Rebuilding an Autolite 4100 carb

BlackVert · Feb 12, 2011

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 ...

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

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

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

The underside of the cover ...

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

With the cover off ...

The gasket ...

With the gasket off ...

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

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

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

This bolt goes on the D K side ...

The undersides of the venturis ...

With the venturis out ...

I took this out next ...

With the venturi gaskets off ....

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

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

2+2GT · Feb 13, 2011

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 · Feb 13, 2011

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 · Feb 13, 2011

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:

2+2GT · Feb 13, 2011

BlackVert said:
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 · Feb 13, 2011

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.

2+2GT · Feb 13, 2011

Here ya go:

BlackVert · Feb 14, 2011

2+2GT said:
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 · Feb 14, 2011

BlackVert said:
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 · Feb 14, 2011

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 ...

Realmongo · Feb 14, 2011

I had my carb rebuilt by www.ponycarburetors.com you can buy parts from them too.

What is the set of numbers stamped on the side of the left front toe?

2+2GT · Feb 14, 2011

BlackVert said:
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 · Feb 14, 2011

The check ball that fell out of the power valve line when i turned the carb over.

PN C5AF F

From below ...

Back side underneath ...

Front side underneath ...

Secondary vacuum tube ...

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 ...

Another angle of it ...

horseballz · Feb 15, 2011

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

2+2GT · Feb 15, 2011

Now that's a better angle on the tube. It is quite bent, but surprisingly, ends up in about the right spot.

Realmongo · Feb 15, 2011

The C5AF-F carburetor is about 600 CFM and was used on full size 1965 Fords with the 352 engine with automatic transmission.

ponch0v · Feb 23, 2011

Try this link:

Ed's Carburetor Forum. Carbs rule!!!!

Great FOMOCO carb info

Rebuilding an Autolite 4100 carb

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