That's amazing! Years ago, I talked to Jon by phone when Pony Carburetor was still in NY. He had the answer to a problem I'd had for years that nobody in my AZ chapter of Vintage Thunderbird Club including our tech advisor knew anything about. After running at highway speed, my carb would flood itself--fuel gushing down the primary venturies when I came to a stop, eventually stalling the engine. He explained that in the manufacturing, Ford left out a machining step on some of these carbs at the factory. The Venturi assemblies are supposed to have some tiny anti-siphon air bleed vent holes. The manual for my '66 Thunderbird clearly shows the vent holes and identifies them. However, looking at mine, they're not there. I got one of the units where they missed machining them. My carb was siphoning fuel after a high vacuum running condition because of it. He said when they re-engineer one of these carbs, they add those vent holes to eliminate the problem. I asked him how he can drill a hole that small in diameter, there are no drill bits that small and he laughed, said it's a trade secret. If I could add photos here, I have one of my venturi cluster and the illustration in the manual. Nobody else I've talked to is aware of this issue.
So *that's* what those little tiny holes are for! I was wondering about that when I put my carb back together after cleaning everything... They didn't look like they were actually connected to much of anything...
Thank you so much! This video was so clearly shot and your instruction & examples so easy to follow along! Just got my car from no idle to running in gear, thanks again.
Just finished rebuilding the carb on my '68 Galaxie 390 -- this video will come in *very* handy when I get ready to install the carb and get it running. Thanks so much!
thanks for the info. and being a nice person and trying to help I will try passing this on to some one else who may also need help thanks again and have a great day lynn
We used to replace those carbs with a Holley because the secondarys would hang wide open when you pushed it to the floor. We were afraid to kick it wide open. You would have to take it out of gear and turn off the engine to get it to stop. I realized as I got older that it was because the white plastic rod that helps push the secondaries closed would break off. I only owned one out of many that still had that rod intact. I thought that the white piece of remaining plastic was there to keep the screw behind it tight. I think that every rebuild kit for these carbs should come with a new nylon secondary shut off pin. I have bought a lot of different rebuild kits for these carbs and none of them had one. I put a screw with just enough threads to hold it in, in that position now. You should address this in one of your videos.
Probably the best video regarding the 4100. Here's my issue. Car starts and runs fine. When pulling up to a stop sign I can feel the engine running to fast. Put it in neutral tap the gas the engine returns to it regular idle speed. Start driving again, next stop sign, same issue. You would think the choke plate had closed but it isn't it's wide open. I've checked each time when the idle is to fast. I think perhaps the fast idle linkage is hanging up or it way out of adjustment. With all the adjustment required where would you start? Or is it another part of the carb that could be causing this? Thanks
Hard to say, could be the throttle is sticking somewhere other than the carb. Best to just go through all the adjustments in the video start to finish.
I like this video! Had my 4100 "rebuilt", restored a couple years ago by a guy who used to work for Pony Carburetor. It looked great but has a couple problems. My fast idle cam isn't moving into position when the choke is cold (closed) but my worst problem is that on a cold start, fuel floods out of both carb vents on top of the bowls. Lots of fuel! I've checked the float levels and they're right where they should be. If those needle/seat valves are closed, how is fuel getting past them to overfill the bowls?
The one in the video is a Pony rebuild the late Jon worked on FYI. :) If you have overflow problems, I would check fuel pressure first to make sure it's not excessive, especially if you have an electric pump or regulator in the system. I think 6.5 psi is the max spec. Otherwise fuel should not overflow if the floats and needle valves are working. Make sure the floats are bent correctly so they are level when the fuel level is at the correct height. Needle valves can also stick open/closed if they varnish or the seats get old and sticky. May need to clean and replace. Fast idle cam should be completely loose and free moving with the choke cap off and the throttle opened, perhaps it is sticking or something got bent. It should fall into place by gravity when the throttle is opened.
Thanks for the info. Before I saw your reply, I checked my choke linkage and adjusted the fast idle cam adjustment screw on top. It was way out of adjustment and not making contact with the stop. Using your adjustment video info, I set it up accordingly and it worked great. My fuel pump is OE type, not electric and I replaced it while the carb was off the car being "restored". It's the style with the filter canister integral with the pump. Could that pump output pressure excessive enough to overcome closed needle and seat valves?
I wouldn't make assumptions and would just test the fuel pressure with a gauge. Perhaps the mechanical pump isn't performing to specs. High pressure will push open the needle valves. They could also not be sealing.
yes sir wrote you awhile back and you helped me out with info. on how to make a check ball weight for my 4100 carb got it fixed and the weight works fine but started having another problem to make a long story short the car wont run with the choke all the way open I though vacuum leak but could not find one but instead I did find a crack in the carb right under the mounting bolt of the choke toward the front of the carb I don't know if I cracked it when I tighten it down or it was already there it looks like it is next to a casting seam is there any way to fix this or is it junk the only thing I can think of would be something like jb weld do you think this will work it is really a small crack thank you for your help
Try spraying carb cleaner on the crack while it's idling to verify that it's a vacuum leak. If it is a leak and you've tried a new gasket, then you can try hi-temp RTV sealant on it. If engine is fully warm, you're sure there are no vacuum leaks, and it doesn't run without choke being closed some, then you should check the timing and the idle mixture adjustments. But vacuum leaks are the most common cause (check all lines and upper/lower intake manifold gaskets too). Crack doesn't sound good, might get bigger with thermal cycling. Might have to junk it if it's leaking internally.
thanks for the info. I will double check everything for vacuum leaks all the hoses has been replaced and could not find any leaks around the intake or carb mounting flange the crack I mention is right in the center of the carb body side right below the top mounting screw for the choke it is a quarter of an inch cross but the crack run out 3 different directions almost like it has been punched with something it is also discolored around the crack a faint gold color that is what made me notice it like some one has tried to repair this crack before I happened to shine a blue light on it and it high lighted the area then I could see it real good thanks again for all your help
i found replacement choke housing in my junk pile on an old 2100 ford carb. th piston was frozen but i got it moving with some pb blaster and heat. it still is binding a bit at the top of its travel. i know i an knock out the expansion plug at the bottom of the bore and clean oout the lower part. the piston is held in place by a rivet to the choke lever. i think. can i easily get the piston out to really clean out the bore well so there is no binding?. they make replacement explosion pugs for the bottom
the piston is attached directly to an arm/lever that that is held to the choke plate rod by a nut. If you remove the nut, the arm assemply and piston can be pulled out. I had to do this myself to clean the piston and its cylinder. The arm has flats on it, so you cannot put it back together wrong. Before you put it back together, notice that the top face of the piston has a channel,groove across it. Notice also that the cylinder wall has a hole in it. The adjustment requires you to make a hook out of a paper clip, and put the hook end into a hole in the cylinder wall NEAR the top. Now, when the piston tries to travel upward, it will strike that hook in the wall of the cylinder and be prevented from coming any further up. The additional complication is that the paperclip hook needs to not only be hooked into the cylinder wall.... but it needs to be hit by the groove across the top of the piston, and NOT by the top face of the piston.
My autolite 4100 does not have the adjustment at the top of the air horn; the one you mention at the 3:25 mark. What should I do? Ford made many versions of this carb. According to my Ford shop manual - mine is supposed to have a magnet that help close the choke on that air horn and I don't have that either. It is the original carb to the car.
The magnet chokes are somewhat rare, since there isn't an adjustment I think you just skip that one. If the magnet is missing you might have trouble starting the engine if the choke doesn't close fully. Might need to compensate more with the choke cap adjustment so it closes fully before cold start.
@@TechnicalLee Thanks! I ran into another 4100 in my buddies T-bird and inside his choke he did not have the piston pulldown for the choke pull off. His was a spring with an adjustment screw to adjust pull off. Are those better? I have one in my parts carb; seems easier than the paper clip method.
Was following you until you said something about adjusting the bottomed Screw to the "V" but theres no way possible it can touche the V because you have it sitting on that bottom bolt, and the screw is no where near the V.
I assume you are talking about #3 fast idle speed adjustment. First warm up the engine and shut it off. Manually open the throttle a little bit and then move the fast idle cam so that screw is aligned with the V, and then let go of throttle so the screw is touching the cam and sitting on top of the V with hands off. It's hard to see sometimes so you have to get your head under there with a flashlight. Then start the engine and adjust the screw while watching the tachometer until the warm idle speed meets spec. In the video I had the throttle blocked open from the previous adjustment, which is why the screw wasn't touching the cam (I was just showing the marks rather that doing the actual adjustment).
i dont understand what yo hook the paper clip to on choke pulldown. don't you just wan the piston at y the top of its travel? i have a '66 carb, same as your '65 autolite 4100
There's a groove in the side of the cylinder bore, you set the end of the bent paperclip in the groove and pull up until it hits the top edge of the groove. Then move the linkage so the piston is pressing up on the paper clip holding it in place. The idea is to hold the piston in a specific position to make the adjustment. Just bend the paper clip and feel around in there if you can't see it. Piston at top of travel will cause an incorrect setting.
Probably the choke cap adjustment is off. That's #4 in the video. I would go through and adjust everything like I did, and pay attention to how I recommend you set the choke cap around 8:30. If the other adjustments are off that can happen as well (check all the adjustments if you want it to work right).
@@TechnicalLee Thankyou that was exatly the issue now the car idles. But the choke plate doesn't close all the way still , maybe open 1/8"in still and can't seem to get anymore adjustment out of the linkage
@@dustinshenefelt9887 I think if the fast idle cam screw is in too far it might prevent it from closing all the way. Go through and do adjustment #1 and #2 in the video so fast idle cam isn't being maxed out. Also make sure throttle is only open like 1/2 during adjustment otherwise choke unloader will be pushing it open.
yes wanting to ask a question took my 4100 apart to rebuild and discovered that my check ball weight was missing that's in the mane fuel delivery I have heard every one say I can make one but they can not tell me the length of the check ball weight do you know the size of this check ball weight or would you have one you would be willing to sale thanks for any info. lynn
@@TechnicalLee i opened the choke housing on my 66 c6sfc autolite and there is a lever but there is no brass piston connected to the lever. did they make carbs without the piston if so did the choke work properly. there was a swap meet purchase. dont think someone would remove the piston..
@@vermbird8393 I'm not an expert on all the variations, but I would guess that the piston needs to be there. Without it the vacuum choke unloader function won't work and the choke may stay too far closed after engine start, possibly causing a start and stall condition. Perhaps someone removed it to clean it out and never replaced it, or they removed it thinking it was causing a problem.
@@TechnicalLee its kind of weird. the piston acts as weight for the fast idle cam i think. to take the weight out would not make any sense. to take the piston out you would need to knockout the expansion plug at the bottom of the bore. the plug is still there so it either a replacement or the original. maybe someone put a new plug in that would "seal" the system. i am thus on a search to find a replacement choke assembly to put on the carb. if i do, i will probably need to tke out the bottom plug, clean the bore and piston, and reinstall it and then put in a new plug (available at mikes carb in southern wshington. i am emailing carb rebuilders aqcross the country to see who has a choke. thanks. warren
Hooray for this video!! Simple, precise and easy to understand. Thank you.
That's amazing! Years ago, I talked to Jon by phone when Pony Carburetor was still in NY. He had the answer to a problem I'd had for years that nobody in my AZ chapter of Vintage Thunderbird Club including our tech advisor knew anything about. After running at highway speed, my carb would flood itself--fuel gushing down the primary venturies when I came to a stop, eventually stalling the engine. He explained that in the manufacturing, Ford left out a machining step on some of these carbs at the factory. The Venturi assemblies are supposed to have some tiny anti-siphon air bleed vent holes. The manual for my '66 Thunderbird clearly shows the vent holes and identifies them. However, looking at mine, they're not there. I got one of the units where they missed machining them. My carb was siphoning fuel after a high vacuum running condition because of it. He said when they re-engineer one of these carbs, they add those vent holes to eliminate the problem. I asked him how he can drill a hole that small in diameter, there are no drill bits that small and he laughed, said it's a trade secret. If I could add photos here, I have one of my venturi cluster and the illustration in the manual. Nobody else I've talked to is aware of this issue.
So *that's* what those little tiny holes are for! I was wondering about that when I put my carb back together after cleaning everything... They didn't look like they were actually connected to much of anything...
Thank you so much! This video was so clearly shot and your instruction & examples so easy to follow along!
Just got my car from no idle to running in gear, thanks again.
Just finished rebuilding the carb on my '68 Galaxie 390 -- this video will come in *very* handy when I get ready to install the carb and get it running. Thanks so much!
thanks for the info. and being a nice person and trying to help I will try passing this on to some one else who may also need help thanks again and have a great day lynn
Another awesome tutorial!!! Thank you .
Great video explanation of the settings of my carburator, thanks a lot Lee
ok i got your reply and was able to do it. thanks for your very helpful video. excellent.!
We used to replace those carbs with a Holley because the secondarys would hang wide open when you pushed it to the floor. We were afraid to kick it wide open. You would have to take it out of gear and turn off the engine to get it to stop. I realized as I got older that it was because the white plastic rod that helps push the secondaries closed would break off. I only owned one out of many that still had that rod intact. I thought that the white piece of remaining plastic was there to keep the screw behind it tight. I think that every rebuild kit for these carbs should come with a new nylon secondary shut off pin. I have bought a lot of different rebuild kits for these carbs and none of them had one. I put a screw with just enough threads to hold it in, in that position now. You should address this in one of your videos.
Great video. I rebuilt my C5AF 4100. Where did you get the ported vacuum fitting and your fuel filter. I'm having a tough time finding these.
were did you get that carb , I been looking for one
Probably the best video regarding the 4100. Here's my issue. Car starts and runs fine. When pulling up to a stop sign I can feel the engine running to fast. Put it in neutral tap the gas the engine returns to it regular idle speed. Start driving again, next stop sign, same issue. You would think the choke plate had closed but it isn't it's wide open. I've checked each time when the idle is to fast. I think perhaps the fast idle linkage is hanging up or it way out of adjustment. With all the adjustment required where would you start? Or is it another part of the carb that could be causing this? Thanks
Hard to say, could be the throttle is sticking somewhere other than the carb. Best to just go through all the adjustments in the video start to finish.
I like this video! Had my 4100 "rebuilt", restored a couple years ago by a guy who used to work for Pony Carburetor. It looked great but has a couple problems. My fast idle cam isn't moving into position when the choke is cold (closed) but my worst problem is that on a cold start, fuel floods out of both carb vents on top of the bowls. Lots of fuel! I've checked the float levels and they're right where they should be. If those needle/seat valves are closed, how is fuel getting past them to overfill the bowls?
The one in the video is a Pony rebuild the late Jon worked on FYI. :) If you have overflow problems, I would check fuel pressure first to make sure it's not excessive, especially if you have an electric pump or regulator in the system. I think 6.5 psi is the max spec. Otherwise fuel should not overflow if the floats and needle valves are working. Make sure the floats are bent correctly so they are level when the fuel level is at the correct height. Needle valves can also stick open/closed if they varnish or the seats get old and sticky. May need to clean and replace. Fast idle cam should be completely loose and free moving with the choke cap off and the throttle opened, perhaps it is sticking or something got bent. It should fall into place by gravity when the throttle is opened.
Thanks for the info. Before I saw your reply, I checked my choke linkage and adjusted the fast idle cam adjustment screw on top. It was way out of adjustment and not making contact with the stop. Using your adjustment video info, I set it up accordingly and it worked great. My fuel pump is OE type, not electric and I replaced it while the carb was off the car being "restored". It's the style with the filter canister integral with the pump. Could that pump output pressure excessive enough to overcome closed needle and seat valves?
I wouldn't make assumptions and would just test the fuel pressure with a gauge. Perhaps the mechanical pump isn't performing to specs. High pressure will push open the needle valves. They could also not be sealing.
Great vid, solved a few of my Q's. Where do you find the clearance specs? I have a 4300. thx!
Some book I had. You can probably find the specs online or buy a book.
yes sir wrote you awhile back and you helped me out with info. on how to make a check ball weight for my 4100 carb got it fixed and the weight works fine but started having another problem to make a long story short the car wont run with the choke all the way open I though vacuum leak but could not find one but instead I did find a crack in the carb right under the mounting bolt of the choke toward the front of the carb I don't know if I cracked it when I tighten it down or it was already there it looks like it is next to a casting seam is there any way to fix this or is it junk the only thing I can think of would be something like jb weld do you think this will work it is really a small crack thank you for your help
Try spraying carb cleaner on the crack while it's idling to verify that it's a vacuum leak. If it is a leak and you've tried a new gasket, then you can try hi-temp RTV sealant on it. If engine is fully warm, you're sure there are no vacuum leaks, and it doesn't run without choke being closed some, then you should check the timing and the idle mixture adjustments. But vacuum leaks are the most common cause (check all lines and upper/lower intake manifold gaskets too). Crack doesn't sound good, might get bigger with thermal cycling. Might have to junk it if it's leaking internally.
thanks for the info. I will double check everything for vacuum leaks all the hoses has been replaced and could not find any leaks around the intake or carb mounting flange the crack I mention is right in the center of the carb body side right below the top mounting screw for the choke it is a quarter of an inch cross but the crack run out 3 different directions almost like it has been punched with something it is also discolored around the crack a faint gold color that is what made me notice it like some one has tried to repair this crack before I happened to shine a blue light on it and it high lighted the area then I could see it real good thanks again for all your help
can you please explain proper procedure adjustments for an autolite 1100, choke adjustments.
Yes please!
i found replacement choke housing in my junk pile on an old 2100 ford carb. th piston was frozen but i got it moving with some pb blaster and heat. it still is binding a bit at the top of its travel. i know i an knock out the expansion plug at the bottom of the bore and clean oout the lower part. the piston is held in place by a rivet to the choke lever. i think. can i easily get the piston out to really clean out the bore well so there is no binding?. they make replacement explosion pugs for the bottom
the piston is attached directly to an arm/lever that that is held to the choke plate rod by a nut. If you remove the nut, the arm assemply and piston can be pulled out. I had to do this myself to clean the piston and its cylinder. The arm has flats on it, so you cannot put it back together wrong. Before you put it back together, notice that the top face of the piston has a channel,groove across it. Notice also that the cylinder wall has a hole in it. The adjustment requires you to make a hook out of a paper clip, and put the hook end into a hole in the cylinder wall NEAR the top. Now, when the piston tries to travel upward, it will strike that hook in the wall of the cylinder and be prevented from coming any further up. The additional complication is that the paperclip hook needs to not only be hooked into the cylinder wall.... but it needs to be hit by the groove across the top of the piston, and NOT by the top face of the piston.
My autolite 4100 does not have the adjustment at the top of the air horn; the one you mention at the 3:25 mark. What should I do? Ford made many versions of this carb. According to my Ford shop manual - mine is supposed to have a magnet that help close the choke on that air horn and I don't have that either. It is the original carb to the car.
The magnet chokes are somewhat rare, since there isn't an adjustment I think you just skip that one. If the magnet is missing you might have trouble starting the engine if the choke doesn't close fully. Might need to compensate more with the choke cap adjustment so it closes fully before cold start.
@@TechnicalLee Thanks! I ran into another 4100 in my buddies T-bird and inside his choke he did not have the piston pulldown for the choke pull off. His was a spring with an adjustment screw to adjust pull off. Are those better? I have one in my parts carb; seems easier than the paper clip method.
My choke plate just flops open no matter how i adjust it. it doesnt have that nice springy tension. I checked the thermostat and its in the groove
Turn the choke cap then until you get spring tension.
Was following you until you said something about adjusting the bottomed Screw to the "V" but theres no way possible it can touche the V because you have it sitting on that bottom bolt, and the screw is no where near the V.
I assume you are talking about #3 fast idle speed adjustment. First warm up the engine and shut it off. Manually open the throttle a little bit and then move the fast idle cam so that screw is aligned with the V, and then let go of throttle so the screw is touching the cam and sitting on top of the V with hands off. It's hard to see sometimes so you have to get your head under there with a flashlight. Then start the engine and adjust the screw while watching the tachometer until the warm idle speed meets spec. In the video I had the throttle blocked open from the previous adjustment, which is why the screw wasn't touching the cam (I was just showing the marks rather that doing the actual adjustment).
i dont understand what yo hook the paper clip to on choke pulldown. don't you just wan the piston at y the top of its travel? i have a '66 carb, same as your '65 autolite 4100
There's a groove in the side of the cylinder bore, you set the end of the bent paperclip in the groove and pull up until it hits the top edge of the groove. Then move the linkage so the piston is pressing up on the paper clip holding it in place. The idea is to hold the piston in a specific position to make the adjustment. Just bend the paper clip and feel around in there if you can't see it. Piston at top of travel will cause an incorrect setting.
What would cause the choke plate to stay open ? My 61 t bird the choke wont close it springs open
Probably the choke cap adjustment is off. That's #4 in the video. I would go through and adjust everything like I did, and pay attention to how I recommend you set the choke cap around 8:30. If the other adjustments are off that can happen as well (check all the adjustments if you want it to work right).
@@TechnicalLee Thankyou that was exatly the issue now the car idles. But the choke plate doesn't close all the way still , maybe open 1/8"in still and can't seem to get anymore adjustment out of the linkage
@@dustinshenefelt9887 I think if the fast idle cam screw is in too far it might prevent it from closing all the way. Go through and do adjustment #1 and #2 in the video so fast idle cam isn't being maxed out. Also make sure throttle is only open like 1/2 during adjustment otherwise choke unloader will be pushing it open.
@@TechnicalLee Thanks so much for your help everything seems to be in order and the motor is running better than ever now
yes wanting to ask a question took my 4100 apart to rebuild and discovered that my check ball weight was missing that's in the mane fuel delivery I have heard every one say I can make one but they can not tell me the length of the check ball weight do you know the size of this check ball weight or would you have one you would be willing to sale thanks for any info. lynn
0.89" of 1/8" diameter brass rod. www.carburetor-blog.com/autolite-4100-carburetor/
@@TechnicalLee i opened the choke housing on my 66 c6sfc autolite and there is a lever but there is no brass piston connected to the lever. did they make carbs without the piston if so did the choke work properly. there was a swap meet purchase. dont think someone would remove the piston..
@@vermbird8393 I'm not an expert on all the variations, but I would guess that the piston needs to be there. Without it the vacuum choke unloader function won't work and the choke may stay too far closed after engine start, possibly causing a start and stall condition. Perhaps someone removed it to clean it out and never replaced it, or they removed it thinking it was causing a problem.
@@TechnicalLee its kind of weird. the piston acts as weight for the fast idle cam i think. to take the weight out would not make any sense. to take the piston out you would need to knockout the expansion plug at the bottom of the bore. the plug is still there so it either a replacement or the original. maybe someone put a new plug in that would "seal" the system. i am thus on a search to find a replacement choke assembly to put on the carb. if i do, i will probably need to tke out the bottom plug, clean the bore and piston, and reinstall it and then put in a new plug (available at mikes carb in southern wshington. i am emailing carb rebuilders aqcross the country to see who has a choke. thanks. warren
This looks nothing like my 4100 on my '65 Park Lane, I'm confuzzled now, lol
Maybe you don't have a 4100. This 4100 looks exactly like all the 4100's I've seen, and I mainly play with 65 and 66 Thunderbirds.