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help IDing fuel pump


tcslr
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I took an etching off the fuel pump on the  Buick 1931 90 series.  the pump has AC embossed.  Model 'B' but the number is 855228 ( maybe 3) but sure looks like an 8.  The reference material I have for 1931 90 series doesnot show that number on the body - can anyone tell me:

1) is this pump correct?

2) what IS the right number for the car?

3) obviously this seems to work - albeit - not good ( a whole different issue) - what was this body initially for? i.e.1935 blah blah blah

4) is it COMPATIBLE for this car?

 

Tom

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Pictures.  Be aware that these are reversed due to camera angle.  I have not yet removed the pump - yet.  The etching was using Al foil and lightly burnishing the embossment.  The number really looks like '855228'.  3861 is using an inspection mirror and zooming in.  3850 is a shot from underneath looking up.

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2 hours ago, Dave39MD said:

The bottom cover 855228 fits all of the the B series AC pumps which would include among others 29-33 Chevrolet. The body number for the 31 Buick pump 855751 should be 855785, rocker arm 1521745, and top cover 1523358.

 

Dave

 

Where do you find information like that?

 

Edited by Bloo (see edit history)
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Dave,  Can you send information on the 1931 90 series pumps?  I think the early Buick had a 'B' model that replaced by the 'D' model.

Appreciate the information - I learn something new every day.

Tom

 

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That book will only have old AC numbers and not any of the other information. If I were you I would try these guys at; then-now-auto.com

 

My 31 has a fuel pump someone built for it with a hand primer, it is useful but I looked around for the original. Then and Now offered to build me one from their parts but I found the one pictured above. I will take a few photos of the 31 Buick parts of the catalog and post them soon if that would help but the main numbers are above.

 

Dave

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Tom,

The stamping numbers on the piece-parts of the pumps are quite interchangeable, but the overall assembly is often exclusive to a small subset of vehicles.

Your 31-90 is common between 31-60/80/90 only, #855751 (and maybe 856139).

The top-level assembly part number is stamped in part, or in entirety, on the engine mounting flange or on the rim of the engine mounting flange.

 

image.png.821e4646e04d9321d3c58563e7642094.png

image.png.b438af3b4009784ddecd8c1af616b895.png

image.png.a7eed3b57e84899a915456f695e87af7.png

 

Your bottom cover 855228 is used on many pumps:

image.png.aae8dbed984d172b172fdb0d596ccd63.png

 

Interesting that AC also had top-level assembly 856139 listed for the 31-90, in addition to the 855751:

image.png.25ee743652a1e7f54e4a4f3fbc87b1b4.png

 

855751 has a different diaphragm part number than 856139, but 855751 might just be an earlier version and of no consequence.

 

Maybe Dave's AC book has more info.

My info is from books dating 1936 and 1951.

 

 

 

 

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According to Tom at 'then-and-now', the pump on the car (855228, model B ) is Chevrolet - and Mario's data says as much.  While the model B pumps initially came on the early 31s ( and mine is early),it was soon found that the output was inadequate over the range and especially on acceleration, top end, hot conditions, etc. (Tom mentioned that visibly, the two models looked very close- almost identical with the difference the number of screws ( slightly larger diameter head) holding the halves together - B=8 screws, D=10screws ( around the diameter).  I have one coming from them ( D model) and when I receive, I'll photograph this and share.)

Per Tom, Buick changed to the D model and that was the improvement - so that is the direction I am heading. 

 

Dave, the technical spec data is interesting ( if available) to compare the two.  That is what I'm hoping for.

 

This raises the next question - the carburetor.  The early carb was a 10-796 and later 31s was 10-984.  I need to examine the jets - but think that MAY have changed also ( jet sizes)

 

 

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Yes they are the fuel pump guys. The 6139 listed as the heavy duty pump in my catalog is a D series. Sounds like you are making progress. These pumps are pretty obscure so I probably won't have any performance info but it will give me an excuse to be in the cool basement while looking!

 

Dave 

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