marvel carb number

[boeing]

Hi guys, i am starting a search to place a MS carb on my champ (C-85-8)
I am sure the info is somewhere, but i cannot seem to locate it.
What is the exact part # i need to fit my engine?
I know its a MA3SPA, and i am thinking that it may be a 10-4240-1.
If this is correct is this the ONLY one that will fit? or is there a range of different MA3SPA's that will also work?
I have seen a few Ma3's on E-bay, but the part number was different.
So that been said...Does anyone out there have one for sale or know of a good place to purchase one??
Have been having on going engine issues with the old Stromberg and its time to change.

[Carl Prather]

Hey Boeing,

What would you wnat for that leaky old Stromberg? As for ehich Stromberg to use, try this link:

http://www.2aps.com/CFS%20CarbAppl.pdf# ... arburetors'

I tink if you look at the parts list, there are only a few, but important, parts which make up the difference between the carburetor you speak of.

Carl

[Carl Prather]

Hey Boeing,

What would you wnat for that leaky old Stromberg? As for ehich Stromberg to use, try this link:

http://www.2aps.com/CFS%20CarbAppl.pdf# ... arburetors'

I think if you look at the parts list, there are only a few, but important, parts which make up the difference between the carburetor you speak of.

Carl

[boeing]

So what are the differences between all the part numbers, so lets say a 4894 which would fit on a 0-200,versus a 4240 that is matched up to a C-85. Is the body itself the same with different jetting or other internal parts?
The 3 listings on E-bay are a 10-2983, a 4115, and a 4894. They are all MA3SPA carbs, could i buy one of these and then have it rebuilt to 10-4240-1 specs?
I am having a hard time trying to find a place to buy.

[Mac]

I ran into the same problem as you did when I was looking for a carb for my o235. The first place I would check is the TC for the engine, it should have the different carbs listed, also look at an engine parts manual. In the Lycoming manual they tell what carbs can go on the engine, I don't know if Continental will do the same. I had to buy an old carb core and had it rebuilt to a new specification, they just replaced the jets etc.
Good luck.

Scott

[Carl Prather]

Boeing,

The differences can be important, so any changes to the carb should be made to match the intended use. I think the float levels and oirfices and needle sizes are different. This is from memory and I have never done this so you would have to look into it closely. I have looked at the parts lists and many the carbs are exaclty the same except for 2 maybe 3 parts.
I have been told by some mechanics that if the Type Certificate does not specify the carburetor beyond MA3-SPA (no part number), he feels there is no reason not to take another part number and rebuild with the more appropriate parts and set the the correct and THEN RECORD THIS IN THE LOGBOOK AND TAG THE CARB. This way someone won't try to fly a 145 horse Cessna 170 on a carb set up for a 85 horse Champ and you are not trying to conceal what work was done. Anyway, the folks I spoke with say the only difference between the carbs is stamping on the date plate. If you do this, be certain that what I say is 100% correct. It would be bad something like a cast aluminum float bowl carries a different part number from Marvel carb to another.

[boeing]

I still have not decided if i am going to rebuild the Stromberg or keep trying to track down a MS carb. Up until about 5 days ago i was one of those guys who had no complaints with the stromberg carb. I started to have partial power loss issues at take off rpm and we have tracked it to a neoprene needle swelling issue. (we think).
It would definitely be much cheaper and simpler to just overhaul the Stromberg, but i would also like to have a mixture control as our field here is 3500 asl and its been HOT! ( do the math on the density). Also getting rid of the leaky carb issue would be nice. That been said i was one of the lucky ones and my Stromberg never leaked (much).
So the million dollar question is
" why would it be so bad to replace the valve with another neoprene one?"
Far as i can tell its been over 15 years since the carb has been apart,
and even then i don't know if they replaced the valve and seat. It seems to me after all the reading i have done, that the neoprene seals the best, but has issues when using inconsistent fuel grades, or mo-gas. If i could quite simply replace the valve with another neoprene one, and not have to attempt to seat a stainless or delrin type, i would be willing to risk getting another 10 plus years with a neoprene needle.
a little while back someone posted a thread on how to lap a valve and seat, does anyone know where i can find info on that? Also any info on where to get needles and seats (other than Spruce) or a lead on a Marvel carb would sure be appreciated.

[Mnflyer]

Hi Boeing, there is a mixture control available for the Stomberg carbs, it work s but is a bit touchy and are ineffective below 2500 feet.
The Stromberg is a good carb if properly overhauled and set up.

[Paul Agaliotis]

I think Fresno Airparts still has the parts. The steel needle works the best when properly seated.
The little Continentals dont like to be operated very lean. It tends to cause exhaust valves to stretch and ring / cylinder distress.
Paul