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  #1  
Old 07-02-2022, 05:27 AM
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Inhot Inhot is offline
 
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Smile Avstar vs Marvel Schebler

Well, the 33 year old Facet carburetor in my RV6 (O-320 D1A) needs replacement/overhaul. My local A&P is a big fan of Avstar (both their new carbs and their overhauls of marvel scheblers). I can't find any reviews for their products and services. Anyone have any experience with Avstar? Comments about the overhauled Marvel Scheblers sold by Spruce? Any recommendations? Inquiring minds want to know.��
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  #2  
Old 07-02-2022, 07:01 AM
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Ed_Wischmeyer Ed_Wischmeyer is offline
 
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Default

I went straight to MarvelSchebler for a replacement carb because I had a non-stock request -- I wanted a carb that ran rich for summertime cooling, and the factory did that and, on the flow bench, adjusted it at the full rich end of the scale. Summer cooling problem solved (high EGT, not just high CHT)!

Spruce could not provide that level of customization, no surprise, and I learned a bunch by talking to the factory guys.

I'd advise you to talk to the factory. I learned a whole bunch...
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  #3  
Old 07-02-2022, 07:18 AM
Avengerboss Avengerboss is offline
 
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Default Type carb

Agreed
I just went thru an ordeal with a O320 , stock carbs donít work well with RVs , they need resetting at the factory then they work great.
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  #4  
Old 07-02-2022, 07:40 AM
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Carl Froehlich Carl Froehlich is offline
 
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Another option is to use this as opportunity to install the nice AirFlow Performance injection system.

On my first RV I got a O-360 engine from Vanís, but that was before they sold injected 180hp 360 engines. I never took the carb out of the box, just sold it. I installed the AirFlow Performance injection system and it has been flying perfectly over the last 20 years.

Carl
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  #5  
Old 07-02-2022, 08:38 AM
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Walt Walt is offline
 
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Recently replaced a carb on customers aircraft, rebuilt sourced from McFarlane direct from Marvel, looked like a brand-new unit and functioned perfectly out of the box.
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  #6  
Old 07-02-2022, 07:43 PM
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Default AVSTAR - Lycoming

Apparently Avstar now provides carburetors for Lycoming. I don't know if they've replaced Marvel Schebler altogether. Anybody out there flying with an Avstar Carb?
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Last edited by Inhot : 07-03-2022 at 09:50 AM.
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  #7  
Old 07-03-2022, 06:34 PM
rvsxer rvsxer is offline
 
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Location: Inver Grove Hgts, MN
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I replaced my MA4-5 p/n 10-1478-1 (O-360) with an Avstar rebuilt about 350 hours ago and it works fine. I actually wanted a genuine Marvel rebuilt but ordered this one accidentally. Marvel Schebler introduced a composite ("Smurf") blue float years ago and I put one in the last carb. It is a huge improvement over the metal floats. I called Avstar and they said they use their own metal float and that it won't fail either. So far, so good...

As for new carbs, we put a new Avstar carb on a Cardinal where I work and the whole thing was machined, not cast. A real work of art. How good it works, well, we'll see.

A new 10-3878-1 carb from M-S looks to be about $3,100. Of course, rebuilt or overhauled carbs are a lot less. An Airflow Performance fuel injection kit is about $3,700 (plus high pressure pump/filter assy). If you wanted a new carb, a conversion to FI might make sense. These prices are for 180 Lycomings, the 160 (MA4-SPA I think) might be lower.

I'm sorry if I just complicated things for you but I hope the info helps...
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Last edited by rvsxer : 07-03-2022 at 06:37 PM.
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  #8  
Old 07-04-2022, 05:24 AM
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Default Injection

Thanks for relating your experience. Going fuel injection would be nice, but it's just not in the budget. Purchasing a new MA-4SPA (Av10-5217) for my o320 will cost $1200 (with the core). Their carbs do look like works of art compared to the MS carbs.
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Last edited by Inhot : 07-04-2022 at 06:03 AM.
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  #9  
Old 07-04-2022, 05:20 PM
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Malndi Malndi is offline
 
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I replaced the ageing Precision 10-5217 on my O320-D1A with an AV10-5217. The new carby runs well but the fuel flow in climb is down quite a bit and CHTs are up a bit. I’m not the builder but I’m guessing the old carby had been re-jetted or drilled out - it was exchanged so I can’t check.

Enquired with Avstar about options for getting more fuel flow and they didn’t want to discuss it, they simply referred to the bench test records for my unit and said it is within spec. No doubt that would be true if it was installed on a Cessna.

I’m loath to modify the new carby experimentally and would prefer to implement a proven modification, but I’m not sure that exists. My reading on the subject turned up a lot of inconsistent advice. So it would be nice if this thread reveals sound advice on a replacement jet or drill size that better matches this carby to an RV.

For now, I would say that despite the AV10-5217 being the specified model for the O320-D1A, that’s probably not true for an RV given what I have read about our inductions.

Last edited by Malndi : 07-04-2022 at 05:24 PM.
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  #10  
Old 07-05-2022, 06:05 AM
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Default Enlightening

Malndi,
Thanks for sharing your experience. Your post jogged my memory about something I had read a while ago about carb modifications.

I searched the forum and came across this thread: https://vansairforce.net/community/s...r+modification

Apparently running lean with stock carbs is an issue for RVs. Maybe that Thread will get you moving in the right direction. I'll be sharing that thread with my A&P.

Thanks again for your post.
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