Autolite 2 v carbureter idle problems

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poolplayer1

Senior Member
The autolite 2100 carbureter on my 302 engine seems to have a problem. I did put a kit on it last year. The problem is this: With the air cleaner off,I can adjust the 2 idle screws and have a nice idle speed. When all done,I put the air cleaner on and at this time,the idle speed raises up by itself.
I made sure that the base of the cleaner is not pushing on the throttle when I sit it over the carb.Could this be an internal part of the carb. causing this problem or maybe a vacuum leak somewhere.Im pretty sure that we have some really good carb guys here in this site that may be able to help out.
Thanks for all your help.
 
Just guessing....
Is it an original air cleaner housing or something else? Is the filter element larger or smaller than original, or need cleaning/replacement?
The idle speed could be changing because the air cleaner is affecting the fuel/air ratio. Running better with a (slight?) restriction of incoming air could indicate a vacuum leak.

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Thanks guys for your response. Its a 1955 ranchwagon.The original motor was a V8 272 with a 3 speed manual transmission.We took the 272 out and put in this 1968 302.We also removed the old ****** and put in a automatic C4 transmission. All this was done back in the 80's. This autolite came with the 302 so its original to the motor. The air cleaner housing is an after market chrome type that I put in at the time I put the 302 in the wagon.Today,I noticed that if I put my hands over the carbureter opening (I'm sure there is a name for it ) the idle speed increases. I have all new gaskets in the carb. including the base gasket.It also has a spacer between the intake and the base of the carb. This spacer has a hose that goes over to the valve cover and connects to the pcv valve. Hopefully this info will help you and maybe can come up with some suggestions for me to look at.Thank you very much.
 
If that never happened when you first put on the aftermarket air cleaner years ago, then it sounds like you missed something when you went through the carburetor. Did you just replace the gaskets, or did you completely disassemble and look at things ? Did you set the float to the correct level ? Did you adjust the two idle mixture screws when the engine was warm and idling at the speed you desired to get the smoothest idle (highest vacuum/RPM) ?


Sal
 
poolplayer1 said:
The problem is this: With the air cleaner off, I can adjust the 2 idle screws and have a nice idle speed. When all done,I put the air cleaner on and at this time,the idle speed raises up by itself.
Click to expand...

poolplayer1 said:
We took the 272 out and put in this 1968 302.

This autolite came with the 302 so its original to the motor.

The air cleaner housing is an after market chrome type that I put in at the time I put the 302 in the wagon. Today,I noticed that if I put my hands over the carbureter opening (I'm sure there is a name for it ) the idle speed increases
Click to expand...

One way to check for a lean run condition is to put a shop rag over the carb throat while running. If speeds increases (instead of choking out), it indicates the engine is running lean.

Also, when balancing A/F ratio, it is best to do so with the ACL mounted if the mixture screws are accessible. When you balance one w/o the ACL and then mount the ACL, the ACL is restricting air flow and the mixture settings.

You say a 1968 302. Does it still have the dual vacuum advance canister? That is part of IMCO and if any part of the system is defective (or someone tried to defeat it incorrectly), it may operate off manifold vacuum continuously instead of a back and forth of ported/manifold vacuum making curb idle difficult to arrive at..

You say an aftermarket ACL. If you just mount the ACL base is there any idle speed change? If so, it may be interfering with the throttle linkage and/or choke linkage. Is it a quality aftermarket or a J.C WHITNEY SPECIAL? What is the element made of?

PCV SYSTEM serviced and operating properly? This will throw mixture off also.
 
Thanks again for your great input on this matter. I checked again to see if the air cleaner base might be interfering with the throttle linkage and its not. The PVC is a new valve. The vacuum canister is a single port type. I am going to try all the things you mention here in your post and try adjusting both idle screws to see if I can get it running good. Will post again later.
 
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