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1922 Cadillac Fuel Pressure Question


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Hello!

 

I've got a 1922 Cadillac Touring and one problem I'm experiencing is that it seems to flood itself when the gas tank is more than 2/3 full. It seems the engine fuel air pump over-pressurizes the gas tank forcing gas into the carb, flooding it at stops (forcing me to rev the engine or it will stall) and then pouring all over the garage floor. This problem seems to be less severe when the gas tank isn't full.

 

Any tips? Is there an adjustment?

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Caution........do not drive the car with this condition. You should carry three Halon fire extinguishers when driving this car because of their propensity to burn to the ground.......and take your garage and house with it. 
 

You should install a pressure pop off valve, limiting tank pressure and helping to vent over aggressive air pumps. I also recommend an in line electric cut off switch with a impact sensor to shut the fuel off to the carburetor even if you still have pressure in the tank. A sunk float, or over pressurized system is a disaster waiting to happen on these cars. They burn ........a lot. And yes, I have owned countless early Cadillacs. 
 

also, in the event of a fire, remember to open the gas cap BEFORE you attempt to put the fire out, or it will be almost impossible to smother the fire with a pressurized fuel leak. If you need help with what I am explaining, PM me with your contact info. You have a fun car, but it has several bad habits that need to be attended to. Properly addressed, it’s a fun and safe car. Ed

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11 hours ago, edinmass said:

You should install a pressure pop off valve, limiting tank pressure and helping to vent over aggressive air pumps.

 

There is a pressure relief valve built into the 22 fuel line that is designed to open at 2 1/2 pounds (which you should be nowhere near in normal operation) 

 

It's a fairly easy modification to add a fuel cut off inline as per edinmass's suggestion - I put mine in just before the strainer on the frame rail and mounted the switch (with built in LED) just under the hand pump 

 

It took a lot to get mine to the stage of not puking fuel all over the place but when fettled correctly and warmed up you should be able to throttle it right down with no excess gas coming out the tubes... the float design on the carbs is awful to work with and gums up quite easily 

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There is an adjustable relief valve on the drivers side frame rail where the line connect for the dash pressure gauge.

This should be removed and bench set at 2-1/2 lbs.

I suspect you may still have float or needle and seat issues at the carb.

Dennis 

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Thanks for all the advice! I've ordered a couple of the Halon extinguishers (the extinguisher under the seat expired in 1986!) and will dig into that pressure relief valve. That sounds like a likely culprit and easier to check first than digging to the carb, although that sounds like it needs work too.

 

Thanks so much!

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Interesting....my 1914 Caddy didn't have a pop off valve from the factory. I didn't know the 20's cars had them. With their propensity to burn, a non powder fire extinguisher should be used, as the powder will ruin paint, damage a running engine, and make a mess that takes months to clean up. Having a good BRASS float is important....the cork units suck...........

 

 

PS - Sunnyjay.........looks like a very nice car. 

Edited by edinmass (see edit history)
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11 minutes ago, edinmass said:

Interesting....my 1914 Caddy didn't have a pop off valve from the factory. I didn't know the 20's cars had them. With their propensity to burn, a non powder fire extinguisher should be used, as the powder will ruin paint, damage a running engine, and make a mess that takes months to clean up. Having a good BRASS float is important....the cork units suck...........

 

 

PS - Sunnyjay.........looks like a very nice car. 

Thanks so much! I've only had it a few months and only started driving it now that it's warmer. I'll make check and see if I have a brass float if I need to dig into the carburetor.

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49 minutes ago, Sunnyjay said:

Thanks so much! I've only had it a few months and only started driving it now that it's warmer. I'll make check and see if I have a brass float if I need to dig into the carburetor.

 

Unless its been replaced it will be cork - there are urethane foam replacements that are available (https://www.classicandexotic.com/store/p-3876-cadillac-johnson-carburetor-float-1920-type-59.aspx) that can be made to work as well but i needed to shave a bit off mine to stop it sticking 

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2 minutes ago, hidden_hunter said:

 

Unless its been replaced it will be cork - there are urethane foam replacements that are available (https://www.classicandexotic.com/store/p-3876-cadillac-johnson-carburetor-float-1920-type-59.aspx) that can be made to work as well but i needed to shave a bit off mine to stop it sticking 

Good to know! That link says Type 59. Would it also work for my Type 61? Did they use the same float?

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About 30years ago, I realized that there would be something to gain in having these Cadillac Johnson carbs professionally rebuilt. No matter how well the car ran. Rebuilt by someone who is an expert on these particular carbs. My ‘24 ran well, but off came , and off went the the C.J.  carb. And yes , indeed, there were issues that  no one , unless intimately familiar with these things, would have noticed and rectified. Likewise, I had no problems at all with the carb on the ‘27 when I got it a few years ago. Same game, and Classic & Exotic Services found things needing attention. Money well spent, with a very quick turnaround. C&E has become Straight Eight, and I have a message in with them to see if they are still providing C.J. rebuild service. 
 

I feel confident in speaking for Ed , who also feels the same , and recommends the pro rebuild route. Then you don’t have to wonder whether there is something wrong with the carb, when there is something wrong with the car. There is an issue with the carb which you will encounter eventually. That is fuel percolation in a hot engine/hot carb condition. As you take off on a pleasant drive, the car will run beautifully until things warm up. You will have difficulty driving the car, shifting it, and keeping it running. The hotter the day, the more you will suffer. When you send the carb in, do whatever surgery necessary to de-couple the intake manifold from the direct exhaust heat, and block off the exhaust ports where they used to feed the intake manifold. Use steel plates. Also see if you can put an insulation block between the carb and the intake manifold. Happy car, happy driver.     -    Carl 

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I am relieved and truly OVERJOYED to report that Straight Eight is still providing the incomparable services that their previous iteration did. For all practical purposes, it really is the same company continuing with a different name. Bruce got back to me bright and early this morning, I guess another example of their prompt attention to their customers concerns. By the way, Bruce, who is a long time member of Cadillac and LaSalle Club , has a “nickname”, “Chip”, so this information to you lucky potential customers might avoid momentary confusion. Oh, I should also mention that Straight Eight no longer does interiors in-house, full automobile painting neither. They do , of course , paint the components they work on if you like, such as the absolutely superb job they did on the black distributor for my 1927 Cadillac.       -     Carl 

 

P.S. I should mention how pleasant it is to deal with these gentlemen. You get the feeling that your small job is just as important as a full restoration of a Duesenberg. 
 

P.P.S. This is probably a good time to talk some about these Cadillac Johnson carbs. One issue is that there is an unusually complex parallelogram float linkage. Any play in that linkage can throw things frustratingly out of kilter. Such critical tolerances, along with a bit of shaft bushing wear, could well go unnoticed by anyone just tinkering with the things. Left uncorrected, intermittent or occasional nasty habits will frustrate the driver. My old Cadillacs run strong and true on fine carburetors and distributors.

 

Since I have mentioned distributors, although not relevant to V63 and earlier Cadillacs, let me add a “very short” 🥴😂 introductory explanation. In brief, 🤔🙄, (I have written extensively elsewhere) : Beginning in 1926 Cadillac began using pot metal for certain critical components. In 1927 this practice afflicted even more pieces, and continued on for a number of years. This was acceptable, in that the parts certainly would have been durable over the expected service life, well beyond actually, of these soon to be obsolete cars. It would have been inconceivable that these cars would still be used 20, 30, 100 years later. Few survived the WWll scrap drives, luckily ours shirked their patriotic duty to our benefit and delight. As the decades passed, the pot metal began to weaken, expand , and consume itself. 1926 and continuing on for several years, the distributors used critical pot metal parts. Happy to go into detail again, but just for here and now, the degrading distributors may even suffer catastrophic sudden failure. Classic & Exotic/Straight Eight has reproduced all these components in durable  metal for our cars salvation. I, and quite a few owners of these cars , have wasted considerable amounts of time and money trying to fix our distributors. I believe I was approaching a thousand dollars, when I stumbled across C&E some years ago. Seems none of my fellow post-V63 owners had yet heard the good news either. Turns out that some very high end cars, some 8 cylinder Stutz, also Duesenberg “A” for example , use the same distributors . That is why C&E came to the rescue. We mere and humble Cadillac drivers are collateral beneficiaries ! Others using the same distributor likewise take advantage. Eight cylinder Oldsmobile of the period comes to mind. Likely others too.

 

All right. This really is meant to be further testimony to a phenomenal resource. All parts are available from Straight Eight, and I wouldn’t try to talk the experienced mechanic out of doing their own distributor rebuild. Many have tried in the past, extremely difficult without the now available parts. Included in new parts are bearing upgrades in addition to the pot metal upgrades. Another solution is to simply replace with 1937-‘39 , pre-vacuum advance Cadillac distributors. The earlier Cads actually run better with these later bulletproof, single point distributors. Probably are curved better for modern gasoline which is too high octane for optimal performance. That particular sentence i just wrote regarding advance curve is conjecture on my part, but the “plug and play” replacement option is also very inexpensive.

 

I have been at this during a limited discretionary time period . I will sign off for a moment without further refining and editing. Forgive me for any unintelligible awkward writing. I will come back later to massage clarity into some deficient babble.      -    CC

Edited by C Carl
Add P.P.S. (see edit history)
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2 minutes ago, C Carl said:

I am relieved and truly OVERJOYED to report that Straight Eight is still providing the incomparable services that their previous iteration did. For all practical purposes, it really is the same company continuing with a different name. Bruce got back to me bright and early this morning, I guess another example of their prompt attention to their customers concerns. By the way, Bruce, who is a long time member of Cadillac and LaSalle Club , has a “nickname”, “Chip”, so this information to you lucky potential customers might avoid momentary confusion. Oh, I should also mention that Straight Eight no longer does interiors in-house, full automobile painting neither. They do , of course , paint the components they work on if you like, such as the absolutely superb job they did on the black distributor for my 1927 Cadillac.       -     Carl 

 

P.S. I should mention how pleasant it is to deal with these gentlemen. You get the feeling that your small job is just as important as a full restoration of a Duesenberg. 

Thank you so much for the info Carl! I'll definitely use them. I have their mailing address and will be removing and shipping the carb to them soon.

 

Regarding the pressure relief valve. How do you know if it is set correctly? Is that something you need to bench test?

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5 hours ago, Sunnyjay said:

Regarding the pressure relief valve. How do you know if it is set correctly? Is that something you need to bench test?

 

do you ever see more than 2 1/2 pounds on the gauge? If so then it's not properly adjusted

 

In normal operation mine sits around 1 lbs unless you stab the throttle when it will peak 

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13 minutes ago, hidden_hunter said:

 

do you ever see more than 2 1/2 pounds on the gauge? If so then it's not properly adjusted

 

In normal operation mine sits around 1 lbs unless you stab the throttle when it will peak 

Good question, I'm not sure how trustworthy the gauge is, but at idle it never exceeds the 1/2 lb out mark, and at speed it never goes beyond 2lbs. I did examine the pressure release and it is tightened all the way up to max pressure. Eeek.

 

Cadillac Carl suggested I take the release valve out and clean it up, which I'll try next. Perhaps it's gummed up from years of infrequent use.

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