prawnabie
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| posted on 7/7/10 at 08:02 PM |
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DCOE overfuelling at idle
Hi guys
Can anyone shed any light on this problem.
Crossflow with twin 40 DCOE's, 1 choke intermittently over fuels on idle. When idling you can disconnect the plug lead from the plug with no
noticeable effect on running. The plug is sooted up which make me think the cylinder is receiving too much fuel on idle. The misfire continues up to
2500 ish rpm when the mains take over.
All of the idle jets are the same number and I have tried swapping them from choke to choke to move the problem around with no joy.
If you spray a little brake cleaner into the other 3 trumpets the revs will die then pick up. Spraying it into no. 4 trumpet makes no difference. I
have also noticed a major drop (60+ degrees) in temp on the header from the same cylinder when this is happening.
I can run the engine later in the day and it will be fine, then a few weeks later the problem will re-occur!
Anybody have any ideas?
Ta
Shaun
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atspeed racing
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| posted on 8/7/10 at 07:06 AM |
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If the carbs are not balanced correctly you will get the problem you are looking for. Also a twisted throttle spindle will send you in circles trying
to find the fault.
Get them set up correctly, it will make all the difference.
Alan
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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prawnabie
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| posted on 8/7/10 at 08:08 AM |
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Hi thanks for the reply
I have had them set up about 3 months ago. The problem happened before they were set up too and once whilst it was on the rolling road but cleared
itself.
It has happened twice since.
THanks
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atspeed racing
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| posted on 8/7/10 at 08:38 AM |
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Whilst it is confined to number four cylinder check for carb balance with a balancer.
Have you done a compression test?
Have you checked valve clearances?
Are you on points, are they correct? Use a dwell meter for an accurate reading.
This could still be due to no air flow through number 4 choke. This will give the impression of overfueling, but it is lack of air flow through the
butterfly.
I have had this many times even when other tuners have been through the carb setup.
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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prawnabie
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| posted on 8/7/10 at 11:51 AM |
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Hello
I am using a elec dizzy with a bestek module. compression is 180-190 across all the cylinders.
I have just bought a meter to check the balance.
Cheers
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JeffHs
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| posted on 8/7/10 at 11:52 AM |
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A daft suggestion based on my experience. Are you sure it's not your plugs? Before SVA I had my pinto running badly on DCOEs and despite a lot
of time and effort I decided to go back to the DGAV to clear SVA. On fitting the single carb, I found I'd got just the same issues. Changed the
brand new Bosch plugs for NGKs and it ran fine. After nearly 3 years I still haven't got the DCOEs on!
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