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Discussion Starter · #1 ·
I daily drive my '77 LTD with a 351 Windsor with a 2-barrel carb (I think it’s the 2150; picture below of the tag on the carb).
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I've had the car around ten years now, and I’d say the carburetor is due for attention/replacement. It's functional, but it could be better.

I'm looking for recommendations on the best path forward. I'll run through what I've noticed and then what I'm trying to achieve. This will be quite lengthy, so bear with me.

Currently the car starts right up when it's cold; don't even have to press the pedal. However, the engine chugs when temperatures are below 55ish until it warms up. (If the car has been sitting for a long time; it will take a few pumps to get it started, but that doesn’t seem abnormal or unreasonable.)

The last year or so the car has started to become fairly difficult to start when the engine is warm. For years it has required a little bit of attention when starting warm (would have to hold the gas pedal in a specific position while starting), but lately it's been significantly more temperamental.

Since I bought the car, the engine almost without fail hesitates once for just a moment shortly after it is started. The time it takes for this to happen is not consistent, but generally occurs within the first minute of running. If it's idling, you can hear it and then the engine picks right back up. If you're driving, the car often stalls; not good when trying to pull out of a parking lot onto a busy street. It was minor enough that I've just dealt with it, but I'd really like it to go away.

If I give it too much gas at once, the engine hesitates and under some circumstances (usually if it's cold) will stall. I replaced the accelerator pump several years ago which seemed to help with this (the old one was damaged if I recall) for a little while and then the problem came back. I decided to change it again within the last week since the part is so cheap just to see what would happen; helped maybe a little bit but did not completely eliminate the problem. I am noticing gas leaking out of the weep hole since putting in the new one, which doesn’t seem right.

Pressing the gas right after making turns (most noticeably with right turns) when the engine isn't completely warmed up will make the car bog down and backfire and will sometimes stall the engine.

I noticed that a vacuum line was taken off this gizmo and plugged with a bolt.
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I have no idea what this thing is. It’s connected to a plate that sits between the carb and the intake manifold. Whatever it is, it’s been disconnected for at least ten years, but I decided to hook it back up and see what happened. It seemed to have zero effect on idle or ability to start at different temperatures, but when the engine was under load (i.e., when driving) the car started running really poorly. It'd be fine and then almost stall, then be fine, then almost stall. Taking off from stoplights was almost impossible. After a few miles of this, I disconnected the vacuum line and re-
plugged it and the problem went away. I’m curious what this thing is and what sort of negative side effects not using it might have.

In general, the engine idle just feels a little rougher with more noticeable engine vibration than it did when I first got the car. It's very subtle and maybe it's just my imagination, but my memories of ten years ago have the car running smoother (in the past people wouldn’t even realize the car was running if we were sitting in a parking lot with it idling). Engine mounts were recently replaced with no improvement to the mild engine vibration.

So with those current problems in mind, below are my priorities and concerns.

Priorities:
  • Responsiveness. My driveway exits onto a very busy road. Having the car hesitate or stall when exiting the driveway could easily result in an accident. I need the car to perform consistently when I hit the gas. Doesn't need to be fast, just needs to be predictable and reliable so that I can judge when it's safe to pull out and don't have to worry about stalling.
  • Reliability. This is my daily driver, not a showpiece that gets trailered around. It's never left me stranded anywhere, and I want it to stay that way. This car has less than 100,000 miles and I plan to drive it until it dies. While it is my daily driver, I drive it less than 5,000mi/year. It never sees snow, so rust is not an issue. So I'd like to think I'm looking at a couple more decades before this drivetrain bites the dust. Maybe my expectations are too high, but I'd like a carb that will last the remaining life of the car. I only put ethanol-free gas in the car, which should go a long way in preventing carb deterioration.
  • "Good" fuel economy. This car will never be fast, and it doesn't need to be. I average 12mpg around town with the AC running now. Getting a tuner carb that gets 10mpg and boosts my performance would be undesirable. I have no gripe with improved performance, but not if it comes at the expense of gas mileage. I would welcome a carb that gets better mileage if that's possible, but I don't expect that. It's a heavy car with no overdrive; it's going to use gas.
  • Lower idle speed. I think I’ve read before the stock idle speed on these cars is like 1,100 RPMs. To me, that's just too high, but the car just really doesn't idle well once in gear if you go below its current high setting. If there are options out there that can idle at a lower speed, I would love to make that change. But if it's just a requirement for these engines regardless of the carb, then it is what it is. I do use my AC, so that "sometimes" load on the engine may be another factor that just requires a higher idle when the load isn't present.
  • Price. I'd like to be able to do this for under $300, but I don't know if I can get a quality carb for that. I suspect I won't be able to get something that'll last decades and be cheap.
  • Stock(ish) appearance. I don't really care what the carb itself looks like, but I'd like to keep my original air cleaner, or at least something that looks tame. I don't want to have to switch to a cheesy chrome air cleaner with open sides or something like that. That's fine on a muscle car, but silly on a family sedan. This is a minor desire, so if there really is a fantastic and cheap carb out there that requires a silly air cleaner, I would make that sacrifice.

Reservations:
  • I'm leery of doing too much to my current carb. While a bit fussy, it is still functional and gets me from A to B. It's a safe fallback if a new carb has issues. I've rebuilt a carb or two in the past with lackluster results (read as: the rebuild offered zero improvement). Carb parts are delicate, and I'd hate to do something to mine and make things worse. I also had an LTD II a few years ago with a similar (if not identical) carb and it was a real bear to get running well enough to drive; never got it perfect. I've also been told Ford carbs of this era are incredibly finicky. Don't know if that's true, but it adds to my apprehensiveness to touch my current, mostly-working carb.
  • My understanding is that buying rebuilt carbs can be really hit or miss. I just had to replace a carb on another car that was beyond repair. The first carb I got from the parts store had a stripped fuel inlet and quickly developed float issues as well. Second one from the parts store was pretty filthy; installed it today. It’s running fine at the moment, but we’ll see how long it lasts. If there's a vendor that offers known quality rebuilds every time, I'd be fine with a rebuild. But I'm not sure such a place exists in this day and age.
  • I question electric chokes (which all aftermarket carbs seem to have). While I'm sure they are technically functional, they seem a bit stupid. My understanding is they are basically a timer and don't take into account actual engine temperature. My LTD gets driven in weather from 40°F up to 100°F. These different temperatures will definitely result in different engine warm-up times. I'd like my choke to behave accordingly instead of always behaving the same. I checked my hot air choke today and it is still functional (don’t know if it’s adjusted correctly, but it slowly opens as the engine warms up).

I spotted this carb that piqued my interest:
It's cheap, it's new and not rebuilt, and has good reviews. It looks almost identical to my current carb with a couple minor differences that don't look like they'll be a problem. One of those differences is an electric choke. It's also made in China. At $80, I question the longevity. Amazon is good about returns, so trying it out feels pretty low-risk...unless it leaves me stranded fifty miles from home.

Bearing everything I've said in mind, I'm looking for recommendations on how some of you might proceed in my situation with my requirements.
 

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Discussion Starter · #3 · (Edited)
Fuel filter was last replaced maybe eight years ago? Can't believe I didn't think to try that as a cheap "why not" test. Bought a new filter today; will put it on Tuesday most likely (forecast says snow/freezing rain tomorrow, so the car's not going anywhere then anyway).

Looking at the EGR valve again, I'm not sure I hooked it up correctly before. I have a low mileage '75 LTD that's been sitting since the '80s, so I took a look at it (with the assumption it probably wouldn't be too molested since it wasn't used for very long after being built). The EGR system on it is different, unfortunately (has two valves instead of just one), so it wasn't much help. However, on the '77, I noticed another vacuum port that was plugged while looking at it today. Below are a couple pictures of what I've found to be disconnected (items are colored simply to make them stand out). Not sure the correct way to put it back together. I'm assuming since I now have found two vacuum ports that aren't connected and only one vacuum line, there must be another vacuum line somewhere I've overlooked (or it's completely gone and there's a third vacuum port somewhere that I haven't seen).
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Presumably my carb has been set to run richer because I've only had issues with ping once. It was a year or two after I got the car. Drove a friend to Sam's Club and they let me use their card to buy some gas while we were there. Car would start to ping under acceleration at about 30 mph, and would stop if I let off the gas. Did it twice on that tank of gas. Never bought gas from Sam's Club again and never had the problem again. For about the first five years I owned the car, I ran it on 87 octane with 10% ethanol. I vaguely recall a short period where I used 89 octane because someone said that car would run better on it; it made no difference, so I stopped. The last five years I've run it on 90 octane ethanol-free gas. I see no need for the higher octane, it's just the only octane they sell of ethanol-free fuel at the gas station by my house.

I will say if it's running richer, it's not noticeable. The car doesn't blow black smoke and doesn't smell of gas. The worst it gets is spitting a bit of black soot the first time it's started every Spring. There is white exhaust smoke when it's cold outside, but that seems pretty normal; I see plenty of new cars do that as well. I assume that's just moisture buildup inside the exhaust being heated and blown out. The white smoke does not smell sweet, so it's not a sign of impending doom from a blown head gasket. The exhaust is still original with the catalytic converters (and without any leaks) if that matters.

I was also under the impression that EGR systems reduced mileage and performance slightly on older cars. Would hooking it back up actually be helpful? I have no gripe bypassing it if there's a way to "correctly" do it. Even though I usually try to keep things original, I'm all for a cleaner engine bay with fewer vacuum lines if it's practical. Looks nicer and fewer failure points.

I personally do not have issues with an electric choke if the electric connection can be made easily. It is a more accurate choke than non-electric.
Curiously, the '75 LTD mentioned above had what looked like a combination of a hot air and electric choke; no idea how that works. My '77 LTD does not have a place for an electrical connection on the choke like the '75 does. If I were to put on the Amazon carb, where should I tap into for the electric choke? My understanding is that you don't just tie into an ignition circuit, but you have to actually tie into something that only comes on when the car is actually running. The reason being that if the key is on and the car is off, the electric choke will still warm up as if the car is running, even though the engine is cold, then the choke won't work when you go to start the car.

I suspect your vehicle has other issues besides the carburetor. You have had it a long time but do not drive it much. The EGR should be addressed.
I suspect the intake system is gummed up and there may be amounts of varnish like coating on the inside of the intake and intake valves.
Even though I don't drive far, it has been driven daily for the most part when it's not winter. The low mileage was just from short commutes combined with the car being parked when the roads get salted in the winter. Would this still result in a varnish buildup if the car is used daily?

While picking up the fuel filter, I did buy a bottle of "Original" formula Marvel Mystery Oil to add to the gas at the next fill-up. Looks like the bottle will treat two tanks of gas.

You may have leaking vacuum lines. (Old rubber cracking)
A diagnostic step would be to get vacuum gauge readings on a warmed up engine.
Tested the intake vacuum pressure today as well (from the plugged EGR port in the picture above). It was sitting just under 22 psi once the engine was warm (it was just over 21 psi when the engine was cold, so basically no change if that matters). I did notice when you hit the gas, the pressure drops for a moment and then quickly goes back to about 22 psi if throttle is maintained, not sure if that's normal. Letting off the gas then has the opposite reaction, a very quick spike in vacuum that immediately levels back out at about 22 psi.
 

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Discussion Starter · #6 ·
Just saw this announced last week, tho' I suspect some inlet tube manipulation might be required, never mind being majorly more expensive than the approach outlined by Action with which I cannot argue.
Ford/Autolite/Motorcraft 2100/2150 Replacement
I can vouch for having successfully acquired a few parts from this business.
I think I was looking at that very same carb last night on Holley's website.
If Allstate Carburetor does quality work, I may just call them up and see if they have any rebuilt Motorcraft 2150 carbs available so I can stay stock.

I assume the numbers you posted for intake vacuum were in inches of mercury.
Yes, that is correct. Not PSI. Apologies for any confusion.

If correct, a 21 to 22 inches of mercury reading and a steady needle is a very healthy engine.
And the vacuum readings based on throttle operation are spot on.
Is there any reason for me to run the Marvel Mystery Oil then? I prefer not to dump anything extra into my fuel if I can avoid it.

For the vacuum lines, is there a paper sticker on the front of one of the valve covers?
If yes post a picture.
I may have an engine vacuum diagram I can post for you.
This was on the driver's side valve cover:
Brown Wood Font Pattern Signage


There was a sticker on the other valve cover as well that was covered in some grime. When I started trying to wipe it off, it was taking off the letters with the grime, so I stopped. If that other sticker is what you need; I'll try to figure out how to clean it without destroying it after the freezing rain stops.

EGR will not reduce fuel economy. If anything, it improves fuel economy as the mixture can be slightly leaner because the fuel in the exhaust is being burned.
It is possible performance is less. Only because the unburned fuel in the exhaust is not that good of quality.
Good to know. Fuel economy is more important to me than performance. (Though obviously I'm not hugely concerned about either given the vehicle I have chosen.)
 

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Discussion Starter · #10 ·
There appears to be no salvaging that tag. I even tried just gently dabbing the grime off and it was taking off the letters, too. I took a few pictures as I went. I'll include them below and maybe you can salvage the info you need, but probably not.
Automotive tire Wood Grey Rectangle Road surface
Automotive tire Road surface Asphalt Wood Tints and shades
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Rectangle Grey Wood Road surface Asphalt
Rectangle Wood Grey Font Tints and shades

From what I can tell, it looks like the top-left is W I with the code HG390CB after that. The punchout section on the bottom-left appears to be E10. The top-right is 326. And the column about 80% of the way across is a C on top, maybe a B or a G in the middle, and then a 3 on the bottom. The other sections are just not visible at all to me.

My car does have a plastic charcoal canister on the passenger wheel well instead of one of the metal "coffee can" ones if that's an indicator of the configuration it might use. I just noticed it also has a little connection with a cap on it, so I imagine that needs to be hooked back up as well, and as of this moment means I've now found the correct number holes to hook everything up as long as I know which goes where. There's also a large connection with a blue cap, but I feel like that cap is supposed to be there.
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Discussion Starter · #14 ·
Yes, my car is a regular fullsize LTD; it has the C4 transmission.

The not so good news is, I do not have that calibration sheet.
Dang. Any chance you have something vaguely in line with what my car is (if there's even anyway for you to guess that)? I figure anything is better than nothing. The car was original sold in Indiana in July of '77 if that helps?

The black cardboard corrugated hose goes to the air cleaner.
That is connected (though not air tight thanks to what I can only assume was a very rude mouse).

The vacuum line goes to the carb, I think. It may have an inline valve.
All the vacuum ports on the carb appear to be attached to something already. One runs to the same funky connector as the red highlighted vacuum line from a previous picture I posted.
 

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Discussion Starter · #17 ·
No problem. You are going out of your way to provide me with help completely free of charge. I am in no rush, and it is much appreciated.

I can report that changing the fuel filter made no difference, so that can be ruled out. I also switched back in my old accelerator pump since the new one kept leaking. The new one had a double-layer design and upon removing it, I found the outer layer had already completely disintegrated in the week is was on the car. Unsurprisingly, the leaking went away after putting the old one back on.
 
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