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Author
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Topic: Help with Autolite 4100.Please I'm desperate
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pony boy
Gearhead Posts: 443
From: n.y. n.y.
Registered: Jun 2000
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posted 11-04-2005 09:18 AM
 
Hello All,
As the title says I'm having a little technical difficulty with an autolite 4100.Basically This is on a stock "A" code 65 Mustang,The brief history is that the car had about 10k miles on a rebuild and I guess at that time it was converted to a 2bbl?The car ran great I decided to convert it back to a 4 bbl and found a correct 65 mustang numbered 4100 108.
I thought I was sort of knowledgeable on these carbs well the long story short,I rebuilt the carb.Installed it and have had some problems.The main Problem is The air/fuel screws can be bottomed out and the car still idles with little to no change when I attempt to adjust them.I figured I'm losing vacum so I have spraying all mounting and gasket surfaces,as well as carb base mainly around the throttle shafts with both wd 40 and carb cleaner in an attempt to see if the idle would change?Which it didn't.I then rechecked the carburtor base and spacer to see if they are flat/true they seemed fine,I even tried a different spacer because I figured why not.Upon reassembly I used new gaskets on the base,spacer,etc.Still same as before.I am hoping Alex and other knowledgeable carburetor people will chime in with their thoughts.I will give more info if needed I didn't want this post to be too long.Any help will be greatly appreciated.Thanks in advance.
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Scott H
Gearhead Posts: 1480
From: Chicago area
Registered: Mar 2005
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posted 11-04-2005 10:12 AM
Next thing I would check is if the secondary throttle plates are partially open, allowing air to sneak past them. It would be similar to a vacuum leak.Did you make sure the check ball was present for the seconday diaphragm? I had a carb that was missing one and got a replacement from Alex.
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Moneymaker
Administrator Posts: 29200
From: Lyons, IL, USA
Registered: May 99
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posted 11-04-2005 07:00 PM
Secondary throttle blades have an adjustment on 4100 Autolites.
The screw has a tendancy to freeze up.
Also, the wrong base gasket can cause a crossover vaccum leak on the primary side of some 4100 carbs.------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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pony boy
Gearhead Posts: 443
From: n.y. n.y.
Registered: Jun 2000
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posted 11-04-2005 07:47 PM
Thanks Alex and Scott.As far as the check ball in the secondaries,I had it in there and it moved free and clear,I also removed it and noticed no difference.I have had a problem with the secondaries hanging opened slightly but I figured I would get to that after I got the idle smoothed out.I made sure the secondaries were closed all the way and the problem still persists.As far as adjusting the secondaries I turned the screw out then turned it until it just touched,Then I went an extra 1/2 turn as per the Shop manual.Alex where exactly can the primaries leak vacuum? I assume it's in the carb meaning that The wd40 or carb cleaner sprayed at the base trick won't work.Thanks again guys for your answers I'm pretty stumped here and greatly appreciate any and all thoughts or suggestions.
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BornInAFord
Gearhead Posts: 610
From: Bend, OR, USA
Registered: Dec 2002
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posted 11-04-2005 07:54 PM
What manifold are you using? I had to use a 1/8" spacer on my Performer 289 because the original spacer was wider at the base than the thin manifold top and would leak where it overhung.
It sound though like the throttle plate is sticking open. Also check the choke arm at the top of the carb where the little nut screws in. This was overtightened on mine and wouldn't let the choke close all the way.
Daniel
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 11-04-2005 08:16 PM
Leaky "Dripping fuel" power valve ?
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Scott H
Gearhead Posts: 1480
From: Chicago area
Registered: Mar 2005
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posted 11-04-2005 09:22 PM
quote:
Originally posted by BornInAFord:
What manifold are you using? I had to use a 1/8" spacer on my Performer 289 because the original spacer was wider at the base than the thin manifold top and would leak where it overhung.
Very good point, the Edelbrock Performer 289 intake manifold has a very thin wall casting for the carb to sit on, and it will commonly mis-match the bottom of the 4100 carb, causing a vacuum leak.
Are you using a stock 4v intake or an aftermarket aluminum one?
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Moneymaker
Administrator Posts: 29200
From: Lyons, IL, USA
Registered: May 99
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posted 11-05-2005 12:19 AM
I assumed that you were using a stock intake.
If not, the leak would have been detected with the WD 40 test guys.
If you are using an open gasket you will get a crossover leak internally in front of the primaries where the throttle body (base) is scalloped (cut away) between the idle air bleed screws.
------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Scott H
Gearhead Posts: 1480
From: Chicago area
Registered: Mar 2005
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posted 11-05-2005 08:48 AM
I also assumed a stock intake since he is using a stock carb, and the spray test should have detected any external leaks.I was thinking about others who might encounter a problem when using the Edelbrock Performer 289 intake with the 4100. In the past I just used a metal shim type gasket sandwiched between two paper gaskets and had no problem. Alex, welcome back. Thoughts are with you, hope your trip was okay.
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Moneymaker
Administrator Posts: 29200
From: Lyons, IL, USA
Registered: May 99
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posted 11-05-2005 11:02 AM
Trip was long, but safe Scott.
I hope this was the end of it all.
Three in three months was enough. 
You have a package over at Rick's.
------------------
Alex Denysenko
Co-Administrator and Moderator NHRA/IHRA/SRA member and licensed Superstock driver
NHRA and IHRA SS/LA & SS/MA National Record Holder '00,'01,'02,'03,'04 &'05
First NHRA & IHRA 289 automatic Superstock Mustang in the TENS 06-99
First SS/MA in the TENS 04-03
IHRA division 5 Superstock Champion
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28 The Barry of BarrysGrrl Quote #1: "I never met a magazine mechanic I liked."
Quote #2: "Make sure brain is in gear before engaging mouth!"
Quote #3: "If you can't run with the big dogs, stay on the porch!"
www.moneymakerracing.com
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Scott H
Gearhead Posts: 1480
From: Chicago area
Registered: Mar 2005
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posted 11-05-2005 08:34 PM
Rick mentioned the package but I haven't been over to get it. All he said was it looks cool.
I'm trying to get my garage cleaned out this weekend to move my 66 convertible over here, that will give you the space you need to work on the '65 brake lines.
Glad you're home safe!
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 11-05-2005 09:28 PM
Leaky "Dripping fuel" power valve ?
Start with the basics. Go from there.If you
can run the idle screws in all the way, you
got a fuel leak inside your carb.If it has
a Holly style power valve,thats the first place to look at. Assuming the float level
is not a problem. Look at these two thing's
and see what you find?
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pony boy
Gearhead Posts: 443
From: n.y. n.y.
Registered: Jun 2000
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posted 11-06-2005 08:13 AM
Thanks for the replies so far,I'm running a stock intake on this car so that rules out the thin mounting flange idea.As far as a mounting gasket I was running a Fel pro 4 hole gasket but since I've had the carb off a couple of times I think I'm currently using one that came in the kit which has four scallops but they don't connect in the middle so it's not quite an open gasket,So I'm not sure because there was no change when I switched gaskets,bases,etc.
I am so stumped at this point,I would say I'm getting frustrated but I know when I eventually get this solved I'll be glad in a way that it happened that way I know exactly what to target next time.As far as a power valve etc.I put a kit in the carb and it probably only has about 50 miles on it.I set the float wet as per the shop manual,My question though would a bad float setting really cause this problem? I'm curious about what exact symptoms a faulty power valve would give?Thanks again for the info so far.Please let me know other thoughts that you have.
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 11-06-2005 10:55 PM
Look down thru the carb while it's idleing
and look real close at the boosters. Any
little drips coming off them? If not then
it's probably the power valve. I've had new
ones leak before too. If the boosters are
dripping, then you got a fuel level prob.
Like float level, leaky needle and seat.
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Jake11
Gearhead Posts: 246
From: Banning,Ca,USA
Registered: Oct 2005
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posted 11-06-2005 11:08 PM
FYI
Over90% of the carb O/H's I used to do on
Ford's back when they had carbs on them,
were due to leaky power valves. You should always keep a couple spares around. The Holly
ones you can get without buying the whole
kit.
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