Stromberg series SF and SFM updraft carburetors

[carbking]

I am often asked "what newer replacement carburetor can I put on my older vehicle?".

 

While there are a number of different brands, series, and qualities of replacement carburetors; in my opinion (others will obviously have different opinions), the Stromberg SF and SFM (marine) series are at the very top of any list. My opinion was shared back in the day by many vehicle manufacturers, as after the introduction of the Stromberg SF series in 1932, MANY manufacturers asked Stromberg to offer specific replacements for their older vehicles. But Stromberg also offered all sizes of the SF and SFM series as universal carburetors with adjustable main metering jets and clamp-style throttle arms so the carburetors could be easily adapted to many different vehicles (the KEY is to choose the carb with the proper size internal venturi). The Stromberg SF/SFM series were not discontinued until 1968. From 1932 to 1968 is a pretty good run for any product in a field changing as fast as the automobile changed in that time period.

 

To assist the enthusiast, I have produced an article, much of the information taken from original Stromberg documents of which I am the present caretaker. The link to the article is:  http://www.thecarburetorshop.com/Stromberg_SF_carburetors.htm

 

Others will bring up the popular Carter BB-1 aftermarket carburetor which in of itself is a very good carburetor. However, the single venturi and the mechanical accelerator pump of the BB-1, at least to me, make it less desirable than the Stromberg.

 

Jon.

Edited September 17, 2016 by carbking (see edit history)

[maok]

Thanks mate! So generous of you to share your infinite knowledge.

[C Carl]

I'll second that , Moe ! Sentiments shared by all I am sure ! His Majesty Rules ! Thank you , Jon , you are the greatest ! A mere subject in the realm ,  old Carl

[maok]

It was so good that I want to ditch my BB1 in the bin and find a Stromberg SF..

[carbking]

I have updated the article to include pictures of the larger carbs (SF-4 and SF-5) plus some published CFM ratings by Zenith, which at the time was a sister company to Stromberg. The ratings are applicable to the Stromberg carbs.

 

Jon.

[ArticiferTom]

Ditto ,on excellent article .

[Graham Man]

On ‎9‎/‎17‎/‎2016 at 12:51 PM, carbking said:

Others will bring up the popular Carter BB-1 aftermarket carburetor which in of itself is a very good carburetor. However, the single venturi and the mechanical accelerator pump of the BB-1, at least to me, make it less desirable than the Stromberg.

 

Not sure everybody understands the problem with mechanical accelerator pump on an updraft carburetor.  When you pump the accelerator on an updraft with mechanical accelerator pump and the engine is not running, the fuel runs out of the carburetor..everywhere.  On a downdraft it is not a problem, the raw fuel goes down the intake.  I still run BB1 Carter carbs, I only start them with the choke, works great every time (from your advice, thank you).

 

The cost of the BB1 vs. the Stromberg alone should be enough to carefully consider the Stromberg (better get one soon before the prices go up)  Next time I need one I will be looking at Stromberg's

[PFitz]

The down side to that is,  it's easy to flood the motor with raw fuel when starting if you pump the pedal too much on a downdraft. Many updrafts have a drain hole - like Jon mentioned - in the base of the  carb right below the venturi and the main discharge jet. It's less likely to flood the motor with raw fuel.

 

Paul

Edited December 6, 2017 by PFitz (see edit history)

[Spinneyhill]

I have a Dodge 8 1930. It LOVES petrol but if I put my foot on the accelerator when starting, it is very hard to start. I use a touch of hand throttle and the choke if necessary (which generally gets pushed in fairly soon at the same time as a bit more hand throttle is added). While it likes petrol it doesn't like being drowned in it! The foot takes over once it is running evenly.

[woodyboater]

I'm presently working on two Gray Marine engines.  A Fireball and a Phantom, both pre-war and they came with dual Stomberg SFM-3 carbs.  The disassembly is proving a bit tricky and I can't find a manual for these carbs to help me.  Does anyone have or know of anyone that may have this?  I plan to order kits for all four of the carbs from The Carburetor Shop, which I think Carb King runs as I follow through the threads here.  My current issue is there are some brass plugs that look like they should come out for cleaning purposes.  They are very stubborn.  Manufacturers sometimes put a plug in and don’t want it pulled for ‘field’ servicing and I don’t want to force anything and cause irreparable damage.  The tags on the carbs are 44-37A and 44-38A if this is helpful. 

 

Thank you for any help you can provide!

 

Edited February 10, 2021 by woodyboater (see edit history)

[carbking]

I do not know what may have been printed for service in some of the O.E. shop manuals such as Waukesha, Hercules, or American LaFrance; but Stromberg did not print such a manual.

 

Stromberg printed 2 pages in their service manual which contain: one cut-a-way drawing (not exploded), adjustments, parts numbers, and a picture of all the parts. Stromberg placed the parts on a white sheet in an order in which they took up the least amount of space, and took the picture. No physical proximity of parts intended.

 

As far as the brass screw headed or hex headed plugs are concerned:

 

Remove the zinc alloy parts (the venturi), the float, and all springs. These are parts that would be ruined by heat. Now heat the casting in an ELECTRIC toaster oven just as hot as you can get it. Remove the casting from the oven, and heat the cast iron AROUND the plug with an acetylene torch (propane isn't sufficiently hot) until starting to show red. Do this for all of the plugs. Return the casting to the toaster oven, and heat as hot as you can get it. Turn off the oven, and allow the casting to completely cool. DO NOT QUENCH. Remove the casting from the oven, and remove the plugs.

 

Jon.

Edited February 10, 2021 by carbking (see edit history)

[woodyboater]

9 hours ago, carbking said:

I do not know what may have been printed for service in some of the O.E. shop manuals such as Waukesha, Hercules, or American LaFrance; but Stromberg did not print such a manual.

 

Stromberg printed 2 pages in their service manual which contain: one cut-a-way drawing (not exploded), adjustments, parts numbers, and a picture of all the parts. Stromberg placed the parts on a white sheet in an order in which they took up the least amount of space, and took the picture. No physical proximity of parts intended.

 

As far as the brass screw headed or hex headed plugs are concerned:

 

Remove the zinc alloy parts (the venturi), the float, and all springs. These are parts that would be ruined by heat. Now heat the casting in an ELECTRIC toaster oven just as hot as you can get it. Remove the casting from the oven, and heat the cast iron AROUND the plug with an acetylene torch (propane isn't sufficiently hot) until starting to show red. Do this for all of the plugs. Return the casting to the toaster oven, and heat as hot as you can get it. Turn off the oven, and allow the casting to completely cool. DO NOT QUENCH. Remove the casting from the oven, and remove the plugs.

 

Jon.

Thanks Jon!  I will give it a shot.  Thankfully, I only need four and have five in case I screw one up.  I do need to rebuild them.   Do you sell a standard rebuild kit or is what is purchased custom per carb?  And do you sell the two pages in the Stromberg manual?

 

Mark

[carbking]

Mark - give me a call during normal telephone hours.

 

Jon.