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righ RPM idle...sierra 1990
Posted: Tue Apr 19, 2011 4:39 pm
by suzuki lj80
Hey guys
Bought my first car a few weeks ago, reconditioned the head, and it idles really high (around 1500 - 2000)
i saw that there's an adjuster on the throttle cable, but is there any other way that I can bring the idle down
I also made sure that the 4 bolts that hold the carby down were tight because I took the carby off because I was having some fuel problems (all sorted now)
Anyone 2 cents would be appreciated!
Timmy
Re: righ RPM idle...sierra 1990
Posted: Tue Apr 19, 2011 9:54 pm
by V.W.Dave
There is a idle adjustment screw on the head side of the carby its a little hidden. If you can't fix it there I would be looking at timing of the dizzy as well as air leaks.
Re: righ RPM idle...sierra 1990
Posted: Wed Apr 20, 2011 4:37 pm
by thehanko
V.W.Dave wrote:There is a idle adjustment screw on the head side of the carby its a little hidden. If you can't fix it there I would be looking at timing of the dizzy as well as air leaks.
x2
not the throttle cable adjustment is not something you use to adjust idle - its purely for adjusting the freeplay in the cable and it should be a little bit loose. idle is adjusted with the idle screw.
as dave said check for air leaks, an easy way of doing this is spraying carbi cleaner ontothe outside and see if the engine misses or dies, this would indicate an air leak.
Re: righ RPM idle...sierra 1990
Posted: Wed Apr 20, 2011 5:08 pm
by suzuki lj80
thanks guys, I found out today, after taking it for a few laps around the shop im working on it at, the idle dies down after about 2-3 mins of idle....is this normal??
Re: righ RPM idle...sierra 1990
Posted: Wed Apr 20, 2011 5:49 pm
by V.W.Dave
suzuki lj80 wrote:thanks guys, I found out today, after taking it for a few laps around the shop im working on it at, the idle dies down after about 2-3 mins of idle....is this normal??
Not really. But every engine is a little different. Have you used a timing light to check if you spark is in time before you mess with the idle to much? Rebuilt head would have been decked/machined meaning it is a little shorter then when it was last on the block. If you just set the distributor back to the exact same place it will be wrong. Once you have the spark timed correctly then mess with the idle screw.
Something else to think about is when you had the carby off it was more then likely flipped over and turned around and blahh blahh blahh meaning any junk that was sitting at the bottom of the fuel bowl was disturbed and is now more then likely stuck in the jets. A easy way to clear them out is with the engine running at idle slowoly with your hand cover the intake till about 2/3s of it is covered this will create a higher then normal suction through the ventura sucking harder on the jets and will clear them out (most of the time). With your hand still there bring the revs up till it starts to die. Back it off a little and let it sit there for about 10 second.
Hope that made some sence.
Re: righ RPM idle...sierra 1990
Posted: Thu Apr 21, 2011 5:01 pm
by suzuki lj80
everything with the engine is now going good, thanks for your help guys, bought my first modification today (apart from the seats)....went out and bought myself a 1kg fire extinguisher from super crap auto, hopefully I wont have to use it
Re: righ RPM idle...sierra 1990
Posted: Wed Apr 27, 2011 1:20 pm
by thehanko
suzuki lj80 wrote:everything with the engine is now going good, thanks for your help guys, bought my first modification today (apart from the seats)....went out and bought myself a 1kg fire extinguisher from super crap auto, hopefully I wont have to use it
a mate of mine bought a sierra and i gave him a fire extinguisher as a car warming present
![armsup :armsup:](./images/smilies/icon_ruff.gif)
Re: righ RPM idle...sierra 1990
Posted: Thu Apr 28, 2011 1:41 pm
by zookimal
I see the problem has been solved already but this might help for future searches.
The fast idle/idle up gear on the front of the carby can jam up or end up out of adjustment causing idle speed issues. I've had 2 older carbs do this and it'll sit the idle between 1500-2000rpm.