81 rough idle...
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Joined: May 2002
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From: boxford MA
81 rough idle...
i just bought the 81, and only thing that is noticeable is a really shaky idle...
when the clutch is in and sitting at a light, the whole car is shaking.. i am not sure if this is normal, but my dad says it could be running lean. could someone explain exactly what rich and lean mean? and is this a common occurance on older models, or should i have something looked at. its a new edlebrock carb (incase that matters)
thanks
when the clutch is in and sitting at a light, the whole car is shaking.. i am not sure if this is normal, but my dad says it could be running lean. could someone explain exactly what rich and lean mean? and is this a common occurance on older models, or should i have something looked at. its a new edlebrock carb (incase that matters)
thanks
Race Director
Joined: Nov 2000
Posts: 11,872
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From: Waterloo ontario Canada
Re: 81 rough idle... (deftones1407)
I wonder if you are running on all 8 cylinders. If you have one missing it will cause this shake. As for running lean at idle mostly the older carbed engines have a problem with running too rich, like the choke is on but it isn't.
If you have headers it is easy to check for a missing cylinder. When first starting the motor I have a squeeze bottle and shoot a little water on each header pipe and watch if it boils instantly. A missed cylinder will stay cold for a long time. If you are quick with the hands you can quickly find a cold pipe.
With cast iron manifolds I have put a dab of grease on each outlet and watched when the motor is started for a cylinder that is not firing.
Either way shaking is not normal and either a cylinder is missing or the carb is really out of adjustment.
If you have headers it is easy to check for a missing cylinder. When first starting the motor I have a squeeze bottle and shoot a little water on each header pipe and watch if it boils instantly. A missed cylinder will stay cold for a long time. If you are quick with the hands you can quickly find a cold pipe.
With cast iron manifolds I have put a dab of grease on each outlet and watched when the motor is started for a cylinder that is not firing.
Either way shaking is not normal and either a cylinder is missing or the carb is really out of adjustment.
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Joined: May 2002
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From: boxford MA
Re: 81 rough idle... (norvalwilhelm)
that sounds scary.... it is in PRISTENE shape... so i am hoping that it isn't one of the cylinders not running... once you rev it up past like 1100 rpms.. its smother than any other car i have driven. how hard is it to adjust the carb? (thats what my dad was suggesting)
Pro
Joined: May 2002
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From: Petaluma CA
Re: 81 rough idle... (deftones1407)
Lots of possibilites....but carb and miss are the usual suspects. Thanks for the tip of water on headers or grease on manifolds to spot cold cylinder.
You might look at running engine in the dark to see if a plug wire is arcing. Or plug wire could be loose. Could be bad or fouled plug. Check timing. See what a vacuum guage shows. Bad carma. Very dirty air filter.
Gotta be fuel, spark or compression. Please let us know.
You might look at running engine in the dark to see if a plug wire is arcing. Or plug wire could be loose. Could be bad or fouled plug. Check timing. See what a vacuum guage shows. Bad carma. Very dirty air filter.
Gotta be fuel, spark or compression. Please let us know.
Drifting
Joined: Jan 2002
Posts: 1,645
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From: Schaumburg IL
Re: 81 rough idle... (deftones1407)
i just bought the 81, and only thing that is noticeable is a really shaky idle...
when the clutch is in and sitting at a light, the whole car is shaking.. i am not sure if this is normal, but my dad says it could be running lean. could someone explain exactly what rich and lean mean? and is this a common occurance on older models, or should i have something looked at. its a new edlebrock carb (incase that matters)
thanks
when the clutch is in and sitting at a light, the whole car is shaking.. i am not sure if this is normal, but my dad says it could be running lean. could someone explain exactly what rich and lean mean? and is this a common occurance on older models, or should i have something looked at. its a new edlebrock carb (incase that matters)
thanks
Rich - too much fuel is being put into the engine for the engines ability to burn it.
Lean - the opposite just too little.
Both are a function of the carbs idle circuits and the jetting of the carb.
You say when the clutch is in and sitting at a light the car is shaking. Does the car do this in neutral with the clutch out?
Let us know.
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From: boxford MA
Re: 81 rough idle... (bigvette1)
it does this when the clutch is in... and when the clutch is out in nuetral... my dad says the carb needs to be tuned.. its an aftermarked edlebrock performer carb... so thats what i was thinking... any opinions?
