WWII era Stromberg[?] aircraft float-type carburettor - can anyone help identify?

[Caroline]

Hiya,
I'm an archaeologist working on a range of military aircraft parts that were dumped in Darwin Harbour at the end of the war. So far we've found mostly PBY Catalina components, with a few Spitfire bits thrown in. Our most recent find is a two-barrel float-type carburettor that I'm having a world of trouble identifying - my aircraft carb knowledge is very thin and very unfortunately for me, this one has lost it's data plate [!].
It has an approximate 45 degree angle between the air intake and base, which made me think it might be one of the downdraft carbs that used to be mounted in the vee of Allison engines before superchargers were introduced - but no luck with that and I've now entirely hit a wall.
I've found a few numbers stamped into the body - including "NA - [?]12" and "564787" on the base flange, and "P60195" "7", "ECAE" "RWL" and "1 RBO" all on the main body. It's not in the best condition and some of the numbers are partially missing or very hard to read - so I could have read them wrong. But the "NA" and "P60195" are what are making me think it might be Stromberg.
I've attached a few pictures [the scale is 50 cm]. If anyone has any thoughts or suggestions on what type of carb it is and / or what type of aircraft it may be from, I would be immensely grateful!
Thank you,
Caroline.

 

[GregP]

Hi Caroline,

You might try asking Joe Yancey at Yancey Enterprises, Rialto, CA.

He is an Allison builder and has about 130 Allison ready for overhaul ... and ALL the parts plus many yeat=rs of accumulated knowledge in Allisons, Merlins, Griffons, and a host of radials.

Good luck.

 

[vikingBerserker]

Very cool Caroline and welcome aboard, good luck!

 

[Caroline]

Hi Greg,
Wow! Thank you very much - he sounds like the perfect person to get in touch with!
I''ll do that.
Thanks again

 

[Caroline]

Hi Viking Berserker,
Thank you for your welcome message. I might need luck - this carb is proving very stubborn to identify!
Thanks again

 

[GrauGeist]

Caroline, that certainly looks like a Bendix Stromberg used on a Pratt Whitney

Perhaps find a Pratt Whitney Installation Handbook and it should have the cross-references for the model types/applications.

I have a handbook somewhere for a Bendix NA-Y9E (used on the Wasp) and it's very close in appearance to your carb in the photos.

 

[Caroline]

Hi GrauGeist,
Thank you so much for your reply. I've been going round in circles with this and I am very glad indeed to hear you say you think it looks like a Bendix Stromberg from a Pratt Whitney! After reading your message I've just done a specific search on the NA-Y9E and found a parts illustration of one and it is definitely the closest I've seen so far. I'll see if I can find a P&W Installation Handbook and cross check - thank you very much for that suggestion - and fingers crossed....
Thanks again for all your help

 

[GrauGeist]

Glad I could be of some help, Caroline!

Best of luck and keep us informed on how the search is going!

 

[Caroline]

Thank you!! I will do

 

[MiTasol]

Veeeeery interesting

First you need to determine the venturi diameter and thus the carb venturi number. Obviously if it works out to be a smaller throat then that changes the carb part number and engine(s) it may have been fitted to and hence the aircraft
Fortunately it is very easy to determine if this is a "#12" carb by just measuring the venturi diameter.

Based on your data it looks like an NA-D12 to me - its almost certainly an updraft model and the float chamber is definitely behind the barrels so you are looking at probably a very early R-1820 engine or similar - DC2 maybe You will note from the reference below that NA-Dn type carbs became obsolete circa 1930 so that potentially rules out the DC2 and makes life even more interesting.

Stromberg used a simple identification scheme where a series of letters and numbers were assembled to identify and describe how a carburetor was constructed. The first two letters described the carburetor design, followed by a number that identified the size, and numbers and letters to identify specific design details and modifications.
The first (two) letter(s) comprise a Basic Design Code that places the Bendix Stromberg carburetor in a design category, where:
"A" – Pressure Injection Carburetors
"E" – Pressure Injection Carburetors
"NA" – Float-Type Carburetors
"P" – Pressure Injection Carburetors

Example: NA-R9G

Prefix- "NA" – for float-type carburetors followed by a "-"(dash)
The next letter indicates type, where
"S" – Single venturi updraft designed for two, three and four cylinder engines in the 25~95 hp class. NOT fitted with economizer, acceleration pump or mixture controls.
"R" – Single venturi updraft, designed for engines of all types in the 50-400 hp class. All are similar in design and incorporate needle valve type mixture control, accelerator pump and economizer. Some bodies are interchangeable in this series and deferent design economizers are used.
"D" – Double updraft venturi, with the float chamber to the rear, was considered obsolete c.1930
"U" – Double updraft venturi, with the float chamber between barrels.
"Y" – Double vertical venturi (updraft), with two float chambers fore/aft of barrels.
"L" – Inverted, down draft venturi.
"T" – Triple venturi, double float chamber fore/aft of barrels. The NA-T4 series is the only known model. Designed for use on Wright J-5 and
other 9-cylinder radials, where each venturi feeds three cylinders. It has float similar to Y series, but with back suction mixture control. No
economizer or accelerator pump.
"F" – Four-venturi with two separate float chambers.
The number following the type is the venturi diameter and 12 indicates a 3-1/8 venturi (2 indicates 1-1/8)
Subsequent letters are variations

My references only cover NA-?12s for Pratt engines and Pratt went to the PD series carbs in the mid 30s for new designs,
The Allisons used PD-12 carbs from the -7 on and all Allisons had flat not angled intakes
Here is the list I have of NA-?12 carb installations from a NASM document. Unfortunately it only shows Pratt and Packard installations

My other bible (USAAF Maintenance Interchangeability X ref charts TO 00-25-29 (1943-12)) does not show any NA-?12 carbs left in service at that stage, only the smaller carbs for Harvard and smaller aircraft