2100/4100 mods/tricks

2100/4100 mods/tricks

Joined: August 16th, 2006, 5:30 pm

September 25th, 2007, 2:13 pm #1

Does anyone have any idea of what kind of modifications Pony Carbs does to 2100s/4100s when they rebuild them to make them better than new? Are there any kind of tips/tricks we can do to a 4100 during a rebuild to make them perform better?

Thanks
Howard
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Bill White
Bill White

September 26th, 2007, 5:35 am #2

For the best question ever!!!!!

For the last 6-8 years I have been wondering this same thing about Pony's and as of late a few of the other "carburetor specialist" who "advertise" making modifications to "improve" the 2100/4100.

I have actually had two of Pony's carbs apart (we won't go into that) which VOIDS their really good warantee, and have not seen any visual id of modifications performed. (which doesn't mean they have been done, I might add). I have talked to Jon (the owner of Pony's) and even one of his former employees, but both are mum as to what they actually do as for as modifications. (one because he cited propietary business procedures (Jon) and the other out of professional courtesy since Jon helped him get started in the carburetor business (and since he now also does a significant internent business advertising the (no doubt) same modifications).

I can tell you when I do a regular stock rebuild what I do that I would consider over and above your average rebuild, but there is no "trick" to it.

Firstly, and above all else, I make sure the carburetor is the correct carburetor for that intended application and it has the correct parts installed. Most all of the problems these professionals, claim to fix can be caused by having the incorrect carburetor installed. Change the carb to the correct application viola, problem gone. Same goes for when bench stting it or having the correct jetting and setting. If it is set wrong of has been "modified" by a "hot rodder" trying to get something more it can lead to common type problems, which can be esily corrected by simply bench setting them correctly. I see this in about 80% of the 2100/4100 (especially 4100's). A person who has documented this (such as myself or Pony's) can easily see that most problems are caused by incorect application and incorrect settings or tuning. I have seen 4100's with 10 jet sizes larger, I have seen 4100's with mechanical secondaries. Needless to say these were easy "fixes" to restore and correct the problems they came with.

Next, I make sure ALL PASSAGES especially the annular booster venturis are super super duper clean. These are OFTEN BLOCKED even in a just rebuilt carb. I test every annular booster I install, to make sure it will flow both air and fuel through its respective passages. I use a wire welding tip to clean and make sure the passages are clear, then use a special nozzle I have rigged up with the use of regular brake cleaner to make sure the passages flow, I then completely soak all of these parts in an ultrasonic cleaner to get them even more clean. The ultrasonic cleaner uses soundwaves to clean even the smallest passage of anything.

Most every carb I get that someone has tried to rebuild and still has problems with result from either one of these two above problems. Check this forum, same is true here!!!

I then go over every screw hole and retap them out with special machinist taps. Most people don't realize that taps come in two to three sizes for each different thread size and most homeowners taps are the H3 version which cuts the hole the most oversize possible per industry standards. Most machinist taps are of the H1 variatey and provide a chance to clean and dress the threads WITHOUT cutting them oversize. These are what I use. I also deburr the hole tops and then redress all screws or replace any that have the slightest burr or are stripped.

Next I use only quality parts for my kits, and because of that I use only motorcraft kits 99% of the time. Inferior kits lead to vacuum leaks and fuel leaks and even blocked passages.

Next I make sure all the original parts are in perfect condition and fit properly and I spend whatever time to make sure they do, or I replace those parts. I especially spend extra time with the throttle shafts and getting the butterflys to line up perfectly so they will operate smoothly. There is a difference between the primaries and secondaries of the 4100, install them wrong (and you can) and it won't work as well.

The choke area gets special attention from me since this is a high area of moving parts that often bind or will not funtion seamlessly. Many of the chokes are not working properly nor are set properly out there which then requires compensating someplace, which then messes up the balance of the carb.

I then use precision drill bits to measure all my settings, and all my bench settings are very accurate. As stated above my bech setting are correct for each unique carburetor, and only that particular carburetor. I use the stock jetting unless circumstances dictate a change (They most often don't). When I dail in a carburetor I use both a HIGHLY ACCURATE RPM GAUGE that reads fluctuations as small as 10 rpm (its digital) AND a VACUUM GAUGE. Without both you are just guessing.

The above represent what I feel is the highest level of work and one would be surprised that most shops will not do this type of quality.

As far as mods, the 2100/4100 can always have the venturi bowls cleaned up of all slag and casting material left over. I have done this for certain customers although it is not needed for the vast majority of the rebuilds.
Further mods can include individual tuning for the unique individual application, but when I do this it is usually combined with engine rebuild and dyno time, and involves gas anaylsis and testing. Far beyond the scope of most homeowners.
I have also played with the secondary springs for certain customers to fine tune the secondaries to the individual application. Same with accelerator pump timing.

I do make racing 2100 carbs for my racing partner, I basically do all the things that I mention above. The only things I do different for those carbs is put them on a diet with my milling machine and a die grinder. Our rules state that we can do anything to the outside so I remove lots of material from the outside, including the choke assembly. I have dyno'd and flow benched our carbs and found the best amount of material to remove from the choke plate housing (its not all off). I also anodize coat the outside of the carb for aesthetic purposes.
Our rules state we can not do anything to the interiors of the carbs so......... I really don't mess with that......too much. I do clean up the slag/extra casting material and very, very carefully blend it in since we cannot do anything to the interior.
I also do make sure fuel can flow sufficiently and nothing impedes it into the carburetor bowl. I also make sure nothing impedes the flow of air into the carb and through the venturis and boosters and through the butterflys.
We are using 1.23 2100's (since I can't find the 1.33's and the 1.23's are READILY available). We have spent LOTS AND LOTS of track test time getting the timing of the throttle opening and opening of the power valve to coordinate with my partners driving style and our track that he frequents. Part of this is playing with the amount of shot that the accelerator pump gives.

One IMPORTANT thing to note, he is running a FULL RACE 351 ENGINE THAT WE ARE RUNNING AT 7600 RPM MAX THROTTLE at one track and 8400 at ANOTHER, we are using a 1.23 carb designed for a 1968 ford truck with a 352/390.

SO the weight of his car is approximatley the same as the original application (68 truck) and the cubic inches are very close to the same requirements as the original 351 versus 352/390). Although we are admittedly flowing more than the stock 1.23 356 cfm, and we have changed the shape of the accelerator pump rod and are using a different power valve than stock, OUR JETTING IS JUST ONE SIZE LARGER THAN STOCK. Up until two years ago (when we installed a larger cam as we started running a bit larger track in addition to the one we always run) OUR JETTING WAS STOCK.

I have always been up front about the work I perform. I have to be a bit elusive about our 2100 racing carbs and some of the things I do to make my partner competitive. I owe him that since he is still racing and has to go through tech still and I am his partner. I can assure you it really more comes down to individual testing and lots of time spent in the rebuilding process rather than some super secret cheat. In fact for our carbs I prefer people spent time "looking" for that super secret cheat as they then overlook some of the meticulous and time consuming "cleaning".

Of course I am not "selling" 600.00 dollar carburetor rebuilds based on elusive "I can't tell you or I'd have to kill you" improvements, nor do I "sell" rebuilds on these already fine running carbs claiming to cure everything including the common cold.

There are other things that are pretty common "carburetor tricks" but as a rebuilder of mostly stock and street cars (most all my work is for the concourse and restoration crowd), I find that many of these "tricks" really don't add much for the 2100/4100 carbs and many, many of them detrack or can cause reliability issues later (such as slabbing and thinning throttle shafts and butterflys) and should never be done for the street or at the level I play at. (maybe if I was in NASCAR....... :o) racing for the big bucks)

SO Howard, Thats basically what I do.

How about the rest of you???? What hot secrets or myths do you do for these carbs?

Common you "cheaters" out there what do you have for us.........anybody want to fess up???

I know you are out there, I have a bunch of your carbs that have come off of cars with some of your homebrewed modifications. :o)

Tell us what you have done (or a friend has done, thats ok) and why you did what you did? And what made you do that mod, who told you about it in the first place.

I also know several professional rebuilders peruse this forum, anyone of you want to chime in....

Lets see if we can get a good string going on this one.......


Bill White
White Automotive


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Joined: August 16th, 2006, 5:30 pm

September 26th, 2007, 1:56 pm #3

Ed-

Thanks for that reply. Since we are talking carbs and calibrations/specs, I have this question--you say it is best to ensure the carb is used in the correct application, then also ensure that it is rebuilt and setup for the correct application. Short of differing venturi sizes (1.08 vs 1.12--small block vs big block) and different jet sizes, what else is changeable with the carbs? Can the boosters be any different between carbs? What/who decides what particular specification goes on what particular carb?
Here are the settings i can think of:

float level
jets
choke cap settings

what difference in settings are there between auto trans and manual trans? and why?

Howard
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Bill White
Bill White

September 28th, 2007, 4:43 am #4

Each and every (and theres about 120 +/- variations of 4100's) carb will have its own or share a set of specifications for several carburetors based upon whether its a 1.08 vs 1.12, differing boosters, and differing air bleeds and idle discharge slots.

Ford engineering has determined the variations of the 4100 based on what the expectation of the carb and the application, They are the ones who also established the settings for all the carburetors. Those various settings have been published (or republished) in various places.

The original place those settings were found is in the original equipment specification books, small books that all ford approved (dealership) mechanics got every year from the dealership. These same settings were also found in the original equipment shop manuals.

All good repair kits will have a copy of the specifications in order to bench set that particular carburetor. One of the problem with cheaper kits is they do not contain this or contain faulty or incomplete specs.

You definetly do not want to be "interchanging" parts such as venturis and willy nilly replacing jetting since these are two (of the many) of the fastest ways to disrupt the carburetor settings. Same with using specifications that are intended for another car or a hodge podge of specifications.
(For example using a 66 mustang specs because you think that will give you more pep for your 61 galaxie, the 61 galaxie carburetor is intended to work perfectly with those 61 galaxie specs, by changing to the 66 mustang specs (different variety of the same carb) will cause that 61 carb to act differently and throw it out of balance.)

The reason is the WHOLE carburetor works in conjuction with itself, that particular carburetor has unique idle disharge ports, unique air bleeds, which work with a given set of boosters and a given set of jetting and the various settings, any of those are different and the whole ratio of air to fuel changes and the whole timing of the air/fuel ratio can be disrupted.

Think of it as a cherry pie, when baking if you add less sugar, you still have a cherry pie when your done but it will taste completely different, how about more baking powder or more butter...... Get the idea.......

Now some changes are minor and will not disrupt the carb as much, like for example going 1 or 2 jet sizes bigger. Adding two jet sizes will disrupt the flow but minor enough that it just changes the timing of the air/fuel mixture. More than 2 ets sizes will throw if off significanlty more, maybe not enough for you to notice but I can assure you 3 jets sizes (or more) will show on on a dyno and an air fuel meter. That is why you always hear me talking about NEVER going more than 2 jet sizes. It is my believe (after testing on the above machines) that 3 (or more) jet sizes will throw your carb out of Stoic. (fancy way of saying more than the 12.5-14.5:1 air fuel ratio that the carbs were originally set up for)

The other problem with mixing and matching is if there was some sort of table or data that showed ALL OF THE MANY VARIATIONS AND WHAT THOSE EXACT VARIATIONS for each carburetor and how they INTER-ACTED with each other, then one could logically start switching and swapping pieces for what ever idea they were looking for.

BUT unfortunatley no such information exists from either AUTOLITE nor from FORD.
Trust me I have spent 15 years looking for this information as its the HOLY GRAIL of carburetor info.
I have talked to several mechanics/people who claim to have this info and after talking to them I am certian they have no information that was ever published from either FORD or AUTOLITE. Some of them have been outright frauds or mistaken information.
I have talked to 2 mechanics who I am certain have in their possesion some of this information that they have inquired from their own independent research. How much of the data and how accurate it is remains to be seen. And whether these two can fully use that information and how it applies as each variant acts upon the other also remains to be seen.
How complicated can it be, Just looking at the venturi annular booster for the 2100/4100 it can have over 14 differing measurements for each set of boosters. How does any one of those 14 differing items effect how that booster flows??? And what changes need to be done when any one of those 14 items change???
Remember I am talking scientific analysis and accurate test results rather than swapping parts and getting lucky.

When I was unable to find this type of data, That is when I started to research to create my own, (I had both the time and proper equipment to do this at that time) but the project became UNOBTAINABLE with little to show.

Hope that helps and was what you were looking for.

Bottom line, either get the correct carburetor for your application, or when not possible (like swapping) obtain a carburetor that MOST closely matches your application (with the 2100/4100 that is not all that difficult). Then rebuild it to the CARBURETOR NUMBER/Application that it was originally intended for.

I gave the example of my partners race car, all of those carbs that we use are C8TE-A or B carbs, or 1968 ford truck carbs with a 352-390. Basically the truck is very close to the weight/style of our race cars (heavy front ends/light rear ends and about 3500lbs), and the engines are of like cubic inches (351 vs 352/390) and although the 352/390 FE could use more CFM than our small block 351 our race engine is revving more (lot more) and has more volumetric efficiency than a stock 351.
I still rebuild and use the 1968 ford truck stock specifications for these carbs and we are presently using 2 jets sizes larger than stock. (like I said before we were only 1 size larger before we installed a MUCH LARGER CAM to run on a larger track as we needed more duration on the bigger track). The cam we are running is a full out race cam that WOULD NEVER SEE THE STREET.


Bill White
White Automotive

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Joined: August 16th, 2006, 5:30 pm

September 28th, 2007, 1:00 pm #5

Thanks Bill for that info. I wasnt aware that there were so many differences between carbs

Howard
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Bill White
Bill White

September 28th, 2007, 4:57 pm #6

They all have different numbers. Even though they are all 4100's, they are truly unique to the vehicle application which is based upon vehicle weight and size, engine cubic inch and volumetric efficiency, intended RPM range, emission type and transmission type.

Now again some of these ae blurred, (like a 60 thunderbird carb for a 352 is completely different than say a 65 galaxie carb 352/390) and when swapping probably wouldn't notice much of a difference (only on a dyno).

But others carbs having similiar identities can cause much confusion. (like a 66 california emission thunderbird carb #6 S C and a 66 mustang 6 Z B, Both are 1.08 1966 carburetors but one is intended for a heavy FE (428) powered car and california emissions and the other a very light 289 powered car).

Again there are over 120 differing varieties of 4100's spanning 10 (actually 13) years and at least that many or more of the 2100's which spanned over 20+ years if you count the 2150 model. At least the 4100's only have 3 types of venturi sizes whereas the 2100 has 8.


Bill White
White Automotive
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Paul
Paul

October 1st, 2007, 8:59 pm #7

Hello Bill

When Can I get my Oval track Carb?

I have a 1.23 from a 74 Cougar 351C. In fact it is still the 351C sitting in the back room.

I don't know if it is still good. As you know, I also have the 64 1.33
I need a good carb. As my 1.21 took a sh!!.

I race on a 1/2 mile asphalt Oval. I only get about 6000 to 6500rpm
351W 8.5 compression, 74 Factory intake & 87 Mustang exhaust Manifolds.
Stock lift((.446) & 124 duration @50 non-roller.

I have a 7448 Holley. Runs like sh!!. Will idle until I get her on the track. Then the Chug Chug starts. Black smoke. Think its the power valve.
I borrowed a 4412 & she was running hot. He said it have 72-74 jets in it.

Paul
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Joined: June 27th, 2003, 1:50 pm

October 3rd, 2007, 2:20 am #8

Hello

The correct cam numbers are .466 lift & 224* @.050 duration

Paul
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Joined: May 11th, 2008, 3:44 pm

February 24th, 2009, 12:38 am #9

i've been doing a little reasearch on modifying the 4100 myself for a couple years now and have found an old 70's drag racing magazine that has an article on super tuning the 4100 and recommends replacing the stock needle and seat assemblies with those from a carter (afb i think), holley secondary spring kit, holley power valves (i may try some QFT 4 window valves), holley (or ford) jets and playing with the accellerator pump arm settings, plus a few other minor things i can't think of off the top of my head. the article claims as much as a full second or more in 1/4 mile times plus a few MPH if properly done.

also Summit has now come with their own version of the old holley 4010 and has made some improvements such as tunable venturi clusters, which i understand are interchageable with the 4100, and i plan on eventually ordering a pair of boosters and the idle and high speed restrictor bleed kits to do some experimenting with a 1.119 4100 i have and see what kind of gains i can get from it but more importantly i plan to optimize the 1.19 to my 351w which will have a mild hydraulic roller cam, aluminum GT-40 heads, nice flowing exhaust with either heavily massaged and ported stock manifolds or shorty headers and mandrel bent 2.25" exhaust, i may go up to to 2.5" but i prefer the 2.25" because it's much quieter and this will be in my mild sleeper 69 cougar so i want the exhaust quiet enough to not give anything away or annoy the piss outta me on the freeway.

as of yet i haven't put any of these mods into effect but i wanted to put this out there and get some opinions from the experts.
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Dave H
Dave H

May 1st, 2012, 3:33 am #10

Each and every (and theres about 120 +/- variations of 4100's) carb will have its own or share a set of specifications for several carburetors based upon whether its a 1.08 vs 1.12, differing boosters, and differing air bleeds and idle discharge slots.

Ford engineering has determined the variations of the 4100 based on what the expectation of the carb and the application, They are the ones who also established the settings for all the carburetors. Those various settings have been published (or republished) in various places.

The original place those settings were found is in the original equipment specification books, small books that all ford approved (dealership) mechanics got every year from the dealership. These same settings were also found in the original equipment shop manuals.

All good repair kits will have a copy of the specifications in order to bench set that particular carburetor. One of the problem with cheaper kits is they do not contain this or contain faulty or incomplete specs.

You definetly do not want to be "interchanging" parts such as venturis and willy nilly replacing jetting since these are two (of the many) of the fastest ways to disrupt the carburetor settings. Same with using specifications that are intended for another car or a hodge podge of specifications.
(For example using a 66 mustang specs because you think that will give you more pep for your 61 galaxie, the 61 galaxie carburetor is intended to work perfectly with those 61 galaxie specs, by changing to the 66 mustang specs (different variety of the same carb) will cause that 61 carb to act differently and throw it out of balance.)

The reason is the WHOLE carburetor works in conjuction with itself, that particular carburetor has unique idle disharge ports, unique air bleeds, which work with a given set of boosters and a given set of jetting and the various settings, any of those are different and the whole ratio of air to fuel changes and the whole timing of the air/fuel ratio can be disrupted.

Think of it as a cherry pie, when baking if you add less sugar, you still have a cherry pie when your done but it will taste completely different, how about more baking powder or more butter...... Get the idea.......

Now some changes are minor and will not disrupt the carb as much, like for example going 1 or 2 jet sizes bigger. Adding two jet sizes will disrupt the flow but minor enough that it just changes the timing of the air/fuel mixture. More than 2 ets sizes will throw if off significanlty more, maybe not enough for you to notice but I can assure you 3 jets sizes (or more) will show on on a dyno and an air fuel meter. That is why you always hear me talking about NEVER going more than 2 jet sizes. It is my believe (after testing on the above machines) that 3 (or more) jet sizes will throw your carb out of Stoic. (fancy way of saying more than the 12.5-14.5:1 air fuel ratio that the carbs were originally set up for)

The other problem with mixing and matching is if there was some sort of table or data that showed ALL OF THE MANY VARIATIONS AND WHAT THOSE EXACT VARIATIONS for each carburetor and how they INTER-ACTED with each other, then one could logically start switching and swapping pieces for what ever idea they were looking for.

BUT unfortunatley no such information exists from either AUTOLITE nor from FORD.
Trust me I have spent 15 years looking for this information as its the HOLY GRAIL of carburetor info.
I have talked to several mechanics/people who claim to have this info and after talking to them I am certian they have no information that was ever published from either FORD or AUTOLITE. Some of them have been outright frauds or mistaken information.
I have talked to 2 mechanics who I am certain have in their possesion some of this information that they have inquired from their own independent research. How much of the data and how accurate it is remains to be seen. And whether these two can fully use that information and how it applies as each variant acts upon the other also remains to be seen.
How complicated can it be, Just looking at the venturi annular booster for the 2100/4100 it can have over 14 differing measurements for each set of boosters. How does any one of those 14 differing items effect how that booster flows??? And what changes need to be done when any one of those 14 items change???
Remember I am talking scientific analysis and accurate test results rather than swapping parts and getting lucky.

When I was unable to find this type of data, That is when I started to research to create my own, (I had both the time and proper equipment to do this at that time) but the project became UNOBTAINABLE with little to show.

Hope that helps and was what you were looking for.

Bottom line, either get the correct carburetor for your application, or when not possible (like swapping) obtain a carburetor that MOST closely matches your application (with the 2100/4100 that is not all that difficult). Then rebuild it to the CARBURETOR NUMBER/Application that it was originally intended for.

I gave the example of my partners race car, all of those carbs that we use are C8TE-A or B carbs, or 1968 ford truck carbs with a 352-390. Basically the truck is very close to the weight/style of our race cars (heavy front ends/light rear ends and about 3500lbs), and the engines are of like cubic inches (351 vs 352/390) and although the 352/390 FE could use more CFM than our small block 351 our race engine is revving more (lot more) and has more volumetric efficiency than a stock 351.
I still rebuild and use the 1968 ford truck stock specifications for these carbs and we are presently using 2 jets sizes larger than stock. (like I said before we were only 1 size larger before we installed a MUCH LARGER CAM to run on a larger track as we needed more duration on the bigger track). The cam we are running is a full out race cam that WOULD NEVER SEE THE STREET.


Bill White
White Automotive
Bill may forms of energy interst me , right now , its all eitheric.
anyway is it important to get the 4100 idle low enough to reduce
distributor vacuum to ZERO? if so is it done with secondary shaft
adjustment? Oh. look up Tom ogle fuel story" on line. been over 30 years
since his galaxie got 111 mpg. i got a chance to yak with him in that day

thank for the nice and well thought out post.
Dave .
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