feb 16, 2018 10:20 am 
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Joined: Fri Dec 20, 2013 10:30 am
Posts: 29
I had this problem long long time ago after fitting new carbs.
Was solved by resetting the float level.


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 Post subject: Re: Erratic idling
PostPosted: Fri Feb 16, 2018 5:54 pm 
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Joined: Wed Dec 18, 2013 5:05 pm
Posts: 240
Hi Peter,

Like Aladdin I'm not sure what professionally tuned might have entailed.

I have found that it is often pointless tuning individual items. e.g. just doing the mixtures. There have been a number of times trying to fix a rough idle I have assumed things were right and have gone straight to adjusting the mixtures. After a lot of stuffing around with little success and getting the mixtures way out I have gone back and done it properly.

Personal experience, I tune it in the following sequence:

- tappets first,
- the points if you have them,
- the timing (although I redo it at the end during a road test),
- plugs,
- carbie balance,
- mixtures.

If you get all this right and it still won't perform properly start replacing items like plugs, leads, points, condensor, coil one at a time to see if it fixes the problem. I usually start at the cheapest bit first and if it doesn't make any difference keep the bit I took out as a spare.

Another thing out of left field, make sure your generator/alternator cables are tight and charging properly. I had a charging failure today about 20kms from home. The idle was noticeably better when I had repaired the problem at home (a broken generator charging cable).


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 Post subject: Re: Erratic idling
PostPosted: Sat Feb 24, 2018 10:38 am 
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Joined: Thu Dec 19, 2013 9:35 am
Posts: 65
There are sooo many reasons but a drop of oil on the Carb spindles when running will also indicate if they are worn enough to give to too much air so lean run and also unpredictable idle, particularly when hot.
Just another one to add to the check list but mostly for old carbies rather than new.
Also regularly oil all the Throttle linkages as they can and do cause unpredictable idle.
Rob


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 Post subject: Re: Erratic idling
PostPosted: Thu Mar 15, 2018 10:58 pm 
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Joined: Fri Dec 20, 2013 7:13 pm
Posts: 36
Hi Peter,
have you solved your idling problems? One of the reasons you can have inconsistency is if the springs returning the main jets after using the choke, are not strong enough and the jets don't return right home . To test this, put fingers under the jet and if it can move up, the spring needs to be stronger.
Also , a problem I was having was the adjustment to have both jets move down equally by adjusting the linkage between the levers so when in use, the jets equally move down. It doesn't take long to oil up two plugs if unbalanced. Rusty


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