Rebuilding an Autolite 4100 carb

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
I have never rebuilt a carb before, and I don't know the correct names for the parts of the carb. Please help me by correcting my terminology and identifying the parts, thanks!

That said, here are my pics and comments so far. The carb ...

P1000649-800.jpg

P1000650-800.jpg

P1000651-800.jpg

P1000652-800.jpg

P1000653-800.jpg

P1000654-800.jpg

P1000655-800.jpg

P1000656-800.jpg

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there are 8 of these bolts holding the top down ...

P1000659-800.jpg


Bolts out, next problem, the lever thing ...

P1000660-800.jpg


i took this c ring out ... then it fell on the ground and i can't find it! :(

P1000662-800.jpg


The underside of the cover ...

P1000666-800.jpg


There's a little plastic thing that the rod goes through ...

P1000665-800.jpg


With the cover off ...

P1000667-800.jpg

P1000668-800.jpg


The gasket ...

P1000669-800.jpg


With the gasket off ...

P1000670-800.jpg

P1000671-800.jpg


The venturi bolts ... note that they look different ...

P1000672-800.jpg


They are labeled on the bottom ... "D K" is on the horn side ... it is cleaner ...

P1000676-800.jpg


"A B" in on the other side ...

P1000675-800.jpg


This bolt goes on the D K side ...

P1000679-800.jpg


The undersides of the venturis ...

P1000680-800.jpg


With the venturis out ...

P1000682-800.jpg


I took this out next ...

P1000683-800.jpg


With the venturi gaskets off ....

P1000684-800.jpg

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The A B one has this little gasket, the D K one does not ...

P1000687-800.jpg


A view of the tubes under the D K venturi ...

P1000689-800.jpg
 
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2+2GT

10 Year Member
Apr 25, 2009
3,333
10
69
Southeastern Pennsylvania
Your secondaries will never open. The vacuum diaphram tube is badly bent, and must be straightened. The carb is not a Mustang carb, Mustangs never had the secondary kickdown lever, but if it's a 289 carb, that won't matter. It seems pretty unmolested, you still have the steel secondary diaphram lever. Very rare. What is the P/N stamp on the mounting flange? What size are the venturis- 1.08, or 1.12? The hole where the high-idle vent was removed must be plugged, or you'll have a permanent vacuum leak. That fuel inlet is wrong, it cam from a hardware store. What year is your car?
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
you clearly know alot about this stuff. can you recommend a good resource for rebuilding my carb?

i've never done this before and it is probably obvious that i don't know what i am doing (i even called the boosters venturis!)

the carb is the one that was in my 1967 fairlane with a 390 FE engine. i figured that since the mustangs of the era also had carbs (didn't some of them also have 4100s?), it would not be out of line to record the project here. after all, this is about rebuilding the carb, and not about the fairlane at all. if that logic doesn't fit with the rules or spirit of this forum, then let me know and i will abort this thread.

thanks
 

bnickel

Founding Member
Aug 21, 2002
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rebuilding a 4100 is a piece of cake as long as you pay attention to the little details. I will say that you should probably get a rebuild kit from the Ford dealer, they still stock them or can get you one pretty quick. that said I used a bunch of different kits to get all the pieces I wanted when i built my 58/59 ONLY mercury 1.19 venturi 4100. i bought up several NOS 50's and 60's Holley and Tomco carb kits and also bought a GP Sorensen kit from autozone to get some of the small pieces and fresh gaskets. I also used the larger needle and seats from a Carter AFB (Edelbrock is the same) and a Holley power valve, actually i have a few different holley PV's so I can match it to my engine once I have it built up. I also bought a holley secondary diaphragm spring kit so again I match what I need to the engine once it's done as well as I added an electric choke to it as well, though I do stil plan on utilizing the hot air tube from the exhaust manifolds as well. At some point I also plan on buying a used Summit street/strip carb, the new one that's based on the old holley 4010, and robbing the booster clusters out of it and buying the idle and high speed air bleed kits from Summit at some point to further tune the carb to my engine. once I'm done it should be one hell of a sleeper of a performance carb and look totally stock.......::evil: :burnout:
 

2+2GT

10 Year Member
Apr 25, 2009
3,333
10
69
Southeastern Pennsylvania
you clearly know alot about this stuff. can you recommend a good resource for rebuilding my carb?

i've never done this before and it is probably obvious that i don't know what i am doing (i even called the boosters venturis!)

the carb is the one that was in my 1967 fairlane with a 390 FE engine. i figured that since the mustangs of the era also had carbs (didn't some of them also have 4100s?), it would not be out of line to record the project here. after all, this is about rebuilding the carb, and not about the fairlane at all. if that logic doesn't fit with the rules or spirit of this forum, then let me know and i will abort this thread.

thanks
If you are using it on a 390 Mustang, you'll be fine. Your photo documentation is first-rate, you'll have no trouble finishing the job. You'll need a rebuild kit, these are common. They typically do not come with the secondary diaphram, make sure you get the one for the steel lever. I believe the Glazier/Nolan G08214 is that one. Most suppliers expect you to switch to the nylon lever. Your fuel inlet should be a small filter.
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
Some questions:

(1) The bowl on the choke side had fuel in it, but the one on the other side was empty. Does that mean anything? The last time I drove the car was about a week before the pictures were taken. I would think that if it had filled up then, then it should still have had some fuel in it.

(2) "The vacuum diaphram tube is badly bent". Where is that tube?

(3) "The hole where the high-idle vent was removed must be plugged". Where is this vent and the hole?

Sorry about being such a novice with this stuff.
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
The hole where the high-idle vent was removed must be plugged, or you'll have a permanent vacuum leak.
Thanks. Re the high-idle hole, it was and is plugged, it is just not visible because of the camera angle.

Re the diaphram tube, I see what you mean. Mine is bent such that the opening at the end is centered above the left primary booster, and in your picture, it looks like it should be a right angle and centered between the boosters. I'll look into bending it back or replacing it.

Thanks again for the help, I appreciate it. Any thoughts on the secondary reservior being empty?

I noticed that one of the idle air bleed holes above the secondary booster base is clogged. That made me start to wonder if there might be a syphoning effect, which might explain the empty bowl and the rich condition. Does that make any sense?
 

2+2GT

10 Year Member
Apr 25, 2009
3,333
10
69
Southeastern Pennsylvania
Re the diaphram tube, I see what you mean. Mine is bent such that the opening at the end is centered above the left primary booster, and in your picture, it looks like it should be a right angle and centered between the boosters. I'll look into bending it back or replacing it.

Thanks again for the help, I appreciate it. Any thoughts on the secondary reservior being empty?

I noticed that one of the idle air bleed holes above the secondary booster base is clogged. That made me start to wonder if there might be a syphoning effect, which might explain the empty bowl and the rich condition. Does that make any sense?
a) No, it should be down inside the left venturi, but not in the center of it.

b) Maybe. Could be many reasons for it, just carefully clean and assemble it and you should be fine.
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
Thanks. I found a thick manual that covers my car and it has a very informative section on the 4100 carb, so hopefully my questions and comments will start to be more informed.

That said, if I am unable to bend the diaphram vacuum tube back without ruining it, is it possible to replace the tube, or will I need to replace the cover with one whose tube is good?

Lastly, if the tube is bad, then wouldn't that mean that a vacuum would not be present, in which case the secondaries would open prematurely, as opposed to not opening at all? Don't they work in such a way that the vacuum keeps them from opening?

OK, I admit it, my questions may not be that much more informed ... :(
 

2+2GT

10 Year Member
Apr 25, 2009
3,333
10
69
Southeastern Pennsylvania
That said, if I am unable to bend the diaphram vacuum tube back without ruining it, is it possible to replace the tube, or will I need to replace the cover with one whose tube is good?

Lastly, if the tube is bad, then wouldn't that mean that a vacuum would not be present, in which case the secondaries would open prematurely, as opposed to not opening at all? Don't they work in such a way that the vacuum keeps them from opening?
The tube is brass, and should bend, especially if it is annealed. Besides, you have no choice. Make sure you know exactly where to go when straightening it.

The secondaries are normally closed, and vacuum at the tip of that tube, when the primaries are sucking lots of air, opens the secondaries.
 

BlackVert

15 Year Member
Oct 3, 2003
5,589
8
88
Bethesda, MD
The check ball that fell out of the power valve line when i turned the carb over.

P1000694-800.jpg


PN C5AF F

P1000696-800.jpg


From below ...

P1000697-800.jpg


Back side underneath ...

P1000699-800.jpg


Front side underneath ...

P1000701-800.jpg


Secondary vacuum tube ...

P1000703-800.jpg


From where this is located, and 2+2's description of where it should be, I'm starting to think that it was designed to be like this on this carb ...

P1000707-800.jpg


Another angle of it ...

P1000708-800.jpg
 

horseballz

10 Year Member
Sep 30, 2009
820
19
39
Las Vegas, NV
Chris,
You should note that the main difference between your "D-K" booster and the "A-B" booster is that the "D-K" and it's associated screw have a passage way for the accelerator pump shot/squirt. Don't mix them up, as they both fit each others' locations. As far as the little washer/gasket between the screw and booster, I think both the front and rear should have one, but I am not 100% certain. As for power valve selection, start with stock and then when engine is running and well tuned, note the inches of vacuum at idle and divide it in half for the number of your power valve. If you do a good job, you should be quite happy, as these 4100 are AWESOME carbs when set up right.
Good Luck,
Gene
 

Realmongo

I prefer to be called "Evil Genius"
Founding Member
Oct 10, 2001
2,310
40
99
Western Mass
The C5AF-F carburetor is about 600 CFM and was used on full size 1965 Fords with the 352 engine with automatic transmission.
 
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