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  #1  
Old 11-18-2018, 02:01 PM
pstraub's Avatar
pstraub pstraub is offline
 
Join Date: Nov 2015
Location: Galt, CA
Posts: 116
Default New member of the 'Sinker Club' (carb floats)

After about 125 hours on my RV-12, I was beginning to think I would be one of the lucky few without carb float problems....I was wrong! Doing my night currency last week, I noticed the smell of fuel in my cabin for the first time. Also, my idle had been gradually getting rougher. After shutting down for the night, I opened the oil tank door on the top cowl and the fuel smell was very strong. With a flashlight, I could see standing fuel in the drip tray! I removed the top cowl and dropped the float bowl.....sure enough, the floats were mostly submerged. After letting them dry, I weighed the pair and they were 11.4 grams. I then checked the left carb floats, they were not as bad yet, but still over weight at 9.5 grams. I just ordered 2 pair of the latest PN, 861188. Wow, $300!! I guess I have a new and expensive 'consumable', this engine is 1.5 years old with 125 hours. Based on everything I have read, I am not confident that the new floats will last any longer. Maybe it's the ethanol in this California fuel. I just wanted to add my experience as a data point.



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Paul Straub, First Flight May 5, 2017
N917PB, SN 120971
120 hours and counting.....
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  #2  
Old 11-18-2018, 02:47 PM
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Piper J3 Piper J3 is offline
 
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Location: Hinckley, Ohio
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Paul

Can you take quality photos to show all sides of a single float? Maybe lay a metric scale next to the float so size can be inferred. I want to see if I can get an injection mold company to prototype a hollow plastic float with brass actuating pin and brass guide tube as integral part of the design. Maybe we can make our own floats that would be hollow and float like a fishing bobber.

Maybe wishful thinking, but I will spend some time contacting injection mold people if I can get a decent set of photos of the existing Bing float. I'm even thinking about possibility of 3D printing.

Lots of companies do prototyping and small production runs.

A quick search found this company...
https://www.xometry.com/injection-mo...RoCC2MQAvD_BwE
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Jim Stricker
Hinckley, Ohio (1OA2)
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
RV-12 E-LSA #120058 AWC July 2012 N633CM
RV-12 Bought Flying Oct 2015 with 48TT - Hobbs now 425

LSRM-A Certificate 2016
Special Thanks... EJ Trucks - Crew Chief A-4 Skyhawk
and MJ Stricker (Flight Instructor) - 1st Lt./Captain B-17H
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  #3  
Old 11-18-2018, 03:13 PM
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snopercod snopercod is offline
 
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Location: Asheville, NC
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Other than the rough idle, were there any other symptoms - excessive mag drop on runup, perhaps? The reason I ask is that my RV-12 buddy has been fighting that and his front spark plugs keep getting carboned up. He just had his carbs "adjusted".
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  #4  
Old 11-18-2018, 03:35 PM
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pstraub pstraub is offline
 
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Location: Galt, CA
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Default

Quote:
Originally Posted by Piper J3 View Post
Paul

Can you take quality photos to show all sides of a single float?
Hi Jim, I would be happy to send you a pair of these, I won't use them again. You idea sounds like a worthwhile effort!

Quote:
Originally Posted by snopercod View Post
Other than the rough idle, were there any other symptoms - excessive mag drop on runup, perhaps? The reason I ask is that my RV-12 buddy has been fighting that and his front spark plugs keep getting carboned up. He just had his carbs "adjusted".
The only other symptom I had was the obvious smell of fuel in the cabin, and very strong in the engine bay. I would assume my plugs don't look great right now, since it would be running so rich at idle, but I have not pulled them. Everything seemed great for my first 120 hours, I guess the floats just slowly absorb fuel until they are just too heavy. My left carb (floats weighed 9.5g) was not dumping fuel into the drip tray yet, at least not noticeably, but I am sure it was just a matter of time. The right side had standing fuel in the drip tray, so that additional 2g seemed to make a big difference in the bouyancy of the floats.
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N917PB, SN 120971
120 hours and counting.....
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  #5  
Old 11-18-2018, 04:08 PM
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Piper J3 Piper J3 is offline
 
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Paul - I'll send you PM/email with my shipping address.

I've already contacted a friend who is a premier machine designer and he will draw the part. Also contacted a friend with high quality 3D printer to ask his opinion.

Maybe hollow float could be made with rotational mold process using same red plastic as used for approved gasoline storage cans. The two piece-mold could have ability to hold pre-cut brass tube in correct location in each mold half and also brass actuating pin on the mold parting line. When mold opens and part is removed the access brass tubing length would be hand-trimmed.

Fun thinking about this stuff. I've been retired five years but this is right up my alley...

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Jim Stricker
Hinckley, Ohio (1OA2)
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
RV-12 E-LSA #120058 AWC July 2012 N633CM
RV-12 Bought Flying Oct 2015 with 48TT - Hobbs now 425

LSRM-A Certificate 2016
Special Thanks... EJ Trucks - Crew Chief A-4 Skyhawk
and MJ Stricker (Flight Instructor) - 1st Lt./Captain B-17H
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  #6  
Old 11-18-2018, 05:16 PM
mcems mcems is offline
 
Join Date: Apr 2008
Location: Salem SD
Posts: 149
Default

I guess I got to feel sorry for all the guys having float issues. The cost of replacing is insane. Only to find out the replacements fail too.

I have to tell you that I have my original floats that came with my RV 12 kit that I finished and flew in 2009. I now have 1000 hours on them. I weighted them yesterday . They all came in under 3 g . 2 where at 2.98 and 2 where at 2.99.

I have never had a problem with them. The same floats are used in the Rotax 503 Bing 54 and 23 years of flying with those I never had a heavy float .

Some where something changed and in my experience I don't believe it was 10% ethanol.

Must have been a change in the way they where made or what they where material they where made of.

Brad Stiefvater
124 BJ first customer built RV 12 to be airwothied and fly
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  #7  
Old 11-18-2018, 05:55 PM
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Piper J3 Piper J3 is offline
 
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Quote:
Originally Posted by mcems View Post
I have to tell you that I have my original floats that came with my RV 12 kit that I finished and flew in 2009. I now have 1000 hours on them. I weighted them yesterday . They all came in under 3 g . 2 where at 2.98 and 2 where at 2.99.

Do you run Avgas or auto fuel? With 10% alcohol?
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Jim Stricker
Hinckley, Ohio (1OA2)
EAA #499867
PPL/ASEL 1970 - Sport Pilot since 2007
80 hrs Flying Aeronca Chief 11AC N86203
1130 hrs Flying 46 Piper J-3 Cub N6841H
RV-12 E-LSA #120058 AWC July 2012 N633CM
RV-12 Bought Flying Oct 2015 with 48TT - Hobbs now 425

LSRM-A Certificate 2016
Special Thanks... EJ Trucks - Crew Chief A-4 Skyhawk
and MJ Stricker (Flight Instructor) - 1st Lt./Captain B-17H
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  #8  
Old 11-18-2018, 06:12 PM
mcems mcems is offline
 
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Location: Salem SD
Posts: 149
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I use auto premium with no ethanol 90% of the time in the 12 .But I did use 10% ethanol in the 503 for years .Same floats.


Brad
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  #9  
Old 11-18-2018, 10:30 PM
PMLviator PMLviator is offline
 
Join Date: Mar 2014
Location: Groveland CA
Posts: 42
Default MS floats

Paul, will you be looking into the Marvel Schebler MS80-430 solid epoxy floats that there has been much discussion here on VAF as an alternate?
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  #10  
Old 11-19-2018, 12:14 AM
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pstraub pstraub is offline
 
Join Date: Nov 2015
Location: Galt, CA
Posts: 116
Default

Quote:
Originally Posted by mcems View Post
I have to tell you that I have my original floats that came with my RV 12 kit that I finished and flew in 2009. I now have 1000 hours on them. I weighted them yesterday . They all came in under 3 g . 2 where at 2.98 and 2 where at 2.99.
Wow Brad, 1000 hours on your original floats and they still weigh under 3g each!! They should be sent to the Bing Hall of Fame!!

Quote:
Originally Posted by PMLviator View Post
Paul, will you be looking into the Marvel Schebler MS80-430 solid epoxy floats that there has been much discussion here on VAF as an alternate?
I wanted to order the MS floats, then read the post from 'n233va' from a few weeks ago. He had a major issue with them, he said they have a smaller hole, and don't have the internal brass sleeve so they would hang up on the posts. So I just decided to try the latest PN of the Rotax (Bing) floats and see what happens. I am hoping we get more data about the MS floats.
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N917PB, SN 120971
120 hours and counting.....
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