Looking for Quality Carburetor Rebuild for ‘42 Century

[JimH56]

Do any of you knowledgeable folks have a referral to a shop who can rebuild my ‘42 Century’s two old carburetors? I tried a rebuild kit myself but was unsuccessful. The car had difficulty accelerating and we get backfires and pops from the front carb when the gas pedal is punched. We think it is fuel starvation associated with the accelerator pump and/or high speed jets. Old Parts Source located in NJ used to rebuild but no longer as of a couple months ago. I am trying to find someone experienced enough with these carburetors to assist. Thank you for any suggestions.

[carbking]

Are your carbs Carters or Strombergs?

 

Jon

[JimH56]

Carter. 533S

[carbking]

Did you check the metering rod adjustment when you rebuilt the carb? Other than that, not much that can go wrong.

 

Jon

[JimH56]

I will check the metering rods. The symptoms are that the engine hesitates and coughs when accelerating and will pop and backfire when the throttle is advanced when you try to increase speed. 

[m-mman]

I feel the need to repeat Carb King’s mantra that I wish I had learned many years ago.  
“90% of carburetor problems are electrical….”

 

What is the condition of the rest of your ignition system?

 

[carbking]

m-mman - I think this one may be a sticky valve, or the distibutor not advancing; but the OP feels it is fuel. If the carburetor is at fault, it is probably the metering rod adjustment; although the float is a possibility.

 

Jon

[JimH56]

We think electrical is fine. Electronic ignition. Good plugs and wires. Timing set properly. Going to check vacuum for valve issues. We hope it is the high speed circuit.

[JACK M]

29 minutes ago, JimH56 said:

We think electrical is fine. Electronic ignition. Good plugs and wires. Timing set properly. Going to check vacuum for valve issues. We hope it is the high speed circuit.

I see a clue in this statement.

[JimH56]

What clue do you see?

[old car fan]

Electronic  ignition?

[JimH56]

Yes, 12 Volt, electronic ignition 

Edited October 22, 2023 by JimH56 (see edit history)

[old car fan]

Why.

[JimH56]

I’m looking for recommendations for a shop that can rebuild my carburetors. If anyone has a recommendation, it would be appreciated. Location can be anywhere, since the items can be shipped.

Edited October 22, 2023 by JimH56 (see edit history)

[old car fan]

Location?

[edinmass]

Electronic ignition and a 12 volt conversion are seldom done correctly. Coil polarity, incorrect fuel pressure, worn distributor bushings, the list is endless. Adding an electronic ignition is NOT an improvement. Modern fuel issues and incorrect plugs that don’t adjust for modern fuel, advance curves, put it back stock. When diagnosing a car one shouldn’t guess, it should be a thorough process starting first with mechanical, then electrical, and finally fuel. With the symptoms you posted, it should be a simple diagnosis for an experienced pre war car mechanic. Less than 15 minutes should pin point it. Buicks literally drove BILLIONS of miles with six volt systems for decades and were reliable. I would look hard at the ignition system.

[JimH56]

Thanks.

[TTR]

16 hours ago, edinmass said:

Electronic ignition and a 12 volt conversion are seldom done correctly. Coil polarity, incorrect fuel pressure, worn distributor bushings, the list is endless. Adding an electronic ignition is NOT an improvement. Modern fuel issues and incorrect plugs that don’t adjust for modern fuel, advance curves, put it back stock. When diagnosing a car one shouldn’t guess, it should be a thorough process starting first with mechanical, then electrical, and finally fuel. With the symptoms you posted, it should be a simple diagnosis for an experienced pre war car mechanic. Less than 15 minutes should pin point it. Buicks literally drove BILLIONS of miles with six volt systems for decades and were reliable. I would look hard at the ignition system.

Exactly. 👍
Not to mention countless other brand automobiles/equipment/vehicles/etc in past 100+ years with TRILLIONS of miles & hours successfully having used and many still using 6V systems.

Edited October 22, 2023 by TTR (see edit history)

[JimH56]

Certainly if one does not know what they are doing, or if the work is done incorrectly, there is likely to be a problem (or several) in virtually any endeavor one undertakes. If properly done, however, the debate and criticism of 12v versus 6v strikes me as illusory and likely based primarily upon anecdotal experience. I assume some are critical of MSD ignition systems as well, but those doubters are on the wrong side of the facts and reality.

[edinmass]

I would humbly and politely suggest that doing a conversion from 6 to 12 V or conversion to electronic ignition is already being done by somebody who doesn’t know what they are doing because there’s no reason to do it. Certainly neither conversion is done for reliability.  They are done because people don’t know how to properly fix or service the  original systems. As many people comment it’s a solution looking for a problem that doesn’t exist. Especially on a 42 Buick that was 100% reliable and well engineered when new by the largest company in the world that virtually invented modern engineering. 

Edited October 22, 2023 by edinmass (see edit history)

[JimH56]

19 minutes ago, edinmass said:

I would humbly and politely suggest that doing a conversion from 6 to 12 V or conversion to electronic ignition is already being done by somebody who doesn’t know what they are doing because there’s no reason to do it. Certainly neither conversion is done for reliability.  They are done because people don’t know how to properly fix or service the  original systems. As many people comment it’s a solution looking for a problem that doesn’t exist. Especially on a 42 Buick that was 100% reliable and well engineered when new by the largest company in the world that virtually invented modern engineering. 

Thanks for sharing your views. There may be no reason in your opinion to switch. Fair enough. But sometimes one acquires a nice vehicle where the conversion was previously done and done correctly. In that case, I believe the correct trope is “don’t fix what ain’t broken” (even if one believes it wasn’t broken in the first place, which I think is your point).
 

There are many purists in every hobby and strongly held opinions abound. I’m not sure your opinion that conversions are done because people do not know how to fix or service the original system accurately describes the universe of reasons and motivations, or even the most prevalent reason. For starters, if someone is smart enough and capable enough to correctly convert the system, the assumption that the person can’t or doesn’t understand the original system is, in my view, a dubious one. 

 

Your point is likely well taken when applied to backyard garage hacks who lack knowledge, experience and resources, and who store their cars on concrete blocks. But there is lots of literature taking the other side of the issue. 

[Matt Harwood]

My '41 Limited starts every time like it does in this video, hot or cold, even after sitting for months. It pulls like a freight train and runs at 65 MPH without issues. It didn't always do that but once I put everything back to factory specs, it worked like it should. I had too much timing so it bucked at low speeds. I had the wrong spark plugs in it so it idled rough. Dwell was way too short so the spark wasn't hot enough. Once I fixed all that, it ran perfectly and I wouldn't hesitate to drive it anywhere. It's still 6 volts and still running points ignition. It drives like a million bucks.

 

 

I don't think anyone is saying electronic ignition isn't a good invention, but on pre-war cars it seems to create ghosts that are hard to find, as you're discovering. Grounds can be problematic, so start by cleaning all the grounds and making sure the distributor is properly isolated. If you're using Pertronix, make sure it's getting a full 12V and isn't bleeding energy anywhere (like powering it from the ignition switch, which is a mistake). Make sure you have the right plugs and they're gapped properly (I think the manual calls for .025 to .027). And did mention check your grounds? That's really critical on an old car. 

 

Personally, I'm not a fan of electronic ignitions on these cars as they never seem to work as advertised. On a later car like my wife's '66 Mustang it made a tangible improvement, but I haven't seen a single pre-war car that actually benefitted from an electronic ignition without a whole lot of problems coming along with it. And 12-volt conversions involve a whole can of worms. Wire size, regulation type, alternator noise, grounds, things like that can create problems that are very hard to diagnose. Unfortunately, people do the conversion and assume that the source of any problems must therefore lie elsewhere. You're saying your conversion was done right, but you're still having issues. Discounting the conversion work as the source will not help you solve the problem. At this point, ALL systems are suspect.

 

Ed's advice is good and it doesn't come from being a purist. Put it back to stock and it should run like it should. Period. That might involve undoing a lot of work, but if the goal is making it run right, then it will be worth it. Yes, technically it all should work with the modifications, but obviously it doesn't. There's a ton of troubleshooting that will be involved and sadly, with a modified car, none of the procedures in the (very helpful) shop manual will apply. So you're shooting in the dark. You've already had advice on the carburetor from the best in the business and the adage that 90% of carburetor problems are ignition isn't too far off. But with the modifications, you're fighting a battle on two fronts and it seems like you're assuming that the modifications are fine and looking for a problem elsewhere. That kind of assumption is what Ed is telling you to avoid.

 

Anyway, lots of people have problems with their old cars. And in virtually every case, they're cured by putting it back to how the factory designed it. We think we're smarter than those guys because we have 80 years of technology on our side, but I've learned that they were awfully smart and if they did something, they did it for a reason. Trying to outsmart them is often an exercise in frustration and frequently an exercise in futility. I'd lump the electronic ignition into that category--just because it's newer doesn't mean it's better. 

 

You seem to be taking Ed's advice personally and getting defensive. Don't. Be open-minded enough to recognize that the problem can certainly be due to the modifications, and statistically, it's more likely than you think. To paraphrase Sherlock Holmes, double check EVERYTHING. Eliminate potential problems. Whatever remains, however unlikely you think it is, must be the issue.

[Dave39MD]

What's wrong with concrete blocks?

[Ben Bruce aka First Born]

JimH56, I am on your side.  Lack of fuel is my guess.  Probably BEFORE the carbs, though.

 Most of these " 6 v" guys were not even born in the 6v era. I was there. 12V was ONE of the many things I was glad to see improved on.

  I believe your problem is fuel.  Plugged filter, perhaps?

  Ben

[JimH56]

Matt, you are correct that all systems - mechanical, electrical and fuel - must be checked and verified as operating correctly. Grounds must be solid, etc. I’ve been there and done that on my other cars, so you are correct on that.

 

I’m told that pops up the carb are a classic symptom of a too lean mixture or insufficient fuel, although there are certainly other possibilities, both mechanical and electrical.
 

I am just looking for a referral for assistance with a carb rebuild. 

[Matt Harwood]

Pops through the carburetor are usually an ignition problem but if you need a carb rebuild kit, Carb King can supply you with the best quality carb kits on the market. The Carters aren't particularly complex to rebuild, with the big thing being that they're thoroughly clean and that the parts fit correctly--the bodies and tops are machined flat and the shafts turn smoothly on their bushings. Other than that, it's just assembling a puzzle.

 

 

Edited October 22, 2023 by Matt Harwood (see edit history)

[Grimy]

1 hour ago, Matt Harwood said:

Pops through the carburetor are usually an ignition problem but if you need a carb rebuild kit, Carb King can supply you with the best quality carb kits on the market. The Carters aren't particularly complex to rebuild, with the big thing being that they're thoroughly clean and that the parts fit correctly--the bodies and tops are machined flat and the shafts turn smoothly on their bushings. Other than that, it's just assembling a puzzle.

 

 

"Pops through the carburetor" also denotes a lean condition.  I'd check vacuum hoses and the vacuum advance diaphragm.

[Grimy]

Afterthought:  leaks in the vacuum wiper system can cause a lean condition.  Cap off the vacuum feed to the wipers and test drive.

 

As to vacuum advance, see if the advance will hold a vacuum applied by a Mity-Vac or other such tool.  And while you're at it, check the advance weights to see that their movement is not impaired by congealed grease.

[31Buick96S]

On 10/20/2023 at 2:17 PM, JimH56 said:

Do any of you knowledgeable folks have a referral to a shop who can rebuild my ‘42 Century’s two old carburetors? I tried a rebuild kit myself but was unsuccessful. The car had difficulty accelerating and we get backfires and pops from the front carb when the gas pedal is punched. We think it is fuel starvation associated with the accelerator pump and/or high speed jets. Old Parts Source located in NJ used to rebuild but no longer as of a couple months ago. I am trying to find someone experienced enough with these carburetors to assist. Thank you for any suggestions.

The Old Carb Doctor, 1127 Drucilla Church Road, Nebo, NC 28761. Phone 800-945-CARB (2272). The owner is named Jeff Dreibus. I found him to be a pleasure to speak with and communication throughout the process was impeccable. The carburetor had some internal problems that Jeff found and corrected, that were well beyond the scope of a rebuild kit. Full disclosure, I haven't had the car running since the carburetor was returned, due to other priorities, but I look forward to some shop time this winter.

[carbking]

Jim - I asked about the make of carburetors due to each having their own "gotchas".

 

The Carter "gotcha" is the adjustment of the metering rods. You suspect the high speed circuit. If the adjustment on the metering rods is too low, then the high speed circuit, of which the metering rods are a large part, would be too lean.

 

We have been sending folks needing a rebuild to a company called Carburetor Specialist in Georgia. So far, I have had no negative feedback.

 

But if you are convinced the issue is fuel, then a fuel pump test to determine if the proper amount of fuel is available to the carburetor would be the first step.

 

IF the fuel pump passes the fuel volume test, the next test would be to test the function of the accelerator pump (MUCH more likely to be the culprit than the high speed circuit for a backfire on acceleration).

 

If the accelerator pump tests good, then remove the fuel sight plug and verify that the fuel level in the carburetor is correct.

 

If the fuel level is correct, then do the "run" test you have been running, and again check the fuel level when the engine stalls.

 

And a wee bit of comment concerning this thread. A friend on another forum has a signature of "wag more, bark less". Because you posted on this forum, I am "wagging" and trying to help, including the answer on a professional shop. Had you called my shop with your symptoms, MY first question would be do you have an electronic conversion on the vehicle? If the answer is yes, my next comment would have been that I unable to help until the points and condenser has been installed. WHY, you may ask? Because trying to debug a "carburetor issue" on an electronic conversion is a total waste of my time. I won't try to talk you out of the electronic whizbang, but when something goes wrong, it simply adds an additional degree of uncertainly; and much more often than not is the culprit. Fix the problem, then if you want the electronic gizmo, go for it.

 

One other thought: When you rebuilt the carbs, were the accelerator pumps in the kits you used leather or modern? If leather, then the skirt should be oiled with a light machine oil prior to installation, and the leather pump is probably good for 100k miles (or much more). The modern (reap CHEAP) neoprene accelerator pumps can fail in a couple of DAYS if exposed to ethanol diluted fuel. I have opened up customer carburetors with the blue pump, found the blue material at the bottom of the pump well disconnected from the pump stem, and the fuel in the pump well is BLUE!

 

In any event, PLEASE post the issue once it has been found. We all learn by reading symptoms and solutions.

 

Jon

[Ben Bruce aka First Born]

5 hours ago, JimH56 said:

Matt, you are correct that all systems - mechanical, electrical and fuel - must be checked and verified as operating correctly. Grounds must be solid, etc. I’ve been there and done that on my other cars, so you are correct on that.

 

I’m told that pops up the carb are a classic symptom of a too lean mixture or insufficient fuel, although there are certainly other possibilities, both mechanical and electrical.
 

I am just looking for a referral for assistance with a carb rebuild. 

Folks , we have done it AGAIN.   All Jim asked for   was a referral for a carburetor  rebuild..  Plain and simple. 

 

Pete Phillips in Bonham, Texas, rebuilt one for me. Worked as well as possible on todays gas.

 

  Ben

[Grimy]

6 minutes ago, Ben Bruce aka First Born said:

Folks , we have done it AGAIN.   All Jim asked for   was a referral for a carburetor  rebuild..  Plain and simple. 

 

Pete Phillips in Bonham, Texas, rebuilt one for me. Worked as well as possible on todays gas.

 

  Ben

Ben, that's indeed what he asked, but several of us who believe that 90+% of all alleged carb problems are electrical remain unconvinced that he has exhausted the ignition possibilities, including our esteemed expert @carbking.

[edinmass]

Most interesting is the guessing games called out with “did you try or did you check”. With the change over to 12 volts and electronic ignition there are simply too many engineering and workmanship issues to just dismiss them off hand as “better”. Jon is certainly one of the top carburetor experts on the planet……..and I always listen to his suggestions. Personally, a good diagnostic routine is what is missing. I have made my living fixing cars for decades, and most of my efforts are on pre war cars. Simply too many half assed changes and swapped out parts and components cause unbelievable problems that most people simply can’t get their heads around. Is it mechanical? Is it electrical? Is it fuel? Is the problem in the stars, or in ourselves? As a professional mechanic and businessman I do NOT guess, I diagnose. Almost everyone here doesn’t have a fully equipped shop………so guessing and conjecture are part of their diagnostics routine. A five gas analyzer, a distributor tester, chassis dyno, and a hundred other tools are required to properly diagnose a problem. Fact is, with a fully equipped shop and a good technician, the problem can be figured out in less than half an hour, and probably fifteen minutes. Non experienced people’s observations are often simply wrong. A good oscilloscope, a quality shielded DVOM, external enrichment devices, are all basic equipment. As Carb King said, and I agree with 100 percent is to remove the electronic ignition. Think the Hall effect sensor is correct? Test it……..that’s right, you can’t because the aftermarket guys won’t tell you what logic they are running for base timing below 250 or 500 rpm’s. Have the coils been load tested and heated? How about condensers. Is there a resistor in the new 12 volt coils? More unknowns. Modern fuels require float and jetting accommodations. Altered fuel lines can cause starvation and vapor lock from friction and under hood temperature’s. 
 

Start with the basics. Check the compression and valves. If it’s sound mechanically, then move on to ignition. Simple step by step diagnostics. It’s NOT rocket science, I would expect a properly equipped tech would have it figured out quickly. Without patting myself on the back, I know I would have it figured out quickly. Experience is what fixes running problems. If you haven’t spent 10,000 hours in a shop and serviced thousands of cars……….your more often than not going to be in way over your head. Of the last fifteen distributors I have placed on my tester, only ONE was within specifications. Just one……….half were “a mile off”. Gee……wonder why it starts hard, breaks down under load, and skips at high rpm’s. Simply put, running problems on pre war cars aren’t that hard to fix……….best of luck on you journey fixing your issue……….Ed.

[JimH56]

Much of this discussion seems premised on the assumption that the electrical is a new addition and that the problem suddenly arose after the change was made, instead of cropping up literally years later, which is the actual situation.  But I wholeheartedly agree that a reasoned diagnostic approach is required. Fortunately I am lucky enough to have access to the sorts of shop diagnostic tools and equipment mentioned in some of these posts. I chuckle, however, at the claim that the problem could be discovered in 15 or 20 minutes by an experienced old car mechanic. 

[carbking]

10 hours ago, Ben Bruce aka First Born said:

Folks , we have done it AGAIN.   All Jim asked for   was a referral for a carburetor  rebuild..  Plain and simple. 

 

Pete Phillips in Bonham, Texas, rebuilt one for me. Worked as well as possible on todays gas.

 

  Ben

 

Ben - you are absolutely correct!

 

However, having a carburetor professionally rebuilt is EXPENSIVE!

 

A number of us feel that a bit of testing might determine that the rebuild is unnecessary, and are trying to help.

 

It may be that we should only answer the question asked.

 

Jon

[Matt Harwood]

The road to hell is paved with good intentions.

[Grimy]

11 hours ago, edinmass said:

Most interesting is the guessing games called out with “did you try or did you check”. With the change over to 12 volts and electronic ignition there are simply too many engineering and workmanship issues to just dismiss them off hand as “better”. Jon is certainly one of the top carburetor experts on the planet……..and I always listen to his suggestions. Personally, a good diagnostic routine is what is missing. I have made my living fixing cars for decades, and most of my efforts are on pre war cars. Simply too many half assed changes and swapped out parts and components cause unbelievable problems that most people simply can’t get their heads around. Is it mechanical? Is it electrical? Is it fuel? Is the problem in the stars, or in ourselves? As a professional mechanic and businessman I do NOT guess, I diagnose. Almost everyone here doesn’t have a fully equipped shop………so guessing and conjecture are part of their diagnostics routine. A five gas analyzer, a distributor tester, chassis dyno, and a hundred other tools are required to properly diagnose a problem. Fact is, with a fully equipped shop and a good technician, the problem can be figured out in less than half an hour, and probably fifteen minutes. Non experienced people’s observations are often simply wrong. A good oscilloscope, a quality shielded DVOM, external enrichment devices, are all basic equipment. As Carb King said, and I agree with 100 percent is to remove the electronic ignition. Think the Hall effect sensor is correct? Test it……..that’s right, you can’t because the aftermarket guys won’t tell you what logic they are running for base timing below 250 or 500 rpm’s. Have the coils been load tested and heated? How about condensers. Is there a resistor in the new 12 volt coils? More unknowns. Modern fuels require float and jetting accommodations. Altered fuel lines can cause starvation and vapor lock from friction and under hood temperature’s. 
 

Start with the basics. Check the compression and valves. If it’s sound mechanically, then move on to ignition. Simple step by step diagnostics. It’s NOT rocket science, I would expect a properly equipped tech would have it figured out quickly. Without patting myself on the back, I know I would have it figured out quickly. Experience is what fixes running problems. If you haven’t spent 10,000 hours in a shop and serviced thousands of cars……….your more often than not going to be in way over your head. Of the last fifteen distributors I have placed on my tester, only ONE was within specifications. Just one……….half were “a mile off”. Gee……wonder why it starts hard, breaks down under load, and skips at high rpm’s. Simply put, running problems on pre war cars aren’t that hard to fix……….best of luck on you journey fixing your issue……….Ed.

I am impelled to comment for the sake of those new to the hobby that to solve the *vast* majority of driveability issues in a 1942 Buick, one does not *need* five-gas analyzers, chassis dyno, and other expensive and sophisticated test equipment.  My good friend @edinmass also known as "Mr. Five Gas" to those who spend any time with him, surely is correct to use his existing sophisticated equipment to simplify diagnosis.  But we mere mortals without such magical resources can properly rely on a diagnostic logic tree and use more primitive equipment and techniques such as vacuum gauges, compression testers, timing lights, capping off vacuum wiper feeds, and visual inspection of distributor advance weights.  So before you google "auto mechanics with 5-gas and dyno and familiar with 1942 Buicks near me" try it the old-fashioned way if you don't have Ed's resources.

 

Further, we in the forums do in fact routinely ask "have you checked this or that" because in this case as in so many others presented here the OP has not explained what diagnostic measures have been employed thus far.

[JimH56]

Thank you everyone for your suggestions, comments and recommendations. All are appreciated.

 

Just to be clear, we are checking the electrical as well as mechanical, and we have not ruled out those as the root cause, although as a result of our analysis, we have not identified any issues associated with the ignition in our testing sequence. Also, the automobile operated fine for quite a long time with the challenged 12 volt before the current problem ever cropped up. Should I mention that the issue actually began after a carburetor rebuild? This is why we continue to suspect a carburetor issue, especially since we have moved through the electrical and much of the mechanical (that work is in progress). CarbKing's suggestion that the accelerator pump and related systems should be checked are right on point.

 

Needless to say, I would like to get my original set of carburetors rebuilt by someone with considerable experience so that I have a good spare set, which is why I reached out to you all for thoughts. Thanks very much again for the suggestions. 

 

We will figure out the problem. As some of you requested, I will try to let you know the result.

 

To repeat, none of what I have said means that the problem is not electrical, but I did get the sense that a number of you were assuming that the issues were triggered by some recent change. Of course, everything needs be checked, tightened, and grounded properly.

[edinmass]

Here is a test for you.......add propane to the suspect carb that is spitting, and see if the additional hydrocarbons stop/prevent the possible lean burn misfire that you are experiencing.  I have special equipment to do this, but a plumbers torch opened up full while not lit will provide enough fuel to show if it's a lean burn issue. I suspect it is not going to solve it..........but one never knows till you try. If you don't understand what I am saying, PM me and I can describe it in more detail. Obviously check for large vacuum leaks and plug the brake booster off to eliminate that possible cause. Do NOT add liquid fuel or starting fluid as a fire and or explosion can occur with that method.  Let us know how it works out. Ed

[edinmass]

George, would you go to a doctor that doesn't use all possible test equipment to figure out what's wrong with you? Fixing a running problem should be done with the scientific method. And FYI, a five gas machine is not overly expensive for the last 25 years. Back in the 80's they were 75K, today a portiable unit can be purchased for under 1500 dollars. I do understand the shady tree mechanic path..........but it often times results in unnecessary time and money spent. I do stand by the statement that it shouldn't take more than 20 minutes to figure out if it's mechanical, fuel, or electrical. We ran our two Duesenbergs last week for 700 miles over four days.........never missed a beat, and I never opened a hood. It was a great tour. Here is a photo taken from the back seat of J223......a Pebble Best of Show winner. It did three miles on dirt roads that same day......and comfortably cruised at 75-80 for hours on end. Drive them like you stole them!