Marvel Schebler (Bendix) carb, self-overhaul

[Robert Lees]

I'm taking apart a spare C-85 M-S carb to overhaul.


My carb is a NA-S3A1, Continental P/No 40590, and the number stamped is 380167-2. This is for a C85. I have the 1971 manuals (lots of them), and I think I understand that the "new" dash number is -4 (reflecting an update to a part number, rather than any change the carb itself.

I'm happy with the usual overhaul stuff...setting float levels, needle & seat differences, etc, ...but I do have a few questions for those more knowledgable than me:

1. Is the rubber-tipped needle P/No 390077 still legal in the US?

2. My 1971 Bendix manuals seem to suggest two different carbs for the C-85-12 (Part numbers 380167-4 and 380172-2)...why the difference?

3. They specify the C85-12...why not the C85-8?

4. Can a C-85 carb be used on a C90?

I consider myself fairly capable, but the plethora of part numbers, issue numbers & so on, take some getting used to (plus of course the SB's.). Simple stuff when you know, I'm sure, and I'm keen to learn.

It's an excercise of course, none of my efforts will be fitted to a certified aircraft, but I'd like to do it right.

Thanks for any input,
Regards
Rob

[baldeagle27]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Rob, can't answer all your questions, but the Marvel Schebler and Bendix (Stromberg) are two different carbs, the NAS3A1 is Bendix. I don't know about legality, but I think people don't use the rubber tipped needle any more because there was concern that if any alcohol got in the fuel it would swell the rubber and lean out the mixture. I'm sure that somebody more knowlegeable will fill in the blanks-

Edit: found this: http://www.bowersflybaby.com/tech/st...20needles1.pdf apparently from 2005



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[Obelix]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Hi Rob

Attached is some info on the Marvel Shebler, yours is then probably a Bendix, as I cannot find the part no's you mention.

I couldn't get a carb for my O-200, eventually found one coming off a O-300. Only had to change the main jet and Venturi and it was same as required for the O-200. So possibly yours could work for the C90 or maybe you just need to change a few internals.

[cvavon]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Robert there were 3 different needles with the impending changes with gas coming i think i would stay with the stainless steel one now they do seep when the fuel is left on so shut the main fuel valve off when parked and they can be lapped in and help this. the two different numbers i think are for with mixture and without there is also a carb that had a b in the part number and it was without mixture also lots of imfo on the net under stromberg carb

[Robert Lees]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Yes, apologies, it's a Bendix NA-S3A1 carb.

Thanks for the input so far.

[dmcneil]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Rob,


1. The Neoprene tipped needle is not illegal (no AD) but they are not commonly seen much anymore. New ones haven't been made in many years and the chance of swelling when using car gas have caused most to be changed. One other point... the seat for the Neoprene needle has rounded shoulders where the needle seats. The seat for the steel needle has sharp edges that are straight bevels. The seats are not interchangeable. The rounded seat is also used with the Delrin needle.

2. p.n. 380172-2 is for the C-85 using a fuel pump at 2-4 psi
p.n. 380167-4 is for the C-85 using gravity feed at 1/2 psi

These two carbs have different build sheets. I haven't looked at them closely enough to note all the differences but there are differences. Most folks don't realize that these carbs have so many different part numbers and corresponding build sheets. Because they've been around so long, there's no telling what bits you'll find when you open one up.

3. Don't know why the C-85-8 is not specified. The older parts lists and build sheets just called out "C-85" and didn't differentiate between -12 and -8. There were only two part numbers in those earlier parts lists... one for gravity feed and one for fuel pump pressure feed.

4. A C-85 carb will probably work on a C-90 but it's not the correct carb for the C-90. Again, lots of different bits in the C-85 vs. C-90 carbs. Additionally, there are 5 or 6 different build sheets for various C-90 applications (-12, -14, fuel pump or gravity feed, etc.)

It's really important to have all the manuals and build sheets on these carbs. It takes some time to sort through everything but eventually it will make some sense. There are just too many variations to keep track of...

Dan

[Craig]

Re: Marvel Schebler (Bendix) carb, self-overhaul

Do you belong to the Taylorcraft Owners club? There last newsletter had a great article concerning the NA-S3 Carbs.
If not let me know and I'll post there address, phone, etc

Craig