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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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 Posted: Thu Apr 10, 2003 9:47 pm Post subject: carb question |
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Hi !
I have a question. When you tighten the mixture screw on the IDF carbs do you allow more mixture to the engine or less?
Thanks! |
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TimoJ
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| Posted: Wed Apr 16, 2003 7:16 am Post subject: Mixture |
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Hi
Closing screw --> weaker mixture. Correct mixture is usually between 2 and 3 turns open. Be careful when screwing in to avoid damage -- no force when the screw stops.
Hope this helps
TimoJ
btw, are carbs getting rare here, cause no answers? |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Wed Apr 16, 2003 10:56 am Post subject: re |
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Hi!
Thanks for the reply. It helped.
My mixture screw is about 4 turns out. If I screw it from that position the engine starts to run worse.
I've read about the carbs on the 33's and I saw that 36 IDF is a standard carb for the 1.3 liter engine. Mine has a 40 IDF with 28 mm venturis. I guess more air needs more fuel. |
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alexj
Alfasud
Joined: 25 Mar 2003
Posts: 66
Location: New Zealand
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| Posted: Thu Apr 17, 2003 7:50 am Post subject: |
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| Latter cars went to 40 IDF but main venturi remains the same, so quantity of air is probably about the same as before. By the way, more of us have carbs but some of us just forgot which way around it was! Thankfully Timo remembered. |
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TimoJ
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| Posted: Wed Apr 23, 2003 5:25 am Post subject: Butterflies |
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Hi
Do You have the carbs othervice set u properly? The butterflies should be closed or veery near closed. If You have to adjust mixture 4 turns open, it seems to me that the mechanics of the throttlelinkage are not in correct position, ie. crossed somehow.
Check to see if effects. If they are balanced, the engine does not shake at all.
Any opinions?
TimoJ 1,5ti |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Wed Apr 23, 2003 10:16 am Post subject: re |
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| Quote: |
Hi
Do You have the carbs othervice set u properly? The butterflies should be closed or veery near closed. If You have to adjust mixture 4 turns open, it seems to me that the mechanics of the throttlelinkage are not in correct position, ie. crossed somehow.
Check to see if effects. If they are balanced, the engine does not shake at all.
Any opinions?
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I've overhauled the carbs before tuning them. I've checked the butterfly's and they close prefectly. My idle screw is about 1/4 turn in. I also have a vacuum meter and the flow on all carbs is equal with all air bypass screws closed. The engine shakes a bit when it is cold (water temp about 40 °C).
How do I check the throttlelinkage position? |
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TimoJ
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| Posted: Thu Apr 24, 2003 6:46 am Post subject: Linkage |
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Hi
As you have measured the airflow and checked the butterflies, the carbs are in balance. Those linkages effect only when pushing pedal slightly. Look behind carbs, there is adjusting screws in linkage. There should be 1mm gap under the screw-- to avoid linkage pressing the throttle open.
I suppose You know this because of all tinkering done 
Maybe exhaust test could tell the mixture for sure?
Suggestions?
TimoJ |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Thu Apr 24, 2003 1:31 pm Post subject: re |
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| Quote: |
Hi
As you have measured the airflow and checked the butterflies, the carbs are in balance. Those linkages effect only when pushing pedal slightly. Look behind carbs, there is adjusting screws in linkage. There should be 1mm gap under the screw-- to avoid linkage pressing the throttle open.
I suppose You know this because of all tinkering done
Maybe exhaust test could tell the mixture for sure?
Suggestions?
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Hi!
I've checked the gap when I was putting the carbs back on the engine.
The exhaust test tell's me the the mixture is little rich (about 5 % CO and it should be 3.5% CO) but if I lean the mixture, the engine runs worse.
Generally the engine is in very good condition. I't has only about 100.000 km (60.000 miles). I've put new plugs (Lodge 25HL), new rotor arm and distributor cap. The ignition is set about 9° advance. |
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TimoJ
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| Posted: Thu May 08, 2003 6:45 am Post subject: carbies |
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Hi Neo
Did You find solution?
TimoJ |
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neo
Alfasud
Joined: 14 Mar 2003
Posts: 68
Location: Rijeka, Croatia
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| Posted: Thu May 08, 2003 10:25 am Post subject: re |
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| Quote: |
| Closing screw --> weaker mixture. |
Hi!
That is not correct for my carbs. I have 40 IDF. I've fixed the car and now has about 2.5 % CO (limit is 3.5%) and consumes about 9.5 liter for 100 km urban cycle.
When the mixture screw is totally tighten the mixture is closed. When you slightly open the screw then you have full rich mixture. The more you unscrew the leaner the mixture is becasue less fuel comes to the engine.
My screw is turned out about 5 turns. The car doesnt shake anymore, it accelerates without any gaps, and the fuel economy is much better.
It doesnt pop on the exhaust anymore when going downhill.
Neo |
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