tcslr Posted June 23, 2022 Share Posted June 23, 2022 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 Link to comment Share on other sites More sharing options...
Rock10 Posted June 23, 2022 Share Posted June 23, 2022 Pictures? Link to comment Share on other sites More sharing options...
tcslr Posted June 23, 2022 Author Share Posted June 23, 2022 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. Link to comment Share on other sites More sharing options...
tcslr Posted June 23, 2022 Author Share Posted June 23, 2022 sorry. dragging and dropping did not appear to be successful Link to comment Share on other sites More sharing options...
Rock10 Posted June 23, 2022 Share Posted June 23, 2022 Sorry, I meant pictures of the pump, not the number. Link to comment Share on other sites More sharing options...
Rock10 Posted June 23, 2022 Share Posted June 23, 2022 Link to comment Share on other sites More sharing options...
Dave39MD Posted June 23, 2022 Share Posted June 23, 2022 (edited) 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 Edited June 23, 2022 by Dave39MD (see edit history) 2 Link to comment Share on other sites More sharing options...
Dave39MD Posted June 23, 2022 Share Posted June 23, 2022 I believe this is what it looks like; 1 Link to comment Share on other sites More sharing options...
Bloo Posted June 23, 2022 Share Posted June 23, 2022 (edited) 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 June 23, 2022 by Bloo (see edit history) Link to comment Share on other sites More sharing options...
Dave39MD Posted June 23, 2022 Share Posted June 23, 2022 I have some old books, this one is the best for the prewar AC pumps. Let me know if you need anything from it. Dave 3 Link to comment Share on other sites More sharing options...
tcslr Posted June 23, 2022 Author Share Posted June 23, 2022 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 Link to comment Share on other sites More sharing options...
Dave39MD Posted June 23, 2022 Share Posted June 23, 2022 Tom, What info do you need? Link to comment Share on other sites More sharing options...
tcslr Posted June 24, 2022 Author Share Posted June 24, 2022 Replacement parts. Substitutions and technical data - especially flows, pressures, etc. TIA, Tom Link to comment Share on other sites More sharing options...
Dave39MD Posted June 24, 2022 Share Posted June 24, 2022 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 Link to comment Share on other sites More sharing options...
32buick67 Posted June 24, 2022 Share Posted June 24, 2022 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. Your bottom cover 855228 is used on many pumps: Interesting that AC also had top-level assembly 856139 listed for the 31-90, in addition to the 855751: 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. Link to comment Share on other sites More sharing options...
Dave39MD Posted June 24, 2022 Share Posted June 24, 2022 The 6139 is listed as a heavy duty pump. Dave 1 Link to comment Share on other sites More sharing options...
tcslr Posted June 24, 2022 Author Share Posted June 24, 2022 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) 1 Link to comment Share on other sites More sharing options...
Dave39MD Posted June 24, 2022 Share Posted June 24, 2022 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 1 Link to comment Share on other sites More sharing options...
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