BB-1 carburetor

[dl456]

Hello, 

I have a 22 Buick 6 and currently running a BB-1 in lieu of the Marvel. This is going together

as a runner and not a restoration. Restoration may come later.

When running on the vacuum tank, it runs out of fuel in the carburetor bowl on a long period 

under load. A long medium grade.

I have fixed this issue by installing a low pressure electric fuel pump. Runs great!

I seem to remember that gravity feed needles were available for the BB-1. 

Was I mistaken or is this the case? I would like to go back to vacuum tank supply if possible.

Thanks,

Dennis

 

[Mark Shaw]

Dennis,

    BB1 carb parts a very hard to come by....  If your vacuum tank cannot keep up, you probably have a vacuum leak in the system.  Often, the pot metal vacuum tank lid becomes porous and leaks vacuum.  I suggest you first try sealing the inside of the lid with airplane dope or gas tank sealer.  

[dl456]

Hello Mark,

The vacuum tank is rebuilt and tested. It's not a matter of keeping up but rather the head pressure from 

the tank moving the needle fully off of it's seat to replenish the carburetor float bowl. This only happened during long periods

of load. 

A low pressure electric pump cured this issue.

I don't believe the needle and seat in the carburetor is correct for gravity feed and was hoping maybe I could 

find one that was.

Thanks,

Dennis

 

[carbking]

Four different orifice fuel valve seats were available for the Carter type BB-1 carburetors.

 

Interesting that the valves specified in the universal replacement Carters (245s,sd, BB1A,D, 289s,sd) were all sized for fuel pumps. We ask our customers the application when kits are ordered for these carbs.

 

Most parts for these carbs are available, just not ala carte.

 

These are probably the most popular aftermarket carburetor for older cars, and the one most often misapplied.

 

Using a BB-1 with too small an internal venturi will cause venturi air velocity to be too high, creating a greater requirement (read WASTED) for fuel than the proper sized carburetor.

 

Jon.

Edited October 19, 2020 by carbking (see edit history)

[dl456]

Hello Jon,

I was hoping you would reply.

Looks like I'm out of luck on the Fuel Valve??

I have read my plugs after about twenty miles and they are light gray and

appear to be good. Performance on the pump is excellent.

Would this alleviate concerns about venturi size or should I be checking further?

Thanks,

Dennis

[stakeside]

I have been educated on the BB-1. I purchased a BB-1 with the kit and found it was for a fuel pump car. Since I am running vacuum tank the carb would not run properly. 

I am looking for the correct fuel valve. Are they available? Can a fuel valve be modified with a larger orffice?

Well, things did turn out quite good. I was able to have my original Steward carb rebuilt by Meyers Parts. They did a great job and my truck runs very well. That carb definitely looks good on the truck.

O Ya by the way I still have a rebuilt BB-1.

 

 

[carbking]

Dennis - if you are happy with the way it runs,..........................then you are happy with the way it runs, don't "fix it"!

 

I sometimes tend to be too much of a perfectionist with carburetor selection; but the proper internal venturi will allow best performance, regardless of the type of fuel delivery system.

 

Stakeside - fuel valve orifices sometimes may be enlarged on a lathe, provided the "needle" will still function properly. Check the diameter at the maximum of the pointed area of the needle.  One does not wish the needle to "stick" in the seat from a diameter that is too small.Remember to use a thicker seat fiber washer to compensate for the added distance the needle is inserted into the orifice on its taper. Always best to NOT adjust those old floats by bending. The thickness of the seat gasket can take care of most adjustment. I am rapidly running low on EXPENSIVE floats because folks ignore this advice.

 

Jon.

[dl456]

Jon,

Yes, i am happy with the way it runs. I will at some point be returning to vacuum tank delivery.

I have many period carbs at my disposal.  Your opinion: Would you rebuild a Marvel (as equipped)

or recommend a good replacement?

If I can be nosy/ curious ( it's my nature) What criteria is used in determining proper venturi size?

Is it CID , carb throat, intake manifold or a combination ?

Thanks for your patience,

Dennis

[carbking]

Dennis - would I rebuild the Marvel? NO!, but a number of folks do rebuild them, many of whom frequent these forums, and seem happy with them. (Of course some wag, and I cannot find the citation, stated "bologna tastes good if you have never had steak")  The only way I would personally leave a Marvel on any vehicle I owned would be if the vehicle were a numbers-matching (or all original) show/museum vehicle that was never started. Again, my personal opinion, for which you asked. Others have differing opinions.

 

If it were mine, and I wished to drive it, I would do some research, and equip it with either an SF series Stromberg or a 63 series Zenith of the appropriate size.

 

The criteria for determining proper venturi size can be a sliding slope. But the method I use (99 percent of the time) is to look it up (yes, I am lazy).

 

If one has a vehicle made in the USA, Stromberg or Zenith PROBABLY offered a replacement carburetor which was sized, selected, and TESTED by an engineer working on the project. Since I am the current caretaker for these records, I look up what the engineers determined to be a good fit at the time the vehicle was new.

 

In the unlikely event, that neither Stromberg nor Zenith offered a replacement, it becomes a set of "20 questions" (actually a few less), to include: engine design, CID, RPM, vehicle mass, number of cylinders, eventual application (Sunday afternoon, modified show, vintage racing.....etc.) and multiply by the square root of the big oak tree in my back yard   In other words, there is no hard and fast rule that always works.

 

Jon.

[Guest]

I am not sure if I agree with Jon 99.9% or 100% of the time but I do know that I am lucky with the Marvel Carb on my Pontiac.  At 100,000 miles, in 1961, when I had been driving it for 2 years the needle was worn where it connects with the float arm so it would flood or starve randomly.  The senior tune up man where I worked adapted a then currant needle to the float.  That lasted until about ten years ago when I had to make a new float.  So in my case the Marvel has been almost trouble free for 90 years and 500,000  miles.  I think beyond blind luck it is because the car was used daily.  I have a rebuilt spare on the shelf and used carbs from a '31  Pontiac and one from a '30 GMC with the same engine.  I tried both to see if they were worth keeping as a spare.  The '31 works but not well and the GMC one is wonderful up to 30mph.  The '31 came off a junk yard wreck and the GMC one is probably jetted for low speed operation.  Since I acquired the rebuilt one I will probably sell the other two.  I think sitting, not running and shade tree mechanics are the downfall of most old vehicles.

[Oldtech]

I don't think it's your carburetor. Old Buicks could run the vacuum tank dry on long pulls with lots of throttle just because they weren't making enough manifold vacuum. I think you already have the fix with your assist pump.  

[dl456]

Thanks to all for the comments,

Special thanks to Jon for sharing his experience and knowledge with  forum members.

I will run with what I have as I continue to sort the car. May experiment at a later date.

Not a fan of fuel pumps but the BB-1 needle seems to hold this pressure well.

 

Dennis

[dictator27]

Agree with oldtech.  Virtually any vacuum tank equipped car will run out of gas on an upgrade which is reasonably long because of low vacuum at the throttle plate.  Requires learning the fine art of feathering the accelerator while climbing hills.  🙂

[Mark Shaw]

20 hours ago, carbking said:

Re; sizing carbs... "engine design, CID, RPM, vehicle mass, number of cylinders",...

Jon,

    I am curious to know how the number of cylinders is factored in to carb sizing.  The intermittent flow characteristics for single and two cylinder vehicles must require some fudge factors to determine carb sizes.  I am familiar with net positive suction head and discharge dampening requirements for single and multiplex pumps (I sold them for years).  I am currently running a #245 SA BB1 on my two cylinder Model F Buick with good results.

[PFitz]

11 hours ago, Oldtech said:

I don't think it's your carburetor. Old Buicks could run the vacuum tank dry on long pulls with lots of throttle just because they weren't making enough manifold vacuum. I think you already have the fix with your assist pump.  

To add to that, some people lug the motor  at low rpm uphills. The lower engine speed, combined with the added load on the motor, drops the vacuum way down. If they have ever driven with a vacuum gauge hooked up, they'd see just how low the vacuum can get trying to maintain speed on a long hill in top gear. With some old engines it's easy to get near zero vacuum at full throttle on a hill. 

 

A downshift is needed on hills that are steep enough that it pushes the vacuum so low that the vac tank can't pull fuel. By downshifting, the transmission gives some mechanical advantage and speed back to the engine. That will get some load off the motor and thus raise the vacuum enough to keep fuel flowing.

 

Decades of driving them and I have never run out of fuel with a properly working vac tank fed engine on our long central NY hills.

 

Paul  

Edited October 20, 2020 by PFitz (see edit history)

[edinmass]

38 minutes ago, dictator27 said:

Agree with oldtech.  Virtually any vacuum tank equipped car will run out of gas on an upgrade which is reasonably long because of low vacuum at the throttle plate.  Requires learning the fine art of feathering the accelerator while climbing hills.  🙂

 

Excellent comment. A skill I learned and mastered at 16 years old. Not all cars need the throttle dance.....but most do. I’ll admit to learning this on my own, and figuring it out myself.......from standing on the side of the road! I climbed Mount Washington with a stock 1931 Caddy V-8, which feathering the throttle on a 7 1/2 mile 8 percent average grade was a big challenge! 

[carbking]

Mark - the oft-posted engine airflow requirement equation:

 

CFM = (CID x RPM) / 3456

 

More correctly, the equation should be written:

 

CFM = (VE x CID x RPM) / 3456 where VE is the volumetric efficiency of the engine (a decimal number less than 1)

 

But what is virtually NEVER mentioned is that this equation in either form assumes a four-stroke multiple cylinder engine of at least 4 cylinders (cylinder pulsing is important in the airflow calculation).

 

For four-stroke engines of less than four cylinders, convention is to multiply the resultant CFM from the above by 4 / N where N is the number of cylinders from 1 to 3.

 

And while I am sure you are aware of the following, some may not be:

 

The constant 3456, written for clarity, is 12 x 12 x 12 x 2. The three 12's are necessary to convert cubic feet (left side of equation) to cubic inches (right side of equation).

The 2 is necessary due to a four stroke engine having one intake stroke per 2 revolutions of the crankshaft.

 

Volumetric efficiency is where I tossed in the square root of the big oak tree in the back yard.  It truly is a "guesstimate"!

 

The figures I use, just from experience:

 

1970 Pontiac RA IV V-8 engine - 0.9

Most standard V-8 engines 1950's up - 0.85

Most post-WWII inline 6 cylinders - 0.75

Pre-WWII - 0.6

 

This is NOT an exact science, and exactly why, when possible, I rely on engineering data done when the cars/trucks were new.

 

Jon.

[carbking]

An example of looking up factory data:

 

Let us assume a prospective customer calls looking for a carburetor for a 1919 Stoughton truck with a Waukesha type BUX 4 cylinder engine.

 

A quick check of the database shows original carb was a Stromberg type M-1.

 

A somewhat slower check of the prints shows that Stromberg placed a venturi of 13/16 inch in the carburetor.

 

The M-1 is an excellent carb for the day, but expensive to rebuild, and the customer wishes to replace.

 

So I am looking for a more modern (less expensive) S.A.E. size 1 (from the M-1) carburetor with a venturi of appoximately 13/16 inch.

 

Simple.

 

Jon.

[WPVT]

Just to add my two cents. I had the same problem. When I took out the electric pump in a 1928 White truck and went back to the vacuum tank, the carb would run dry at higher rpm's. I did all the research I could, looking at inlet orifices, mostly relating to Model A's. I ended up drilling out the orifice in my carb. I found a numbered drill that just fit the existing orifice, then drilled it out with the next highest number. I say drill, but it was more like ream. I may have done it by hand actually. That did the trick. The fuel pressure from the gravity feed is so much lower than even a low pressure pump, that you need a larger orifice. A few thousandths makes a big difference. At least that was my experience, and it worked well.

[stakeside]

Do you recall the drill number that you used?

[stakeside]

Check the table:

 

[WPVT]

 I don't recall the number. What size worked for me might not work for you. If you have the inlet orifice in hand, go through your numbered drill set and see which drill fits the hole, ( which means the next size up won't fit). Then use the next size up to enlarge the hole.

That process enables you to gradually increase the orifice until it does what you want it to do. Just a few thousandths can make a big difference.

[WPVT]

Here's a copy of a post someone contributed a while back:

 

I was having difficulty in feeding my 1914 Overland 79T, running a later added-on Carter BB-1 Carb.  Fortunately before we were about to obtain an original carb for testing,  we stumbled across some Carter literature and discovered that Carter BB-1s could come with two different main inlet jet sizes (one for pressurized and the other (larger) size jet for gravity feed.  I may be off slightly, but the numbers were something like drill size 31 (.120" dia.) vs. drill size 39 (.0995" dia.) for the main jet.  We chucked up the main jet in a lathe and carefully enlarged the main jet to the larger size, since we were running a gravity feed system and then never looked back.  IIRC, there was something like a 40% increase in cross-sectional area for the fuel flow.  Suddenly no more problems running up hills or having to maintain a 3/4 full fuel tank.  I could now make full use of all 13+ gallons in the under front seat fuel tank.

 

My advice still holds however. Use your numbered drillset to gradually open up the orifice until you get the result you want. On my truck, it was sufficient to test the set-up by running it for 10 minutes at a very fast idle. With the smaller orifice, it would  run dry after a few minutes. With the enlarged orifice, it didn't.

 

Just to be clear, we are talking about the inlet valve orifice, not the main jet. When your engine quits, it's probably because the fuel bowl on the carb is empty. (Don't be misled by seeing fuel in the glass sediment bowl. That's always full.)  

As an additional note, I learned that turning over the engine with the starter was not sufficient to draw fuel into a dry vacuum tank. If the vacuum tank is dry because of sitting for an extended period, or because the main gas tank ran dry, you need to prime the vacuum tank with a little gas. Once the engine is running, there should be plenty of vacuum to fill the vacuum tank. So if you ever run out of gas on the road, you will need to re-prime the vacuum tank. Don't expect the AAA guy to know that !

[carbking]

There are at least four different fuel orifice sizes for fuel valves for the various Carter type BB-1 carburetors:

 

0.085

0.093

0.101

0.118

 

Be careful in boring these larger than the existing orifice. Some of the pointed area of the plungers will not seal an orifice larger than 0.101. CHECK BEFORE BORING!

 

Using the wrong size orifice can result in issues; both running out of fuel, or flooding.

 

Another issue that some find is the misapplication of which BB-1.

 

CARTER PRODUCED 70 DIFFERENT TYPE BB-1 CARBURETORS! Obviously these come in different flange sizes, but also different internal venturii sizes. Many refer to the many BB-1 carbs as a single BB-1. That is analogous to referring to a model T Ford and a Rolls Royce as being the same  After all, both are automobiles, and both have four tires that touch the pavement

 

The largest engine Carter recommended using ANY of the BB-1 was the 319 CID Packard, and that was the 289s superseded by the 289sd. We have found THROUGH ACTUAL TESTING that either a Stromberg SF-3 or Zenith 63AW12 with the venturi suggested by Stromberg works MUCH better on this engine.

 

Much as I like to adhere to information published "in the day", I really believe Carter was optimistic is this recommendation. Personally, I don't recommend any of the various type BB-1 carbs for engines larger than 290 CID.

 

Using the wrong venturi (in either direction) will NOT give optimal performance. Too large a venturi will result in the venturi air velocity being low, and the engine will run lean. Too small a venturi, and the venturi air velocity will be too high, resulting in higher than normal fuel usage, the possibility of "icing", and the possibility of the bowl running low on fuel, regardless of which fuel valve orifice is used.

 

EDIT: this link will explain the range of engine sizes a single carburetor can service, based on flange size and venturi size:

 

http://www.thecarburetorshop.com/Stromberg_SF_carburetors.htm

 

Probably someone has "successfully" used a BB-1 on a 600 CID engine, and will post about their success in this thread. If the individual is happy with the performance, then I am happy for them. Just remember the old saw (and I wish my memory were better to remember whom to cite) "balonga tastes good, if one has never tasted steak"!

 

Jon.

Edited October 23, 2020 by carbking (see edit history)

[John_Mereness]

To be blunt:  All these cars running around with Carter BB-1 Carbs that the owners will never expereince what their car can really do verses all the BB-1 crap they experiences. 

 

Below is the new Franklin solution

 

December 7, 2018.
Series 12 and 13 new replacement Zenith updraft carburetors.

Designed to replace the original potmetal Stromberg T-2 on all Series 12A and B, and all potmetal T-2, U-2 used to mid production Series 13. After many decades the original potmetal carbs are cracking and becoming unsafe to use as a result of intergranular corrosion. The potmetal used in the 1920's and early 1930's is porous. It is slowly corroding from within and expanding/cracking. 

These are new manufacture, diecast updraft carburetors have the correct size venturi and jetting for all Franklin Series 12A, B, and Series 130. Plus a model is available for the larger Series 135/137 engines. 

Features

• Bench set and ready to bolt-on updraft that uses all the original hand and foot controls.
• Simple and decades-proven design.
• Original air filter fits right on.
• Adjustable idle speed, idle air/fuel mix, and high speed fuel jet, that work the same as the tuning procedures covered in the Franklin Operator’s Manuals.
• Fuel-proof rubber tipped float needle for leak-free sealing when the engine is shutoff.
• Same 1/8 inch pipe thread as original fuel line inlet fitting.
• Vacuum controlled accelerator and power enrichment circuits.
• Dust seals an throttle and choke butterfly shafts.
• Comes with new mounting gasket, nuts, and lock washers.

Note, these are not stationary/industrial engine carburetors, like many that are turning up installed as replacements in the past. With these there is no need to over-adjust the main jet too-rich for cruising conditions so as to compensate for being too-lean during acceleration and hill climbing because previous replacement types lacked those fuel circuits. These are specifically designed and sized with all the correct fuel circuits needed to smoothly handle all Franklin driving conditions with the proper air/fuel ratios. 

For more info contact,
Place an inquiry out on the Franklin page - it will be answered

 

 

Edited December 5, 2020 by John_Mereness (see edit history)

[Mark Shaw]

On 11/29/2020 at 10:59 AM, John_Mereness said:

To be blunt:  All these cars running around with Carter BB-1 Carbs that the owners will never experience what their car can really do verses all the BB-1 crap they experiences.

John,

     You seem to be getting unnecessarily blunt and perhaps a bit ignorant about BB1 carbs.  I run BB1 carbs on my 08 Model F and 13 Model 31 Buicks with very satisfying results.  Both cars originally had beautiful brass Schebler carbs that would run well at idle or at full speed, but never both.  Not all Schebler carbs are bad, but these early primitive carbs with auxiliary air valves were often replaced with more modern venturi style carbs like the BB1. 

    Over the years, BB1 carbs were fitted on 15 different brands of cars & trucks as original equipment, but many more were fitted as aftermarket carbs to solve the limitations of original equipment carbs that didn't perform as well.  They were made with reversible linkage in several sizes to fit lots of different engines with adjustments not available in Scheblers and others.  However, the BB1 carbs are not always the best retrofit carbs either.  I do run Zenith Model A carbs on my 12 Model 34 and 15 C25 Speedster because they are sized right for the 165 cu in Buick engines, and are very simple and inexpensive.  I bought three from a Model A guy for only $15 each and rebuilt two using parts from the third.

Edited December 2, 2020 by Mark Shaw (see edit history)

[John_Mereness]

2 hours ago, Mark Shaw said:

John,

     You seem to be getting unnecessarily blunt and perhaps a bit ignorant about BB1 carbs.  I run BB1 carbs on my 08 Model F and 13 Model 31 Buicks with very satisfying results.  Both cars originally had beautiful brass Schebler carbs that would run well at idle or at full speed, but never both.  Not all Schebler carbs are bad, but these early primitive carbs with auxiliary air valves were often replaced with more modern venturi style carbs like the BB1. 

    Over the years, BB1 carbs were fitted on 15 different brands of cars & trucks as original equipment, but many more were fitted as aftermarket carbs to solve the limitations of original equipment carbs that didn't perform as well.  They were made with reversible linkage in several sizes to fit lots of different engines with adjustments not available in Scheblers and others.  However, the BB1 carbs are not always the best retrofit carbs either.  I do run Zenith Model A carbs on my 12 Model 34 and 15 B25 Speedster because they are sized right for the 165 cu in Buick engines, and are very simple and inexpensive.  I bought three from a Model A guy for only $15 each and rebuilt two using parts from the third.

Nope, BLUNT ON PURPOSE and NOT IGNORANT (leave them on the Chevy Step Van they came from)- Ignorance is the people who try to get them to work to find they lack proper speed ranges and ....  - first thing I replace on any car I buy (and I sell maybe 2 to 3 a year on ebay replacing them) - Yes, they did make large jet-ed/throat-ed ones, but they are rare as hens teeth.   I will concede that for smaller cars and smaller horsepower cars you usually can find one that works.  Just keep them off Packard's, Stutz's, Franklin's, Auburn's, and ....

[Mark Shaw]

21 hours ago, John_Mereness said:

Just keep them off Packard's, Stutz's, Franklin's, Auburn's, and ....

OK, will do.  I only have Buicks....

[ojh]

It'd be a tough call to say who made the better 'tube' style carb, Carter didn't make any junk, they were totally anal about the carb design and its' purpose but for versatility I'd go with the Zenith or Tillotson if you were swapping things around.  But, if you have an original application and the original Carter you won't improve on the Carter design as long as the engine has not been modified.

[Graham Man]

I run a Carter BB1 289SD on my 322CID 827 Graham-Paige, it will blow right past 70mph without hesitation, starts every time even after sitting for months.   I have never had a problem with a properly sized Carter BB1.   I absolutely agree, most BB1 carburetors were designed for small engine displacement and most owners never check to see if they have the correct size carburetor.  I also agree the original OEM carburetor is the best, but time has not been kind to many carburetors and a good replacement carburetors are the only choice.  I can not make the connection between a improperly sized carburetor being installed and that making it a bad carburetor?

 

Carter built carburetors from 1909 to 1985.

 

 

[DGTryon]

Basic physics involved here.  A carb designed for 3-5 psi fuel inlet pressure has a much smaller needle seat than one running on a vacuum tank (about 0.5 psi).  Hence the vacuum tank cannot supply the high fuel demands.