Idle is low

[wwotr]

Hi guys! Have been busy with my move from Northern Ca down to SO CAL. My question is with my 72 Short Fleet. It was idiling fine. I had it shipped down here. Upon starting it up, it seems to be idiling about 150-200 RPMS too low. Its around 500 RPM in Park and drops down to about 400-450 in Drive.To the point where it starts to load up. Now the ONLY thing that has changed is the Elevation. I WAS at 3200' and now I'm at about 200'. Its an Edelbrock Carb that was just rebuilt about a year ago and has less than 500 Miles on that rebuild. Everyrthing else is fine. There is no missing, rough Idiling ect. Just wanted to get your thoughts before I upped the idle. Roger
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[turp mcspray]

Elevation will definitely be a factor. If your carb was in perfect tune before, it will be lean now. If you look in the Edelbrock carb manual, it will have an altitude formula. For every 1000 feet of change, you have to go richer or leaner, by a certain %. Most aftermarket carbs when new, are calibrated at sea level.

[swamp rat]

Temprature change and relative humidity can also affect the tune of the carb, if its warmer and dryer then its running a little richer than it was before, that can lower the idle a bit. I'd say its just time for a good tune up.

[wwotr]

Thanks guys!
Heres a kicker.
Yesterday the guy comes to install my Internet.
I back the Truck out (low idle) and all.
Then I go to move it back in.
I start it up and put it in gear., (it almost dies) so I give it some gas.
When I did, IU got this small backfire out the exhaust.
Then the Idle JUMPS UP to about 1200RPM. At this point, I'm power Braking it, so it doesnt run into the Garage.
I put it in Park, and hit the Gas fast (to kick it down).
It does, and now it runs/idles PERFECTLY, jusyt like it always has!!!

[Blue Rat]

Check your return spring on your throttle linkage.

[C. M. Wolf]

...And check your fuel filter and clean your carb out.

A dot of oil on the throttle control linkage joints couldn't hurt.

It sounds a bit sticky, make sure nothing is binding on the linkage or carb.

Michael

[swamp rat]

Then i would be checking the choke linkage not the throttle linkage, it soulds like it may be stuck or binding, 1200 is a normal high rpm when the choke is activated. Well actually i guess i'd be checking everything in the process but i suspect the choke linkage forst.

[C. M. Wolf]

Originally Posted by swamp rat

Then i would be checking the choke linkage not the throttle linkage, it soulds like it may be stuck or binding, 1200 is a normal high rpm when the choke is activated. Well actually i guess i'd be checking everything in the process but i suspect the choke linkage forst.

That's a real good point! Even electric chokes act up, vacume and manual choke systems do too and need to be replaced.



Michael

[wwotr]

Originally Posted by C. M. Wolf

...And check your fuel filter and clean your carb out.

A dot of oil on the throttle control linkage joints couldn't hurt.

It sounds a bit sticky, make sure nothing is binding on the linkage or carb.

Michael

I have some WD-40 Handy, can I use this in a bind?

[swamp rat]

it won't hurt!

[wwotr]

So heres a picture I took under my Hood of my Elebrock Carb.
Can anyone tell me if what I'm pointing at (and is Circled in White),
is the Idle Speed screw?

[Allensracing]

I used to drive a car transport truck. if you had it shipped on a truck, I probably know what happened.
when your vehicle is tied down on a semi trailer, it manages to jar loose every bit of everything in the fuel system. you might have had some crud in the fuel bowl, or in the gas tank, or fuel line that broke loose during transit.
I can not begin to count the number of classic vehicles that I loaded running perfectly, and unloaded running rough and back firing. yes altitude can cause problems, but it happened to me when it was picked up and dropped off at close to sea level.
change the fuel filter just in case.

[wwotr]

Originally Posted by Allensracing

I used to drive a car transport truck. if you had it shipped on a truck, I probably know what happened.
when your vehicle is tied down on a semi trailer, it manages to jar loose every bit of everything in the fuel system. you might have had some crud in the fuel bowl, or in the gas tank, or fuel line that broke loose during transit.
I can not begin to count the number of classic vehicles that I loaded running perfectly, and unloaded running rough and back firing. yes altitude can cause problems, but it happened to me when it was picked up and dropped off at close to sea level.
change the fuel filter just in case.

That is a very good point and thanks for chimimg in.
My Truck was on a single enclosed trailer,
by itself being towed by a Flatbed tow Truck.
I'm sure there was some amount of Jarring, but not sure in comparison to a BIG Transport Hauler.

[Allensracing]

my hauler rode on airbags, and had very little jaring. it was more like being on a boat, a mutlidirection rocking. somehow it moved stuff around that normal driving did not do, yet i could leave half a soda on the floor and it wouldnt fall over after a thousand miles of driving.
I dont understand it, I just know it happened.

[swamp rat]

Originally Posted by wwotr

So heres a picture I took under my Hood of my Elebrock Carb.
Can anyone tell me if what I'm pointing at (and is Circled in White),
is the Idle Speed screw?

Yes thats the idle screw.

The 2 screws on the front of the body close to the base of the carb are the air/fuel mix screws.

[wwotr]

Originally Posted by swamp rat

Yes thats the idle screw.

The 2 screws on the front of the body close to the base of the carb are the air/fuel mix screws.

SWAMP RAT....

THANK YOU!!!!!!!!!!