cold start/choke issues? What to look at?

[Rusty_S85]

The hot air does *not* hook into actual exhaust. There is a hollow tube-like compartment built on the side of the passenger stock exhaust manifold. It serves as a *chamber* to collect hot air generated off of the exhaust manifold. The choke tubes pressed into the top and bottom of the chamber (hot air rises) to circulate the air from the filtered side of the carburetor (when the air cleaner is in place) to the choke cap. Inside of this chamber would have been a mesh filter that would also serve to hold the heat in the chamber. It would look like this:

https://www.npdlink.com/product/fitting-and-screen-choke-stove-pipe/143995

The reason for the fresh air tube is so the choke cap will only see clean, filtered air. The air you pull into the choke assembly will ultimately make it's way into the engine. So ideally you would want to use filtered air. Some of the older carburetors like my Autolite 4100 used a piston in the choke cap to operate the choke. If it pulls dirty air, it can possibly jam up the piston and render the choke useless.

(If you do not run the fresh air tube, make sure to cap off the connection under the carburetor air horn so that it does not pull unfiltered air into the carburetor.)

That is why I tapped the second hole in the other end of the [chamber] dome and ran another tube up to the carburetor air horn connection. I purchased the filter above and pushed it into a slighter larger copper tube, and placed that assembly under the [chamber] dome. Then I pushed the choke tubes into either side of the [chamber] dome so it mimicked the factory setup as close as possible. It has been like that for about ten years now, and I haven't had any problems.

Inside that tube in the manifold there is actually a heavy gauge steel wool like rod that pops in to help increase the heating area for the air that flows through.

You can actually buy these steel wool like rods still NOS off ebay along with the bottom cap that hammers in to seal it up. I actually picked up a NOS box of both the rods and the caps. The box for the rods came 3 to a box, the caps are just 1 to a box.

[LARIAT 85]

Thats a possibility for mine. But the 2V 2150 carb on my '82 is the same one on my '78 351W, they are both 351cfm 2150s. No stumble on my 351W but stumble on my 302. Cant be too much fuel from the accelerator pump as when I increased the squirt it made a positive difference in reducing some of the stumble.

There is your problem.

You have a stumble on your 302 because the carburetor is too big. The correct carburetor for your 302 would have been a 287cfm (1.08) Motorcraft 2150.

 

[rcarlisle]

Yeah, I know what "proper" is supposed to be. But this one ain't proper for sure.

Thanks for all the information you included. But I can tell you in all honesty, I'm not that inspired to fix this thing. It does start and run. It will start on one pump, just usually sputters out. Probably better than 90% of the trucks on FB?. You guys here are that last 10%. The upper echelon.

If the choke would close up some, it would probably stay running. If I can get the choke plate working somewhat, I'm sure I'll be happier. If not, it's like an old car or motorcycle - just have to let it warm a bit more. Usually I just keep my foot on pedal to give it a fast idle while I get me adjusted and seat belt on, etc.

As for your off idle stumble, when I worked for the state motorcycle program (stay with me), the majority of our Honda 250 cc Nighthawks and Rebels had a stumble off idle. On some investigation, turned out the ones that didn't stumble had a bigger idle jet. My solution for the ones that stumbled was to put a #4 brass washer under the top of the needle to shim the plunger needle up a bit. Made 300 bikes run better in NC. There is probably a similar solution for the truck carb - figure out how to richen it up between idle and that acc pump squirt. The Hondas had an honest-to-God accelerator pump on them.

If I could get to the carb to study it better, this choke thing would be a lot easier. When I get photos tonight, I will be able to study it all a llittle closer. But there are still a lot of moving parts behind the choke pot thing. Thought about buying a new carb, but till I figure out if all the stuff is there, it might not fix it.

Thats a possibility for mine. But the 2V 2150 carb on my '82 is the same one on my '78 351W, they are both 351cfm 2150s. No stumble on my 351W but stumble on my 302. Cant be too much fuel from the accelerator pump as when I increased the squirt it made a positive difference in reducing some of the stumble.

But I am getting away from all that, aftermarket fuel injection is where I am going myself. Everything works on my carb but the stumble is what got me and the more I think about it I rather have aftermarket fuel injection with way more adjustability that will actually change with elevation and ambient air temperature.

I have seen all these videos with Snipers and got a little excited. Til I saw the price. This truck is for fun. Never be perfect or anykind of show truck or daily driver, even though I like it pretty good. I am a bit envious of you guys that have patience and funding for stuff like that. While we're not poor, I can't justify EFI costs to me or the wife.

 

[rcarlisle]

The hot air does *not* hook into actual exhaust. There is a hollow tube-like compartment built on the side of the passenger stock exhaust manifold. It serves as a *chamber* to collect hot air generated off of the exhaust manifold. The choke tubes pressed into the top and bottom of the chamber (hot air rises) to circulate the air from the filtered side of the carburetor (when the air cleaner is in place) to the choke cap. Inside of this chamber would have been a mesh filter that would also serve to hold the heat in the chamber. It would look like this:

https://www.npdlink.com/product/fitting-and-screen-choke-stove-pipe/143995

The reason for the fresh air tube is so the choke cap will only see clean, filtered air. The air you pull into the choke assembly will ultimately make it's way into the engine. So ideally you would want to use filtered air. Some of the older carburetors like my Autolite 4100 used a piston in the choke cap to operate the choke. If it pulls dirty air, it can possibly jam up the piston and render the choke useless.

(If you do not run the fresh air tube, make sure to cap off the connection under the carburetor air horn so that it does not pull unfiltered air into the carburetor.)

That is why I tapped the second hole in the other end of the [chamber] dome and ran another tube up to the carburetor air horn connection. I purchased the filter above and pushed it into a slighter larger copper tube, and placed that assembly under the [chamber] dome. Then I pushed the choke tubes into either side of the [chamber] dome so it mimicked the factory setup as close as possible. It has been like that for about ten years now, and I haven't had any problems.

Inside that tube in the manifold there is actually a heavy gauge steel wool like rod that pops in to help increase the heating area for the air that flows through.

You can actually buy these steel wool like rods still NOS off ebay along with the bottom cap that hammers in to seal it up. I actually picked up a NOS box of both the rods and the caps. The box for the rods came 3 to a box, the caps are just 1 to a box.

I'll go a looking for the filter material. Thanks. Probably be a couple weeks before I delve deep into this.

[Rusty_S85]

Thats a possibility for mine. But the 2V 2150 carb on my '82 is the same one on my '78 351W, they are both 351cfm 2150s. No stumble on my 351W but stumble on my 302. Cant be too much fuel from the accelerator pump as when I increased the squirt it made a positive difference in reducing some of the stumble.

There is your problem.

You have a stumble on your 302 because the carburetor is too big. The correct carburetor for your 302 would have been a 287cfm (1.08) Motorcraft 2150.

Maybe but its original to the truck and if the stumble was because the carb is too big then wouldnt increasing the accelerator pump shot make the stumble worse? When I increased the shot by going to the outter most hole the stumble improved and wasnt as bad indicating not enough fuel was squirting for that initial tip in.

[Rusty_S85]

Yeah, I know what "proper" is supposed to be. But this one ain't proper for sure.

Thanks for all the information you included. But I can tell you in all honesty, I'm not that inspired to fix this thing. It does start and run. It will start on one pump, just usually sputters out. Probably better than 90% of the trucks on FB?. You guys here are that last 10%. The upper echelon.

If the choke would close up some, it would probably stay running. If I can get the choke plate working somewhat, I'm sure I'll be happier. If not, it's like an old car or motorcycle - just have to let it warm a bit more. Usually I just keep my foot on pedal to give it a fast idle while I get me adjusted and seat belt on, etc.

As for your off idle stumble, when I worked for the state motorcycle program (stay with me), the majority of our Honda 250 cc Nighthawks and Rebels had a stumble off idle. On some investigation, turned out the ones that didn't stumble had a bigger idle jet. My solution for the ones that stumbled was to put a #4 brass washer under the top of the needle to shim the plunger needle up a bit. Made 300 bikes run better in NC. There is probably a similar solution for the truck carb - figure out how to richen it up between idle and that acc pump squirt. The Hondas had an honest-to-God accelerator pump on them.

If I could get to the carb to study it better, this choke thing would be a lot easier. When I get photos tonight, I will be able to study it all a llittle closer. But there are still a lot of moving parts behind the choke pot thing. Thought about buying a new carb, but till I figure out if all the stuff is there, it might not fix it.

Thats a possibility for mine. But the 2V 2150 carb on my '82 is the same one on my '78 351W, they are both 351cfm 2150s. No stumble on my 351W but stumble on my 302. Cant be too much fuel from the accelerator pump as when I increased the squirt it made a positive difference in reducing some of the stumble.

But I am getting away from all that, aftermarket fuel injection is where I am going myself. Everything works on my carb but the stumble is what got me and the more I think about it I rather have aftermarket fuel injection with way more adjustability that will actually change with elevation and ambient air temperature.

I have seen all these videos with Snipers and got a little excited. Til I saw the price. This truck is for fun. Never be perfect or anykind of show truck or daily driver, even though I like it pretty good. I am a bit envious of you guys that have patience and funding for stuff like that. While we're not poor, I can't justify EFI costs to me or the wife.

This engine build is 3 years in the making. Its the only way I was able to source the parts I have including the sniper. I just know I am getting anxious now cause I am close to having my truck back on the road after sitting for 3 years.

Only reason I went with the sniper on mine is for precision. If I wanted to I could go up into the mountains and have no problem as the sniper would adjust for change in elevation. Carb wont do that youd have to change the jets out to compensate for that. Like wise I dont have a AC step up solenoid on the throttle and being mine is dealer installed it wouldnt work for me as the solenoid would cut off when the clutch cycles then when the AC kicks back in the truck would stall out as the ford step up solenoids are not strong enough to open the throttle you have to touch the throttle to allow it to extend when powered. With the sniper it uses the IAC to change the idle speed if you have it setup for that.

[LARIAT 85]

Maybe but its original to the truck and if the stumble was because the carb is too big then wouldnt increasing the accelerator pump shot make the stumble worse? When I increased the shot by going to the outter most hole the stumble improved and wasnt as bad indicating not enough fuel was squirting for that initial tip in.

It might be original to your truck when you bought it, but that doesn't change the fact that it isn't the original carburetor Ford designed for it. I promise you that your truck didn't have a "stumble" when it was new.

There was much more engineering going on with these Ford carburetors than you might think. Even though your two Motorcraft 2150 2V carburetors may look exactly the same from the outside, almost everything inside of them are going to be different. (That is why they had carburetor tags on them.) The venturi size, booster assemblies, jet sizes, and even basic adjustments are different from vehicle to vehicle. They are different to precisely accommodate the type of vehicle they are used with. Ford took into account vehicle type, vehicle size, vehicle weight, emissions, engine size, engine family, and even transmission type when they engineered their carburetors for each application. You can't just adjust the idle mixture screws (or accelerator pump shot) and think a Motorcraft 2150 that was designed to run on a 1982 Ford LTD with a 351 engine and an AOD transmission is going to run as good on a 1982 Ford F150 with a 302 engine and a C6 automatic.

Only reason I went with the sniper on mine is for precision. If I wanted to I could go up into the mountains and have no problem as the sniper would adjust for change in elevation. Carb wont do that youd have to change the jets out to compensate for that.

I think that is misleading. While it is true that a carburetor cannot self-adjust for change in elevation, it's not like a carburetor cannot handle it at all. Vehicles with carburetors have been going up and down mountains for many more years than vehicles with fuel injection systems have, and no one was on the side of the road changing out jets. Yes, an electronic fuel injection system is going to be able to self-adjust and therefore be more "precise" than a carburetor when dealing with changes in elevation. But at what cost?

The only real reason to replace a carburetor with EFI is for the ability to self-tune. In exchange, you have to spend a lot of money to get a lot of wires, a lot of sensors, and a computer to make that happen. And you better learn to work on your truck yourself, because no one else is going to want to work on a vehicle with an aftermarket fuel injection system on it. The truth is, if you replace your carburetor with an EFI system and you get a big increase in performance or fuel economy, then something was not right with your carburetor.

And just to be clear, I would never replace a perfectly good EFI system with a carburetor, either. BOTH systems work great when they are dialed in and functioning correctly. I just don't think you are being very fair to carburetors.

Like wise I dont have a AC step up solenoid on the throttle and being mine is dealer installed it wouldnt work for me as the solenoid would cut off when the clutch cycles then when the AC kicks back in the truck would stall out as the ford step up solenoids are not strong enough to open the throttle you have to touch the throttle to allow it to extend when powered. With the sniper it uses the IAC to change the idle speed if you have it setup for that.

Again, I think that is misleading. I have a solepot (combination idle solenoid and dashpot) on my Lucille and it doesn't have that problem. If your truck completely stalls when the A/C clutch engages and the solepot is retracted, then that means your curb idle speed is simply set too low. Yes, the idle speed will drop a bit until the solepot extends and pushes the throttle up, but it should not stall. And even then this situation would only happen if you are sitting there at idle and do nothing about it. If you are actually driving your truck, it wouldn't be a problem at all because the throttle would be constantly open, allowing the solepot to extend whenever it is energized.

[Rusty_S85]

Maybe but its original to the truck and if the stumble was because the carb is too big then wouldnt increasing the accelerator pump shot make the stumble worse? When I increased the shot by going to the outter most hole the stumble improved and wasnt as bad indicating not enough fuel was squirting for that initial tip in.

It might be original to your truck when you bought it, but that doesn't change the fact that it isn't the original carburetor Ford designed for it. I promise you that your truck didn't have a "stumble" when it was new.

There was much more engineering going on with these Ford carburetors than you might think. Even though your two Motorcraft 2150 2V carburetors may look exactly the same from the outside, almost everything inside of them are going to be different. (That is why they had carburetor tags on them.) The venturi size, booster assemblies, jet sizes, and even basic adjustments are different from vehicle to vehicle. They are different to precisely accommodate the type of vehicle they are used with. Ford took into account vehicle type, vehicle size, vehicle weight, emissions, engine size, engine family, and even transmission type when they engineered their carburetors for each application. You can't just adjust the idle mixture screws (or accelerator pump shot) and think a Motorcraft 2150 that was designed to run on a 1982 Ford LTD with a 351 engine and an AOD transmission is going to run as good on a 1982 Ford F150 with a 302 engine and a C6 automatic.

Only reason I went with the sniper on mine is for precision. If I wanted to I could go up into the mountains and have no problem as the sniper would adjust for change in elevation. Carb wont do that youd have to change the jets out to compensate for that.

I think that is misleading. While it is true that a carburetor cannot adjust for change in elevation, it's not like a carburetor cannot handle it at all. Vehicles with carburetors have been going up and down mountains for many more years than vehicles with fuel injection systems have, and no one was on the side of the road changing out jets. Yes, an electronic fuel injection system is going to be able to self-tune and therefore be more "precise" than a carburetor when dealing with changes in elevation. But at what cost?

The only real reason to replace a carburetor with EFI is for the ability to self-tune. In exchange, you have to spend a lot of money to get a lot of wires, a lot of sensors, and a computer to make that happen. And you better learn to work on your truck yourself, because no one else is going to want to work on a vehicle with an aftermarket fuel injection system on it. The truth is, if you replace your carburetor with an EFI system and you get a big increase in performance or fuel economy, then something was not right with your carburetor.

And just to be clear, I would never replace a perfectly good EFI system with a carburetor, either. BOTH systems work great when they are dialed in and functioning correctly. I just don't think you are being very fair to carburetors.

Like wise I dont have a AC step up solenoid on the throttle and being mine is dealer installed it wouldnt work for me as the solenoid would cut off when the clutch cycles then when the AC kicks back in the truck would stall out as the ford step up solenoids are not strong enough to open the throttle you have to touch the throttle to allow it to extend when powered. With the sniper it uses the IAC to change the idle speed if you have it setup for that.

Again, I think that is misleading. I have a solepot (combination idle solenoid and dashpot) on my Lucille and it doesn't have that problem. If your truck completely stalls when the A/C clutch engages and the solepot is retracted, then that means your curb idle speed is simply set too low. Yes, the idle speed will drop a bit until the solepot extends and pushes the throttle up, but it should not stall. And even then this situation would only happen if you are sitting there at idle and do nothing about it. If you are actually driving your truck, it wouldn't be a problem at all because the throttle would be constantly open, allowing the solepot to extend whenever it is energized.

I know all about the internal differences and those internal differences is mainly the venturi booster which is lettered for different applications. Im actually working on compiling a list for a guy on youtube for different applications. Surprising most of those numbers cross over to multiple vehicles. Now with that said the venturi booster will not cause a stumble off idle. There is only one circuit that is involved when you step down on the throttle and that is the accelerator pump. The initial hit is where my problem only arose and it was not noticeable when already moving. Could be a combination of issues such as over sized tires with OE 2.75:1 axle ratio and a 120hp 302. But the carb being too big cause its 351 cfm would not cause this issue. In fact when I was looking at 4V upgrades many have told me to go with 600 cfm as that is what Ford ran on the 302s in the past and I was looking more at 500 cfm. Still any stumble you have when you step on the throttle is in the accelerator pump circuit no where else, its carb diagnosis 101.

As far as the jet changes goes, it should be done when you change elevation. you may be fine with in a certain range but once you exceed that the thinner air the higher you go seriously changes your air/fuel mixture and unless you want to let it ride and go super rich then you dont have to change it. But even when carbs were common place people still complained of drastic elevation changes resulting in drastic changes in engine performance.

Like I said I wont be making those kind of elevation changes. Its an added benefit for me, the aftermarket EFI is to improve on the overall package. With the ethanol blended fuels we have today you run into more issues with carbs as the fuel in the bowl is directly open to the atmosphere and after a few days in a humid region that fuel will have separated with ethanol/water on the bottom and what remains of the fuel that hasnt evaporated floating up on top. It is a problem I know all too well with my vehicles and its worse with ones where the fuel is exposed directly to the atmosphere. In those instances youd be lucky if the fuel lasts more than 3 weeks before it fully separates.

As far as people working on them, there wouldnt be a problem, there are numerous shops that are authorized dealers and installers that you can take one to if you have a problem. But typically you wont have a problem as everything is self contained. If there is a problem you just send the whole unit back to Holley for checking and repairs. There really isnt much you can do with this system on your own as parts such as IAC, MAP, Injectors are holley specific and they have no listing of replacements for people that would change them out themselves. Only thing you can really get is the o2 sensor with a wealth of different part numbers for replacements from a short lead to a long lead. Really the biggest problem you will have with one of these units is RFI if you dont follow the instructions on installation. The next biggest issue is the injectors coming unplugged due to the tiny connector Holley uses to fit the injector assembly with in a carb look alike housing. Many have fixed this issue with a tiny ziptie.

There is also a large number of people online on the offical owners group on fb that will walk you through diagnosis as well as repairs or if it needs to be sent back to holley.

On the notion of getting better fuel economy with efi over a carb that is a given, its not necessarily your carb is setup bad hence why you got bad fuel economy. Power also plays a part in fuel economy as well, more throttle you have to apply to get moving means more fuel you are burning. In my case I will see a huge increase in fuel economy with my new engine build with EFI over my stock smog 302 with carb because the engine was under powered for my truck how its built. With the EFI with proper tuning of the fuel map with the new engine build I should see at least 18 highway. But fuel economy is not the sole reason why I decided to go fuel injection it is a benefit. There is just so many reasons to go with aftermarket EFI with todays fuels over struggling with carbs and the new issues todays fuels bring about.

The idle specs for my truck when its listed with AC is not compatible with dealer AC. the York compressors have a way larger drop in rpm than the rotary style compressor ford was using on the factory setup. The spec is 575 rpm in gear with the AC off, with the AC on the idle speed is supposed to be 650 rpm in gear. So if I set my truck properly at the proper rpm to attain 575 rpm in gear with AC off and switch the AC on it will stall out. 575 rpm is way too low of a rpm with AC compressor that has a high load. Long as it doesnt cycle off and back on you would be fine with the step up solenoid, I dont have that problem on my 78 Mercury but that York compressor doesnt cycle as its an expansion valve system. My truck how ever cycles as there is no blend door to introduce ambient air or hot air to change the output of the vent. To change the temperature out of the vent you have a rheostat that will change what temperature the clutch cycles off at. That poses a big risk when you have your engine idling at 575 with the AC off. I currently dont have a step up solenoid and the AC is set up to idle at 575 with the AC on and with the AC off its around 650/700 rpm.

In the end this poses a big problem as if I turn the temp down just a little the compressor will cycle while I am sitting at a redlight even and surely you can see where I am going with this. If you are at a redlight idling at 650 rpm with the AC on and the solenoid extended only for the compressor to cycle off the solenoid collapses idles back down to 575 then the compressor kicks back on and bam your compressor brings your idle speed down to 400 and stall. The solenoid is not strong enough to push your throttle open, Ive never seen a factory one strong enough to push the throttle open. Even installing NOS ones doesnt help as they are weak solenoids and rely on you touching the throttle to allow the solenoid to move out. Like you said wouldnt be a problem on the road driving down the highway but in city driving with dealer AC that has a power hungry compressor with a cycling system to determine how cold the air coming out of the vents are, you would have some serious problems with the OE setup. Maybe it will work fine with the factory style compressor but it wont work properly with a york compressor. I dont believe Ford ever had a cycling switch on York equipped AC systems.

[LARIAT 85]

I know all about the internal differences and those internal differences is mainly the venturi booster which is lettered for different applications. Im actually working on compiling a list for a guy on youtube for different applications. Surprising most of those numbers cross over to multiple vehicles. Now with that said the venturi booster will not cause a stumble off idle. There is only one circuit that is involved when you step down on the throttle and that is the accelerator pump. The initial hit is where my problem only arose and it was not noticeable when already moving. Could be a combination of issues such as over sized tires with OE 2.75:1 axle ratio and a 120hp 302. But the carb being too big cause its 351 cfm would not cause this issue. In fact when I was looking at 4V upgrades many have told me to go with 600 cfm as that is what Ford ran on the 302s in the past and I was looking more at 500 cfm. Still any stumble you have when you step on the throttle is in the accelerator pump circuit no where else, its carb diagnosis 101.

Have you tried rebuilding the carburetor? A complete rebuild kit is only about $35. If that doesn't work, I bet the correct carburetor would fix your problem.

As far as the jet changes goes, it should be done when you change elevation. you may be fine with in a certain range but once you exceed that the thinner air the higher you go seriously changes your air/fuel mixture and unless you want to let it ride and go super rich then you dont have to change it. But even when carbs were common place people still complained of drastic elevation changes resulting in drastic changes in engine performance.

For optimum performance, a jet change would be needed to compensate for drastic elevation changes to match EFI. That would require a set of $10 jets, a large-blade screwdriver, and about 15 minutes of your time (with an Autolute 2100/4100 or Motorcraft 2150). And then you are back in the game. Or, you could spend about $2000 on a complete aftermarket fuel injection system so you don't have to do that and enjoy the satisfaction of knowing you have a more precise air/fuel mixture than an outdated carburetor.

With the ethanol blended fuels we have today you run into more issues with carbs as the fuel in the bowl is directly open to the atmosphere and after a few days in a humid region that fuel will have separated with ethanol/water on the bottom and what remains of the fuel that hasnt evaporated floating up on top. It is a problem I know all too well with my vehicles and its worse with ones where the fuel is exposed directly to the atmosphere. In those instances youd be lucky if the fuel lasts more than 3 weeks before it fully separates.

I live in the South East and I don't experience that problem at all. But I make a point to drive my Lucille at least once a week for 30 minutes to keep everything circulating and in good running shape. It is not good for any vehicle to sit for a long period of time.

As far as people working on them, there wouldnt be a problem, there are numerous shops that are authorized dealers and installers that you can take one to if you have a problem. But typically you wont have a problem as everything is self contained. If there is a problem you just send the whole unit back to Holley for checking and repairs. There really isnt much you can do with this system on your own as parts such as IAC, MAP, Injectors are holley specific and they have no listing of replacements for people that would change them out themselves.

I think you said it all right there. If you are stranded in the middle of nowhere, what are you going to do to get your truck back on the road? Is it worth it just to beat that old carburetor in a drag race up in the mountains because the owner neglected to change out his jets to compensate for a drastic elevation change?

In the end this poses a big problem as if I turn the temp down just a little the compressor will cycle while I am sitting at a redlight even and surely you can see where I am going with this. If you are at a redlight idling at 650 rpm with the AC on and the solenoid extended only for the compressor to cycle off the solenoid collapses idles back down to 575 then the compressor kicks back on and bam your compressor brings your idle speed down to 400 and stall. The solenoid is not strong enough to push your throttle open, Ive never seen a factory one strong enough to push the throttle open. Even installing NOS ones doesnt help as they are weak solenoids and rely on you touching the throttle to allow the solenoid to move out. Like you said wouldnt be a problem on the road driving down the highway but in city driving with dealer AC that has a power hungry compressor with a cycling system to determine how cold the air coming out of the vents are, you would have some serious problems with the OE setup. Maybe it will work fine with the factory style compressor but it wont work properly with a york compressor. I dont believe Ford ever had a cycling switch on York equipped AC systems.

I adjusted mine so that the idle speed is the same whether the A/C is on or not. My normal curb idle speed is set to 625 RPM. When the A/C is engaged, the solepot will adjust the idle speed back to 625 RPM. But if I am at idle and the A/C engages without the solepot extending, my idle speed will drop to about 500 RPM. That is about as low as it can go with a stable idle.

[Rusty_S85]

Have you tried rebuilding the carburetor? A complete rebuild kit is only about $35. If that doesn't work, I bet the correct carburetor would fix your problem.

For optimum performance, a jet change would be needed to compensate for drastic elevation changes to match EFI. That would require a set of $10 jets, a large-blade screwdriver, and about 15 minutes of your time (with an Autolute 2100/4100 or Motorcraft 2150). And then you are back in the game. Or, you could spend about $2000 on a complete aftermarket fuel injection system so you don't have to do that and enjoy the satisfaction of knowing you have a more precise air/fuel mixture than an outdated carburetor.

I live in the South East and I don't experience that problem at all. But I make a point to drive my Lucille at least once a week for 30 minutes to keep everything circulating and in good running shape. It is not good for any vehicle to sit for a long period of time.

I think you said it all right there. If you are stranded in the middle of nowhere, what are you going to do to get your truck back on the road? Is it worth it just to beat that old carburetor in a drag race up in the mountains because the owner neglected to change out his jets to compensate for a drastic elevation change?

I adjusted mine so that the idle speed is the same whether the A/C is on or not. My normal curb idle speed is set to 625 RPM. When the A/C is engaged, the solepot will adjust the idle speed back to 625 RPM. But if I am at idle and the A/C engages without the solepot extending, my idle speed will drop to about 500 RPM. That is about as low as it can go with a stable idle.

The carb has been rebuilt 2 times since 1992 and one repair where a broken accelerator pump diaphragm was replaced.

As far as correct carb goes I believe the tag is on the carb still and it breaks down as being correct for my application. Still the problem lies in the accelerator pump circuit not in the venturi boosters which is what changed between carbs for different vehicles.

Sure you can quickly change the jets out but how do you know that the jets you are switching out to is the ones you need to switch to? or do you just carry a set of jets and do trial and error a few times to find the right jets? After all im sure you know that no two engines are alike and what one engine likes jet wise at a specific altitude doesnt mean another engine will like it.

I experience that problem its not as bad on my truck with the closed evap system but it is way more noticeable on my 56 which has a large vent straight to the atmosphere next to the gas cap behind the license plate. This allows the ethanol to absorb moisture at a extreme rate during high humidity. Then if you run Stabil 360 which is a ethanol stabilizer to stop the ethanol issues does help but its not a end all task for vehicles that dont get driven enough, in my case on my 56 even if I run the car for half an hour once a week it doesnt matter, you cant burn the 15 gallons of gas out of the tank quick enough before it becomes saturated with water. I could run less fuel but that just accelerates the issue as it takes less moisture in the fuel before it separates and settles with water/ethanol at the bottom of your tank. It is a no win situation if you dont burn the fuel out quick enough.

Problem is these snipers are not known for having so called drastic problems that will strand you. The most common issue is O2 sensor failure which if you have the handheld unit with you, you can switch off the closed loop and run off the base fuel map just like a modern car does. Many people think modern cars run off the o2 sensor but in reality they are running off the base fuel map with the o2 sensor monitoring for any minor changes it may have to make in extreme cases. Many people have had failed O2 sensors but was able to continue driving without a problem by switching off closed loop mode. The other problem is the injector harness connector but that is not as big as it seems. Ive installed numerous units and never had one come back with a failed O2 sensor nor with a injector connector coming loose.

Really these units are quite bullet proof and give no trouble that will leave you stranded. About the only thing that will leave you stranded is a fuel pump which is no different than any other vehicle out there that is fuel injected. That is about the only thing the carb has on it is the mechanical fuel pump can fail and leak but still keep driving at the risk of starting a fire or filling your engine up with fuel.

Yeah my york drops more than 125 rpm. Mine drops more around 175 rpm when the AC kicks in. Its why I have mine idled up as much as I do since I dont have the solenoid as it wasnt avaliable for dealer AC. With this new setup I will have the step up in the form of the computer changing the idle speed when the AC is on. I could let it maintain the base idle speed but I am going to program it to idle the engine up by around 100 - 150 rpm. Will play with it to see what the combination likes best. Same with idle speed will start off with 575 idle speed as OE specified but will have to see what my crane roller cam will like for an idle speed. Might prefer 750 as base idle for all I know but I feel 575 rpm would be a good starting point.

Now as far as performance/efficency goes I dont care how set up a carb you have the sniper will wake any engine up.

I installed one in a engine that was dyno tuned with a carb and the guy wanted to put a sniper on it instead. The engine you thought rev good in neutral and ran great on the street. Throw the sniper on and just hitting the throttle the engine was so much more responsive and so much quicker in reving it was like a kid in a candy store feeling. Driving the car woke it up so much more as well.

One have to remember these snipers are 800cfm with injectors capable of feeding 600hp with no problem. Many people actually undersize their carbs on air flow to maintain throttle response for street driving but with the sniper you dont have to worry about that as you are not relying on velocity of the air to pull in fuel from the fuel bowls. That is where the sniper will wake any vehicle up as it is a huge throttle body that can flow more air than your basic street carb and provide way snappier throttle response. Thats why I am concerned about my performer intake manifold selection cause im throwing a 800cfm sniper stealth which is the smallest they offer on a 306 with AFR 165 renegade heads that flow some 250-255 cfm at my cam lift on the intake side. I still feel like the intake manifold is going to be my bottle neck seeing as the Edelbrock Performer intake as cast is as far as I know only flows 205 cfm per runner out of the box but cant verify that.