7040255 carb
October 2nd, 2017, 10:37 AM
#4
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Location: Brazil Indiana
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Just curious, What is the casting number on the base plate? It is located on the back right corner looking down at the bolt hole location. (right side looking at it from the front) Would be left side of car... It is in a circle
October 2nd, 2017, 10:45 AM
#5
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October 3rd, 2017, 01:45 AM
#10
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I looked at my old 7040255 W31 carb with a 0970 build date and it also has "N" hangers. The second one I had with similar early 70 build date (0900) had an "H" hangers. The 0900 carb was all original and taken off an auto W31. Hmmmmm
October 3rd, 2017, 04:38 AM
#11
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carb
Both 256's I have use the "G" hanger. I have an nos 256 as well, but don't want to remove the shrink/plastic top just to check the hanger. It's a service date with the later airhorn, so I'm guessing it's different.
Last edited by Vader; October 3rd, 2017 at 04:42 AM.
October 3rd, 2017, 06:19 AM
#12
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Thanks Dave, I didn't notice that. I do have a proper hanger, and it has the AU rods. Although Ive seen a few with AX rods as well. Get that fixed asap.
Both 256's I have use the "G" hanger. I have an nos 256 as well, but don't want to remove the shrink/plastic top just to check the hanger. It's a service date with the later airhorn, so I'm guessing it's different.
Both 256's I have use the "G" hanger. I have an nos 256 as well, but don't want to remove the shrink/plastic top just to check the hanger. It's a service date with the later airhorn, so I'm guessing it's different.
October 3rd, 2017, 10:30 AM
#13
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255
I changed the hanger to an E , and the rods are AU.
I heard that the hangers may have been changed anytime the carbs were flow tested or "trended" for the best performance. Any hanger which improved performance was used for that particular trend.
Eric, yes I had two other originals with an I, ad a J.
I heard that the hangers may have been changed anytime the carbs were flow tested or "trended" for the best performance. Any hanger which improved performance was used for that particular trend.
Eric, yes I had two other originals with an I, ad a J.
Last edited by Vader; October 3rd, 2017 at 10:40 AM.
October 3rd, 2017, 08:29 PM
#17
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OK, I checked my Rochester Engineering Secondary Air Valve Hanger Specifications Chart for Q-jets. I had made a hand written note next to the "E" hanger specs. which was "W31 #1", then next to "G, H, I hanger W31 #2". I agree on Rochester's Test Flow of all Q-jets and that they did make changes for both air/fuel flow and Emissions. Don't forget about the more strict Fed. Emissions for the 1970 Model Year Production that took effect on Jan 1st, 1970.
I just don't agree about the "N" hanger on a W31 carb. Maybe on a reg. 350 or 455. Also, on those 1970 W cars sold in Calif. that had to have the "N9" Emission Option may have had the "N" hanger. I never really got in to all the parts that made up the "N9" Option or the specs. I do know about certain aspects of the system, but not all, so I am pretty lame on that.
I just don't agree about the "N" hanger on a W31 carb. Maybe on a reg. 350 or 455. Also, on those 1970 W cars sold in Calif. that had to have the "N9" Emission Option may have had the "N" hanger. I never really got in to all the parts that made up the "N9" Option or the specs. I do know about certain aspects of the system, but not all, so I am pretty lame on that.
Last edited by davebw31; October 3rd, 2017 at 08:35 PM.
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