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4100 way too rich

April 15 2017 at 7:12 AM
Jason  (Login 60sIron)
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My Autolite 4100 is running waaay too rich. Is it possible to have an internal leak where it just dumps raw gas into the intake? What should I be looking for?

 
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Bob
(Login machoneman)
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First...

April 15 2017, 7:16 AM 

I'd warm it up and stick your head into the carb and see if fuel is dribbling from the boosters. If so, check the floats and needle/seat assembly. Btw, did it just start running rich? Was the engine laid up over winter? More details would help.

 
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Jason
(Login 60sIron)
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Some history

April 15 2017, 7:46 AM 

It ran rich when I bought it. It had some broken parts and the secondaries were wired shut, so I sent it away to get rebuilt. It came back looking right and with functioning secondaries, but it still runs really rich.

 
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Jason
(Login 60sIron)
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Also

April 15 2017, 7:58 AM 

The carb is sitting on the shelf, I replaced it with an Edelbrock to confirm that the Autolite was the source of all the problems related to the richness problems:

* No start when warm/hot
* Surging at cruise
* Massive amounts of soot (more like tar shooting out the tail pipes)
* Unsteady idle

Now I would like to get this Autolite back on my car, but I'm not very familiar with these.

Where are the adjustments?
What typically goes wrong?

 
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Bones
(Login boneyard51)
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Re: 4100 way too rich

April 15 2017, 7:55 AM 

Check your power valve

 
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Bobby Spears
(Login x4rdtech)
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Re: 4100 way too rich

April 15 2017, 8:00 AM 

Yep biggest known problem with those.

 
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fordsel
(Login fordsel)
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i agree

April 15 2017, 8:04 AM 

things just wear out, been there done that. sometimes you just have to stand on the valve covers and practice your golf swing.

 
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Bones
(Login boneyard51)
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Power valve

April 15 2017, 8:07 AM 

Carefully remove your carb, keeping it level. Remove the four screws covering your power valve. If there is gasoline present, your power valve is junk. Bones

 
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Jason
(Login 60sIron)
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Good info, unfortunately...

April 15 2017, 8:47 AM 

Way too late. This has been sitting on a shelf for years, and I'm sure it has been flipped over at some point. Is there another way to test the power valve?

 
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Dan
(Login lowrider)
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Re: Good info, unfortunately...

April 15 2017, 8:54 AM 

Make sure the rebuilder didnt screw in a Holley power valve. They will blow out quickly. The Holley has a small lip on the outer sealing edge while the Ford is flat. I would just pick one up, they're not that $$$.

 
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Bob
(Login machoneman)
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Here's the deal:

April 15 2017, 8:59 AM 

Most even cheap PV testers are $40 or so. A new PV is under $10.....meaning only a shop mechanic would buy one for the cost difference.

Plunk the carb back on the engine, fire it up and shut her off. Then as mentioned pull the cover off and check for fuel in the PV well as noted above.



    
This message has been edited by machoneman on Apr 15, 2017 10:25 AM


 
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Jason
(Login 60sIron)
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Maybe I'm missing something

April 15 2017, 9:06 AM 

The power valve cover is on the bottom of the carb, I don't think you can get to it without taking the carb off the intake.

 
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Bob
(Login machoneman)
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The....

April 15 2017, 10:30 AM 

vid here may be of more help than explaining:

https://www.youtube.com/watch?v=1-K842VB_J0

What I should have said was have a pal lift the carb up while you remove the PV cover screws. Sorry!

 
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Dan
(Login lowrider)
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Re: The....

April 16 2017, 5:50 AM 

As mentioned earlier, I would put it back on and run it a bit. You can ck to see if the boosters are dripping and turn the adjustment screws to see how they respond. After you've run it just pull the carb off to ck the power valve. The power valve doesn't know if it's upside down or right side up. The fuel won't drain back from the cover or evaporate if you flip the carb over. If there's any wetness under the cover the power valve is blown.

 
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Bob C
(Login redstangbob)
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there are 2 PV gaskets

April 15 2017, 9:05 AM 

that come in most kits, the rebuilder may have used the wrong one. A typical PV test is to turn mixture screws in at idle, if it keeps running the PV is usually bad.

 
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winr1
(Login winr1)
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Jason ... what intake and were you using a spacer plate ?? ..

April 15 2017, 2:06 PM 

You can check a PV with your mouth using vacuum



Ricky.


    
This message has been edited by winr1 on Apr 15, 2017 2:07 PM


 
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Jim
(Login FormerlyCyclonic66)
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My first choice: FLOAT CLIP

April 16 2017, 6:34 AM 

There is a wire clip that secures the pivot end of the float. It clicks into a groove in the casting for the needle/seat. Without this clicked into place, the whole float will raise with fuel, including the end that should pivot down to hold the needle down.


At 10:16 into this video, it's very briefly shown.
https://m.youtube.com/watch?v=JyYEc6yOm1w

 
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