1953 Cadillac 60-Special "The Muskogean Phoenix"

[kudims]

Rebuilding the Vacuum Advance Unit for the Distributor

Next step in re-animation of the Muskogean Phoenix, was vacuum spark advance regulator. NOS is pretty expensive ($300), but the common problem is obvious and can be easily fixed within 1 hour.



I removed the vacuum advance unit, which was no longer holding vacuum. Carefully, I cut the crimped retaining ring and disassembled the mechanism.


Disassembly and Diagnosis

Upon opening the unit, I found that the 70-year-old diaphragm had "evaporated" into dust.
Luckily, I had a fuel-resistant diaphragm from a fuel pump (which I had to rebuild several posts ago), and it was a fair replacement for the broken one.





Installing the New Diaphragm

The new diaphragm was fitted into place, and as an extra precaution, I applied a small amount of polyurethane sealant under the rivet to ensure a tight seal.





Trimming the diaphragm to size is critical but should only be done after the unit is fully reassembled.

Why Wait to Trim the Diaphragm?

Attempting to mark and trim the diaphragm before assembly is a recipe for misalignment. The diaphragm is spring-loaded, and pre-trimming it makes proper assembly nearly impossible without factory conditions. It can end up either protruding or collapsing unevenly.

Modifications and Reassembly

Without the diaphragm in place, I drilled six 2.5 mm holes and tapped them for M3 threads. The holes in the outer plate were enlarged to 3 mm to allow the screws to fit freely.
The unit was reassembled with the diaphragm and spring, ensuring the diaphragm was properly seated. The screws were tightened securely, and the excess diaphragm material was trimmed cleanly using a sharp blade.










Final Result

The rebuilt unit looks and functions perfectly. With the addition of screws, the design is now fully serviceable for future repairs.







A quick vacuum test (using the highly technical "tongue test") confirmed that the unit holds vacuum.
The distributor's vacuum advance is now fully operational and ready for many more years of service.

[James Landi]

Your reconstruction is so IMPRESSIVE... congratulations-- I surmise that many folks simply ignore the vacuum advance, since their engines seem to run well. As many of us know, a good vacuum advance provides smoother start ups, snappy acceleration, and better gas mileage.


 I ran into this  issue about a decade ago, and had no idea that one could successfully restore an old one. The metal chamber was my non-starter.   Many distributors were used interchangeably by engine manufacturers and varied in geometry even though they "looked" identical. In my case, I took the plunge with a Corvair advance, and sure enough the actuator arm was an 1/8 inch too long. I shimmed it against the body of the distributor, and it has worked perfectly.  Bottom line, there's usually a work around, but it's never easy.   

[kudims]

Restoration and Adjustment of the Carter 4-Barrel Carburetor

I recently tackled the restoration of a Carter 4-barrel carburetor, often installed on Cadillacs with factory air conditioning. Unlike the more common Rochester units, Carter carburetors include a load compensation system for air conditioner operation, a unique feature that can help identify whether A/C was factory-installed or added later at a dealership.

Here, I'll share my experience with the restoration process, detailing the challenges and solutions, though it's likely of niche interest to most readers.

Overview and Cold Start System

The cold start system relies on a bimetallic spring and a series of linkages.

1. In cold conditions, the spring contracts, pulling the choke lever to close the air flap.
2. Simultaneously, other linkages slightly open the throttle plate to increase idle speed for warm-up.
3. As the engine warms, vacuum draws heated air through a calibrated tube near the exhaust manifold, expanding the spring. This allows the air flap to open under its weight and airflow pressure, gradually reducing idle speed.

The system also includes a small-toothed fast idle sector, which releases once the accelerator pedal is tapped, allowing the throttle plate to return to its normal position.








Throttle Linkage Adjustments

1. The accelerator pump linkage was incorrectly adjusted, causing the upper cam to hit the carburetor lid during deceleration and preventing the throttle from fully closing. This issue led to idle speeds fluctuating between 400 RPM and 600 RPM. A simple adjustment to the wire linkage resolved the problem, restoring consistent idle performance.

2. The fast idle linkage controls a cam that interacts with the fast idle screw during warm-up. It also blocks the secondary barrels from opening until the engine reaches operating temperature. My carburetor was missing its blocking pin, and the secondary throttle lever was damaged. These were repaired using a custom-made M3 brass pin and an M5-threaded secondary throttle lever stop.



Cleaning and Initial Inspections

The first evening was spent cleaning the carburetor inside and out. I used six cans of carburetor cleaner, scrubbing every nook with a toothbrush to remove deposits.







The throttle body showed no play, thanks to long bushings in excellent condition.





Common Issues Addressed

Primary and Secondary Float Adjustment: The floats were swapped, leading to improper fuel levels. Primary float levels were 12 mm below specification, contributing to poor performance in hot weather. Correct levels were set at 1/8 inch for the primary floats and 1/4 inch for the secondary floats per the service manual.












Hot Air Tube: The heat channel for warming the choke system was completely clogged with carbon deposits, disabling the system. This was cleaned thoroughly.


Idle Mixture and Throttle Stop: New ethanol-resistant float needles were installed, replacing the original metal-on-metal needles.



Final Assembly and Adjustments

Economizer System:

Installed economizer rods and linkages, ensuring smooth operation. These rods enrich the mixture during high-load conditions or when the accelerator pump is activated.









The adjustment was verified using feeler gauges.





Choke System:

Adjusted the choke flap with a 0.6 mm round gauge (used a drill bit for precision).







Verified the fast idle speed to ensure it stayed below 1800 RPM when the engine was fully warmed.

Secondary Barrel Lockout:

Tested the blocking mechanism to ensure secondary barrels remain locked until the fast idle mechanism is fully disengaged.















Idle RPM improver inspection and cleaning:




Carburettor is now fully assembled and ready to be installed:











This is not correct gasket orientation (should be flipped over 180 degrees), though it's how you want to orient it, if you do not want hot exhaust gases to travel through the bottom of the carburettor.



Results

After careful reassembly, the carburetor was reinstalled on the engine. Final idle settings were adjusted as follows:
- Neutral: 400–420 RPM
- Drive: 380–390 RPM
- Drive with A/C engaged: 420 RPM

The engine now runs like a Swiss watch—smooth, consistent, and responsive under all conditions. The Carter carburetor, with its unique systems, is fully operational and ready for many more miles of service.

[Lexi]

Wasn't 1952 the first year for mass produced 4 bbl carburetors? So your 1953 carb would be one of the first 4 bbl carburetors, which in itself is interesting from a historical perspective. Clay/Lexi

[kudims]

Wasn't 1952 the first year for mass produced 4 bbl carburetors? So your 1953 carb would be one of the first 4 bbl carburetors, which in itself is interesting from a historical perspective. Clay/Lexi

Yes,  1953 was a second year with 4bbl on Cadillacs. And adjustments differ between 52 and 53 for float levels, idle rich screws, and idle rpm

[Cadman-iac]

  I really like your posts, very well laid out and informative, like you would expect from a factory training program.
 Thanks for sharing your experience with these old cars.

 Rick

[The Tassie Devil(le)]

Restoration and Adjustment of the Carter 4-Barrel Carburetor

Love the skewed thread on the Choke Tube attachment point.  The person working on the engine must have known that something was wrong when they initially crossed the thread.  But, kept on going with his, or her, heavy hand.

Bruce.

[kudims]

Love the skewed thread on the Choke Tube attachment point.  The person working on the engine must have known that something was wrong when they initially crossed the thread.  But, kept on going with his, or her, heavy hand.

Bruce.

Yes, "bended" hands left their traces in many places

[kudims]

Fixing the thermostatic valve in the automatic heater system

The Cadillac is equipped with an automatic climate control system from 1953. It differs from what we're all used to today. Back then, "automatic climate control" simply meant maintaining a constant cabin temperature by adjusting the temperature of the air itself, without switching between heating zones or changing fan speed.

Nevertheless, just having a TEMP knob that let you dial in a chosen temperature—albeit calibrated in "abstract increments"—already set Cadillac apart from, say, Chevrolet.

By now, you might guess something was wrong with this system.

As soon as I tried moving the dampers and the temperature control—now at home, not in Montana—a blast of scorching air hit my feet and face, and there was no way to stop it. Even with the fan switched off, the incoming airflow felt like boiling-hot air on my legs.

It became clear the heater valve wasn't working.

Below are some pictures, along with my comments.



From the engine compartment side, removing the rubber cover from the thermostat-valve



Removing the thermostat-valve itself



This valve works on the same principle as a refrigerator relay (except the fridge relay closes an electrical circuit, while here it mechanically shuts off flow, but the principle is the same)

There's a valve inside that shuts off the flow. Control of that valve involves three things: the position of the temperature control cable (which adjusts spring tension), the springs themselves (one main spring, one adjustment spring), and the power element. The key to this automatic setup is really the power element, which is filled with refrigerant. More on that later, but let's fix what can be fixed first.



The valve stem seal was a bit old and needed replacing. I purchased this rubber part on a site specializing in 1953 Cadillac parts for $40. Later, I realized all these seals are identical (because they were all made by a single supplier, Ranco—provider of heater thermostats and valves for many car brands, including some European) and are sold elsewhere for $5. No big deal



Valve components: housing, stem with valve, seal, backing plate



Cleaning the mating surface



Installing the new seal and bending the tabs back to lock it in place



And here is the 'puck' that was completely dead—i.e., empty. Immersing it in water and blowing air through the tube revealed numerous tiny holes in different places



Annoying, but nothing to be done... I need to find a rebuild kit that basically doesn't exist">
Sure, you can get a so-called refurbished thermostat for a Cadillac at a price of $500+.
Researching the matter showed that similar thermostats—or more specifically, thermostats with a similar power element—were used in Studebaker and Packard vehicles of that era.



That same evening, after discovering the problem, I found a new-old-stock Studebaker thermostat on eBay for $125. So here it is. Of the entire mechanism, I only need the 'puck.'

Imagine my despair when, while trying to straighten the bellows tube, it cracked right where it had been pressed against the housing for many years. Out went the gas, and darkness fell... At that moment, I could've cried. Put yourself in my shoes, and you'll understand.

However, not even the Gods can make pottery without a few burns... So I grabbed my soldering iron, some flux, and sealed the crack.



Crack at the tube's bend point



For charging the gas, I made a little device out of a bolt. I drilled a 1/8-inch hole, inserted the tube, tinned it, and then threaded the other end into an A/C charging port to add refrigerant



3–4 bar is plenty. The power element starts working, and the second spring handles fine-tuning, which is adjusted by a set screw.



The end of the tube is sealed on an anvil. Then the bolt adapter is unsoldered, and the tube tip gets soldered shut.



The power element under pressure. This pressure opposes the springs, which want to keep the valve open at all times.



Cleaned the copper and fixed a dent in the fitting using the same technique I used to straighten the antenna cylinder in the previous episode.



Valve in the open position



And here it is closed. In intermediate positions, the valve can be partially open or closed, depending on outside temperature and the power element's internal pressure. That pressure changes with temperature. The principle is exactly like an engine coolant thermostat



Still, my success was short-lived. Once installed in the car, the tube finally gave out, showering me with green refrigerant. With the phrase *this is just wonderful*, I disassembled the valve again and slipped a suitably sized tinned steel sleeve over the area where the tubes meet. Then I charged the gas again and re-soldered the tube's end.



After numerous assemblies and disassemblies, one of the locking tabs snapped off.



I had to use a not-so-beautifully looking, but reliable solution.



Stainless steel screws in place



Mounted it in the car, attached the cable



Replaced the deteriorating foam gaskets on the dampers





The bellows tube goes into the air distribution box. Hot or cold air flows over it, causing the power element's pressure to increase or decrease. This makes the valve open or close. Obviously, the TEMP knob setting matters here.

Once it became a bit cooler in December, I did the fine-tune of the spring tension using that set screw so the midpoint on the TEMP scale corresponds to about 23 °C (74 °F) in the cabin.

[Cadman-iac]

  This is really interesting.  I've rebuilt the valve on my 56, and it's got a dual capillary tube on it. I had 3 valves to start with, one had one of the tubes broken off, one was apparently cracked and the gas had leaked out rendering it useless, but the 3rd one was still operational.
I happened to have a new valve for a 57 Chevrolet, so I took the seal and used it to fix the Cadillac valve. I wasn't aware that the seal is still available new. Would you be willing to provide a contact for these?
I really like your method of repairing the pipe, very ingenious. I don't recall how I straightened mine, it's been over 7 or 8 years since I did this.
What I found extremely interesting is that the capillary tube is repairable. I was under the impression that once the gas had escaped, you had to find another one.
If I may ask, can you post a picture or two of this modified bolt you used to recharge the tube?
I'm trying to figure out how you got the R12 hose to connect to it. This will come in handy if I should ever need to repair mine.
I do remember taking the tubes and straightening them using a 6-inch wide vise, and then carefully rolling them up into a loop until it was time to install it.
I think I posted something about it on here years ago, I'll have to try to find it again.
Thank you very much for posting your excellent process and experience with this, it's been a pleasure to read.

Rick

PS, would you know if the capillary tube and "puck" system used on the A/C thermostatic control also uses freon in it? I've done some work on mine to get the heating wire replaced on it and they solder the wire to the end of the tube. I had one blow out the gas while I was trying to solder a new resistance wire to it and had to find another tube for it.
Thinking about this, if you crimp the tube just below the sealed end, I think you should be able to solder the wire to it then without releasing the gas.
The wire uses the end of the tube as a grounding point and when energized it heats the tube to regulate the temperature.
I can't remember what the type of wire used is called, another member here (Jose Gomez) told me about it though and I was able to buy a roll. I posted my rebuild experience with it on here too, but it's been probably 3 or 4 years ago now.
If I had known that you could recharge the tube, it would have made the process a lot easier.
Thanks again for posting this.

Edit: after much searching I found the thread on the A/C
thermostat repair.
https://forums.cadillaclasalle.club/index.php?topic=171656.0

I'm still looking for the heater valve repair thread. Now I'm not sure if I posted a separate thread or added to an existing one.

 Are you sure you're not an instructor at a technical/trade school?

[James Landi]

Yikes!!!!you brought back many submerged memories...  When my auto adjusting valves failed (sometime in the early 1970's when I was daily commuting 90 miles), my work-around was a hot water gate valve near the firewall that blocked the coolant flow to the heater cores in the kick panels.  Neither convenient nor elegant.  You're patient and highly talented . Bravo! 

[kudims]

If I may ask, can you post a picture or two of this modified bolt you used to recharge the tube?
I'm trying to figure out how you got the R12 hose to connect to it. This will come in handy if I should ever need to repair mine.

You will want to take bolt 7/16-20 - this 100% matches the R12 connector thread. Drill a hole equal to the tube diameter + a little bit :-), solder it, and here we go. After you pump the gas, bend the edge of the tube near the bolt=connector with a thin hammer - it will already seal it. Then cut the tube, then solder the edge to keep it sealed forever

[kudims]

I happened to have a new valve for a 57 Chevrolet, so I took the seal and used it to fix the Cadillac valve. I wasn't aware that the seal is still available new. Would you be willing to provide a contact for these?

 Are you sure you're not an instructor at a technical/trade school?

Here is the seal you want to have in order to fix leaking valve
Link to ebay

And no, I am not an instructor, I am a Program manager in R&D in the largest Oil&Gas Service Company

[kudims]

Air Conditioner: Compressor.

I wasn't happy with how noisy the A/C compressor was. More precisely, there was a knocking sound (you can see it in the video at the end). Removing and repairing my own compressor is risky, because I could end up with nothing at all if something goes wrong.

That's why I picked up a similar 1954 compressor on eBay (no chance to find a '53 one). It's exactly like mine, but with one significant improvement: it has a split clutch assembly. In other words, the compressor doesn't spin constantly; it only engages when the pull-in solenoid receives a control signal. Otherwise, it's the same A4 model.

The seller listed it for $90; I haggled it down to $60 plus $120 for shipping (the baby weighs 80 lbs!). With tax, the total came to $197.

You can imagine my disappointment when I unpacked the box and saw a broken mounting ear.



General view of the *experimental* compressor



Broken ear. The housing is cast iron



Seriously?!



So what do I do with this beast now?



Such a shame

I wrote to the seller in a slightly annoyed tone: why charge $120 for shipping if you can't pack it properly? I asked for a refund. The guy didn't argue, apologized, and refunded the full $197.

Okay, it didn't hurt quite as much as at the very beginning. After all, I did get a housing to experiment with (I'd thought about putting a modern compressor inside this housing).

I started slowly tearing down the compressor to understand its internals (there isn't a single blow-up diagram anywhere, just a barely comprehensible cross-sectional drawing)...



Taking apart the two-disc clutch



So far, so good



No visible wear



The clutch fits onto the shaft in only one orientation (note the splines), because it also serves as an external balancer for the compressor's crankshaft



Rear side of the pulley. Nothing too alarming here. Not sure where the oil came from—could be the seal, could be the bearing in the clutch that leaked a bit



Quite dirty



All cleaned up



Removed the seal flange, and surprise: the seal popped out, and the compressor started leaking oil with bubbles!





The actual sealing is done against a polished copper-bronze surface
Bubbles coming up. That means the compressor is still holding pressure! And judging by its appearance, it's been sitting in someone's storage room for decades.



Puller for the neoprene seal





Seal removed



Inside, everything is impeccably clean, and the oil is clear

At that moment I realized there's no point in destroying this compressor. Quite the opposite: I should rebuild it and install it on the car. I had various ideas about the seal. You can buy a new old-stock seal for $300 (not kidding), but I started searching by size for alternatives and found nothing. So I decided to leave the seal alone. If the compressor was still pressurized, then the seal must be okay.




The actual sealing is done by a spring-loaded copper-bronze contact surface



Pressure plate cleaned up



Fresh oil. 1 quart is $18





Secured the seal flange with polyurethane sealant



All done

Next, I had to decide what to do about the broken mounting ear. I tried to find someone who could weld cast iron but had no luck.
However, as the saying goes, every cloud has a silver lining: I realized I didn't actually need welding. It's unlikely anyone could reliably weld an ear that would support this much weight.



Made this bracket from 1/4-inch-thick steel angle. It attaches via two extended 5/16-24 bolts directly into the holes that clamp the two halves of the housing together



Test-fitting. There's a gap below between the compressor and the bracket for the rubber mounts.



Then I cleaned the compressor down to bare metal, taped it off, and painted it matte black. Here's the clutch being reassembled. The bracket's painted with black hammered-finish enamel and attached with two new high-strength bolts.



Ready to be installed



Bracket looks like it's original



With the compressor hanging upside down, some oil drained out. After installation, I'll fill it with fresh oil. The manual says it needs 16 ounces, i.e., a full pint (about 480 ml).



To remove the old compressor and install the new one, we laid a thick wooden block on top, strapped the compressor to the block, then my son and I lifted the block and extracted it. We reversed the steps to install the new one.



Mounting the clutch, filling with oil, hooking up all hoses



Pressing this little nub releases the clutch



Had to open up the solenoid and polish the contacts, otherwise it wouldn't engage—just sparked.



Looks awesome, doesn't it?



70-year-old technology">

The system is quite clever: the compressor's flange connections each have built-in valves. You close them, and the system pressure doesn't bleed off (remember, it holds more than 7 pounds of Freon!). Then, after installing the compressor, you open the high-pressure valve first and vent the air from the compressor (tested with a lighter—yes, really, that's in the Workshop manual). After that, you open the low-pressure valve. So, it means that you don't need a vacuum pump for this procedure.

I had to top off the system with a bit more Freon. I have R12 and the charging manifold with gauges for it.
The new old compressor runs quietly and pumps great. Ice-cold air blows from the vents. Mission accomplished once again.

And finally, here's a short video recap.

[James Landi]

BRILLIANT!

[Lexi]

Air Conditioner: Compressor.

I wasn't happy with how noisy the A/C compressor was. More precisely, there was a knocking sound (you can see it in the video at the end). Removing and repairing my own compressor is risky, because I could end up with nothing at all if something goes wrong.

You may want to check my comments on this 1953 Cadillac booklet on Air Conditioning: https://forums.cadillaclasalle.club/index.php?topic=171148.msg534793#msg534793

Clay/Lexi

[Lexi]

Here is the booklet I was writing about. Clay/Lexi

[kudims]

Here is the booklet I was writing about. Clay/Lexi

I have this book. Not very helpful compared to 1953 shop manual, half of which is devoted to A/C unit

[Lexi]

Never know what will or will not assist. I believe the Cadillac Roundtable training aids began about 1952, and I would imagine that if there were a set for 1953, there would almost certainly be an issue devoted to the new world of automotive AC. Perhaps if someone has such an issue, should it exist, they could share it with us. Clay/Lexi

[kudims]

Never know what will or will not assist. I believe the Cadillac Roundtable training aids began about 1952, and I would imagine that if there were a set for 1953, there would almost certainly be an issue devoted to the new world of automotive AC. Perhaps if someone has such an issue, should it exist, they could share it with us. Clay/Lexi

I still want to find time and disassemble my original unit. But before that I need to find and buy another '53 compressor. The probability to build 1 out of 2 much increases 😀