My 1989 1000cc mini doesnt seem to want to idle anywhere below 2000rpm. It has had a recon su carb fitted which had the hole in the throttle butterfly blocked up. The ignition timing is set correct, the butterfly is closing ok but it still doesnt want to idle below 2000, ive loosened the idle screw right out so the butterfly is completely closed and it does lower the revs very slightly but i cant get it to go any lower, as far as i know there are no air leaks anywhere. Would it pay to re-drill the hole in the butterfly and would this solve the problem?
Car Doesnt Idle Low
Started by
tobz350i
, Dec 10 2010 07:31 PM
5 replies to this topic
#2
CHUNKY365
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Posted 11 December 2010 - 12:30 AM
A couple of things to check.
Try the mixture, it might be too rich.
The choke has a 'fast idle' screw, which raises the idle when you pull the choke on. This may need adjusting.
Also look at the cables, is there enough slack when both the choke and throttle are 'off'. May need to adjust either or both cables.
These are the more obvious things to look for.
The slightly harder things to spot are things like the setting of the needle carrier inside the carbs bell chamber.
Take off the bell chamber and look to see if the collar holding the needle is seated correctly (Haynes will give you a guide, or the Burlen website)
Check for air leaks. The easiest way is to spray WD40 around the inlet manifold and carb. If the engine revs drop then you have an airleak, if they don't then more than likely one of the above.
Try the mixture, it might be too rich.
The choke has a 'fast idle' screw, which raises the idle when you pull the choke on. This may need adjusting.
Also look at the cables, is there enough slack when both the choke and throttle are 'off'. May need to adjust either or both cables.
These are the more obvious things to look for.
The slightly harder things to spot are things like the setting of the needle carrier inside the carbs bell chamber.
Take off the bell chamber and look to see if the collar holding the needle is seated correctly (Haynes will give you a guide, or the Burlen website)
Check for air leaks. The easiest way is to spray WD40 around the inlet manifold and carb. If the engine revs drop then you have an airleak, if they don't then more than likely one of the above.
#3
icklemini
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Posted 11 December 2010 - 07:58 AM
Assuming theres nothing mechanical holding the throttle open. then there is an air leak somewhere..
How are the engine breathers connected up?
Drilling a hole in the throttle disk will only let more air in at idle..
How are the engine breathers connected up?
Drilling a hole in the throttle disk will only let more air in at idle..
Edited by icklemini, 11 December 2010 - 07:59 AM.
#4
tobz350i
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Posted 11 December 2010 - 10:56 AM
will recheck for any air leaks today. all breathers are connected and are jubilee clipped up, all new breather pipes too so shouldnt be a split pipe. It has idled like this since its first run as its a newly built engine.
#5
icklemini
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Posted 12 December 2010 - 09:01 AM
if the butterfly is closed (check that the idle screw and the operating arms arent jamming) then it wont start / idle.
dis connect the cables, close the throttle, and go from there.
Air leak at the manifold?
Vac Advance?
dis connect the cables, close the throttle, and go from there.
Air leak at the manifold?
Vac Advance?
#6
ste88
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Posted 12 December 2010 - 09:05 AM
mine used to idle high, and it turned out to be an air leak where the spindle goes into the body
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