Carb Replacement

[ozbird]

Hi,

glad you are enjoying the updates, check this WWWlink, on our very own forum... It is a standard factory item, may have been tossed away by some unknowing previous user.

viewtopic.php?t=6836&start=45


Graeme

[stevegintn]

Hi,

glad you are enjoying the updates, check this WWWlink, on our very own forum... It is a standard factory item, may have been tossed away by some unknowing previous user.

viewtopic.php?t=6836&start=45


Graeme

Wow - thanks, Graeme - I'm not sure what to make of all that? (a picture is worth a thousand words)

But I did retrieve this great photo of the kickdown assy for reference (haven't looked at it lately, but am missing *some* of it)

[stevegintn]

P.S. Here are a couple photos someone had already shared with me, of how it's SUPPOSED to look, and the third is what I have (looks like I'm missing the short rod that goes perpendicular to flat bracket on intake?). When I got my car back from the engine rebuilder last summer, the dashpot was GONE (but with new carb, won't need one - right?)

[ozbird]

Great Steve - I can see from your image that all your parts for the kickdown are in place but not connected.

Your mechanic has left the short rod floating but you just need to bolt it back to the throttle rod closest to the firewall. It attaches with a nut an bolt which should be still intact. There is a small hole under the top connection which is used for the carb actuation.

Once that is done check the springs are in the correct location and you are good to go.

You can get a Holley solenoid if you need one, maybe not if you don't use air=con much if at all.

P. S. Looks like accelerator rod is in wrong location, should be on top.

Enjoy,

Graeme

[MN63Tbird]

Interesting that everyone is jumping ship from the Autolite 4100. They made a good carb that many lasted years in Tbirds and Mustangs through the 60s. It is as mentioned a little finicky to get all tuned in but one everything is in place it does work. A couple items that were never mentioned were the power valve rating, jet sizes and choke travel. Power valve for an 18" vacuum should be a 9.5". Most rebuild kits come with a 7.5"Hg unit. Check withe Mikes Carbs to confirm if you like. The Jets should be 52 and 66 but over time they will wear so should be replaced. The primary could go up in size due to elevation you drive at and if you run ethanol based premium vs non oxy. Finally the carb spring does wear out over time. My experience shows it needs to travel at least 13/16" from cold to hot to give a good balance of air to fuel as the engine gets warm. The whole flat spot seems to be an incorrect balance of air to fuel as the car accelerates or gets warm. Each of these items also affects that mixture under load. These are cheaper fixes to try than purchasing a new carb and still keeps the Tbird stock. Just my thoughts

MN63

[Karl]

G'day - thought I would throw my 2 Bob's inn - for what it is worth.

I would have to agree with MN63, I think the autolite is a good carb, there must of been millions of them made throughout the 60"s and they did the job. I have rebuilt a couple, and at the moment I am in the process of having oversize shafts fitted to one of them to stop air leaking in.

The choke would be a problem, to get the air fuel mixture right as the engine warms up can be a drama, you would only want a few items to be out of whack and it is not going to function as it should be. You can't really compare a modern day car with a carburetor, with a modern car there is a computer which is constantly measuring gasses, temperature, revs, fuel and the like just to to keep it running. There is nothing on a carburetor to do this.

I can understand why people opted out and purchase a aftermarket carb, it is a lot easier and the end result is no heart ache when you go for a drive, which lets face it is what we all want. Personally I prefer the Autolite, it keeps the car original, and yes I have put a lot of time in to learn how they work. Also a lot of trial and error in fixing them. I would like to see how a new aftermarket carb is after 50 years and 1/2 a dozen backyard mechanics working on them would be like.

As MN63 said with the fuel that we have today you may have to change the jets around a bit to get the right colour in the exhaust, although I think you may have the jet size the wrong way around, the higher you go up the smaller the jet is. I think this is because there is less oxygen the higher you go, so therefore you have to have less fuel.

As for the flat spot, yeah these can be a real pain, what fixes one carb probably won't fix the next one. What I try to do is figure out what has been done to the carb in the past return it back to original and then try to fix it.

As I said before, just my 2 bob's worth.

Here is a brain teaser for you:-
I am trying to work out the part number for the screw that holds the choke housing cover onto the Autolite carb. (there is three)
The 1960-1964 Master Parts Catalogue (illustrations) calls the screw 26576-S (the S is the finish ie zinc or cad or whatever) Page 325.
The 1960-1964 Master Parts Catalogue (text) calls this screw 26576-S7-8 (the S-7-8 is cadmium or zinc plate). It also states it is a #8-32 x 5/8" Fillister head. Page 564.
Also it says that a flat washer and spring washer is to be used.

Now all of the carbs that I have seen have the spring washer attached to the screw. Not separate. So Ford changed this?

According to the AMK products, Inc book "Guide to Ford Fasteners 1955-73" the 26576 is a round headed screw not a fillister head screw. It also doesn't have a spring washer attached.
In the AMK book there is no listing for a fillister screw 1-5/8" long, whether it has a spring washer attached or not.
AMK do sell a replacement screw but it is 1-3/4" long and it has a Ford part number of 378547. (this is on there page 92 of their PDF catalogue in their web pages. It matches with their book.
Now I can understand them selling a longer screw and that's fine, but the part number?
I think I will go with the Master Parts Catalouge number.

Oh I don't have to much spare time on my hands either.

Karl.

[ICON 1956]

Wow Karl ! you sure did your home work, We are lucky to have you on this forum....

[MN63Tbird]

Karl, dont know if this helps your part number search but here are photos of the screws from when I rebuilt the 63 Tbird 4100. The screws,spring washer and setup is identical to my 66 Mustang with a 4100. I compared this to the photos I had of that carb. Both cars had numbers matching carbs so they are original to the cars.

You may be able to get an idea of the screw length from the photos. My Tbird is in a warm storage a few miles from here so I cant access it to measure the screws.

Hope this helps.





As for setting up the carb correctly it is a tricky manner. I don't recommend making multiple changes at once. You don't know which change worked or did not. I set up a test sheet to make one change then check out how the car starts warms up and runs. I would record all the engine data I could and engine temp with my IR thermometer as well as watching the gauge in the car. After that test I make the next change. It took me 6 trials over 3 days to get the choke spring setting just right for starting a cold engine to make it run smoothly as it warmed up and would do it consistently. It kept trying to die just before it was fully warmed up if I gave it the gas. The usual problem was after I drove it about a mile to a stop light, sitting there until the light turned green and then hit the gas and it would stall. Figured it out though. Had to be the right lean setting and right spring tension for the choke to allow the correct air in for that temperature of the gas/engine.

MN63

[Karl]

Thanks for your help MN63.
I agree with doing one change at a time. Otherwise you never know what made the changes.
Screw length is not a problem as I have a few old carbs and I can compare the screws, also the MPC in most cases gives you the size and length of the screw.
With regards to your photo's I like the idea of the bolt and nut set up in the mounting plate to keep the carby steady whilst working on the carb.

The 3 screws that you have in the second photo is not the one's that I was referring to. I did give you the wrong description, I should of said, "Choke housing onto the Autolite body". It is the 3 behind. The one's that hold the choke housing onto the main body.
If you are looking to replace the 3 in your photo because the heads a worn here is a link to AMK's web page, only problem is you have to either purchase 250 or 500. I can find on their web page on says $30.00 for 250 and another says $30.00 for 500. Ford part #31061-S8 or AMK part # B12271.
https://www.amkproducts.com/Catalog_PDF/92-108.pdf
https://www.amkproducts.com/bulk2.asp?c ... ister+Head Click on the image of the screw.

Karl.

[stevegintn]

As for setting up the carb correctly it is a tricky manner. I don't recommend making multiple changes at once. You don't know which change worked or did not. I set up a test sheet to make one change then check out how the car starts warms up and runs. I would record all the engine data I could and engine temp with my IR thermometer as well as watching the gauge in the car. After that test I make the next change. It took me 6 trials over 3 days to get the choke spring setting just right for starting a cold engine to make it run smoothly as it warmed up and would do it consistently. It kept trying to die just before it was fully warmed up if I gave it the gas. The usual problem was after I drove it about a mile to a stop light, sitting there until the light turned green and then hit the gas and it would stall. Figured it out though. Had to be the right lean setting and right spring tension for the choke to allow the correct air in for that temperature of the gas/engine.

MN63

MN63, that's a very methodical, scientific approach to solving the problems - but jeez, does it have to be that difficult?

I have worked on my '62 for the past 2 1/2 years, finally got her running and stopping, but driven very little. I just want to get the hard-starting issue resolved, so I can take her to the paint & body shop (without being embarrassed).

The ONLY reason I am considering the replace the Autolite 4100 is due to the non-starting issue from bad choke. When I picked it up from the engine builder last summer, it started if your just TOUCHED the key. After I got home and later did a little investigating, I discovered the builder had WIRED THE CHOKE PLATE TO A FIXED POSITION (warm-weather starting only). Btw, the builder also left my kickdown disconnected and the dashpot GONE. After I removed the wire, I discovered that the choke was still not working properly. I replaced the choke with an old one from my '61 parts car, and numerous efforts at adjusting have failed.

So at this point, I am about all out of PATIENCE trying to get old technology to work?

Somebody had told me previously, that's there's an aftermarket electric choke that will solve the problem. So I will try that, before tossing the Autolite. Does anybody know offhand, who has that electric choke?

Thanks, guys, for all the feedback!

[stevegintn]

P. S. I did a quick search and found the conversation we had last summer, on my first efforts at resolving the 'wired choke' issue.

viewtopic.php?f=6&t=15309&p=91685&hilit ... oke#p91685

You can see there, Mr Bill Logue told me that he had gotten an electric choke from Champion Carburators that is working for his car, so I will check there first.

[stevegintn]

Here's the replacement electric choke kit that Champion sells: http://www.championcarburetor.com/5864- ... 10711.html

Bill Logue, is that the one you recommend?

[MN63Tbird]

Steve, Years or running technical tests at work led me to do the same effort on this issue. Normally I am not that methodical working on my cars but in this case after stalling at intersections a couple of times and having to wave people around until I could get the car started frustrated the heck out of me so I decided to do the more scientific methodical approach. The effort took a lot of time since I had to wait for the car to cool down after each trial to check out the choke again so I typically got only 2 tries a day. I would start the car and record RPM, Temp and throttle plate opening. I would watch the temp gauge move and at certain spots ( I had 5 spots identified on its travel) I would go out do a quick measurement on conditions then give the car gas. If it stalled it was a failure. I would restart if possible and finish out the test doing the same giving it gas at the next spot on the increased engine temp and see if it would stall. I would then have a profile for where it would stall over the complete warming of the car. Each choke had a different profile also where I set the lean/rich setting to start would also have an impact.

I had 3 chokes to test, #1 opened at 3/4" (the original in the car) , #2 opened 1/2" - a new unit and #3 opened 13/16" another new unit . I put each into hot water to see how far the spring would open from cold to warm and measured the distance. If you note #1 and #3 are quite close in distance but the #1 choke was much slower to respond to the hot water. I found the 13/16" worked the best throughout the full range of RPM. That also happened to be the last choke I tried so again it took a few days to get to that.

The whole choke/gas thing is trying to get the correct fuel to air mixture as the car warms up. As the engine block gets hotter the fuel into it becomes more volatile so needs less air to ignite it. The choke is trying to match the air intake with the temp of the engine and volatility of the fuel. The spring is just a mechanical method. You need the correct spring and tension to match your car. This set up for an Autolite 4100 was used for almost a decade so I knew there had to be a correct combination of settings. Todays fuel injection with an O2 sensor for feedback and a computer doing the calculations does a much finer job of doing that task.

MN63

[bbogue]

Here's the replacement electric choke kit that Champion sells: http://www.championcarburetor.com/5864- ... 10711.html

Bill Logue, is that the one you recommend?

Steve,
Yes, that’s the one. It did not have the loop in the end of the spring which I did with needle nose pliers and I used several gaskets but these were the only issues. When I called them Champion offered to bend the spring for me but I would have had to return it so I did it myself. No big deal. I wired it to a power buss tht is powered off the ignition switch. Good luck. My last name is Bogue, by the way.

Bill

[Alan H. Tast]

Steve, Years or running technical tests at work led me to do the same effort on this issue. Normally I am not that methodical working on my cars but in this case after stalling at intersections a couple of times and having to wave people around until I could get the car started frustrated the heck out of me so I decided to do the more scientific methodical approach. The effort took a lot of time since I had to wait for the car to cool down after each trial to check out the choke again so I typically got only 2 tries a day. I would start the car and record RPM, Temp and throttle plate opening. I would watch the temp gauge move and at certain spots ( I had 5 spots identified on its travel) I would go out do a quick measurement on conditions then give the car gas. If it stalled it was a failure. I would restart if possible and finish out the test doing the same giving it gas at the next spot on the increased engine temp and see if it would stall. I would then have a profile for where it would stall over the complete warming of the car. Each choke had a different profile also where I set the lean/rich setting to start would also have an impact.

I had 3 chokes to test, #1 opened at 3/4" (the original in the car) , #2 opened 1/2" - a new unit and #3 opened 13/16" another new unit . I put each into hot water to see how far the spring would open from cold to warm and measured the distance. If you note #1 and #3 are quite close in distance but the #1 choke was much slower to respond to the hot water. I found the 13/16" worked the best throughout the full range of RPM. That also happened to be the last choke I tried so again it took a few days to get to that.

The whole choke/gas thing is trying to get the correct fuel to air mixture as the car warms up. As the engine block gets hotter the fuel into it becomes more volatile so needs less air to ignite it. The choke is trying to match the air intake with the temp of the engine and volatility of the fuel. The spring is just a mechanical method. You need the correct spring and tension to match your car. This set up for an Autolite 4100 was used for almost a decade so I knew there had to be a correct combination of settings. Todays fuel injection with an O2 sensor for feedback and a computer doing the calculations does a much finer job of doing that task.

MN63

You can swap parts to "plug-and-play," but in the end there are ways to figuring out what's wrong, what needs to be refurbished or tweaked, and be able to restore proper operation. MN63's systematic approach (albeit time-consuming and lacking the instantaneous gratification that swapping an old part out with new will provide) hits the nail on the head on how to approach adjusting and tuning a rebuilt carburetor or diagnosing a bad one.

In reality, there aren't that many parts to wear out on a Ford/Autolite 4100 - throttle shafts/bushings, which can be replaced and reworked to bring them back to OEM tolerances (most people don't realize this!), choke linkage/bushings, return springs are the main mechanical items that would see wear. The power valve, accelerator pump diaphragm and needle/seat are usually replaced with a rebuild, and the larger diaphragm on the bottom of the carb that's usually not included with today's rebuild kits that you have to buy separately. With the changes in gas formulation for today's needs, though, knowing the effect on jet sizes needs to be better understood. But, more than anything else, understanding the basic physics of how carbs work to bring together the balance of fuel and air is a necessity, as is basic troubleshooting procedures.

In this day and age, it's easier to swap things out that to take the time and effort (or have the patience) to troubleshoot or methodically go through a decades-old part. I'm guilty of that at times, but I applaud those who attempt to "keep 'em flying" and retain the original equipment that combines to make such efforts stand out in the crowd.