[Updraft Stromberg SF-3 or 4 Carburetor wanted]

On 5/29/2018 at 9:22 AM, carbking said:

Alan - this link will explain the bore or "throat" size, and also the internal venturi sizes:

 

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

 

Note that some SF-4's do have accelerator pumps, others do not.

 

The numbers from your tag don't seem to show up in the Stromberg literature.

 

The best way to get a feeling for if a specific carburetor has or doesn't have an accelerator pump, is to look for the presence of the pump adjustment screw. Go back to the link, and scroll down to the pictured SF-4 carburetor. In the upper left corner of the picture is a long vertical 10x24 fillister headed screw. This screw is the pump adjustment screw. By varying the depth (adjustment) on this screw, one can vary the length of the pump stroke, thus saving gasoline?????

 

The carbs without an accelerator pump will not have the screw, rather just a short headless brass plug in the machined hole.

 

And the variable aspect, using your words, is in the internal venturi size. The physical size (SF-4) is the external size. The venturi size determines airflow. And the jetting is selected to correspond to the airflow.

 

Jon.

Jon, do you by chance have instruction on how to adjust that pump adjustment screw? Thanks

[Stearns Knight]

On 3/1/2021 at 6:27 PM, Mark66A said:

One more note. I have a very nice, rebuilt Stromberg SF3 which I have been hoping to bolt up to a Stearns Knight 8 cyl. However - it will not fit. It has a big butt and will not wiggle in between the cylinder block and the steering box. Sigh.... now I apparently have to find a Zenith63AW14. My supply of unusable nicely rebuilt vintage carbs is growing.

Looking for info on my SFM3, parts adjustments etc.

On 3/1/2021 at 6:27 PM, Mark66A said:

One more note. I have a very nice, rebuilt Stromberg SF3 which I have been hoping to bolt up to a Stearns Knight 8 cyl. However - it will not fit. It has a big butt and will not wiggle in between the cylinder block and the steering box. Sigh.... now I apparently have to find a Zenith63AW14. My supply of unusable nicely rebuilt vintage carbs is growing.

Hi There I'm looking for some help on my SFM3, parts and adjustments. Thanks