#1
IP: 207.55.29.114
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Technicial Question on fuel system tubing
All,
I have a question on the reliability of the two types of copper tube fittings? These are the flair and compression joins. I am in the process of familiarizing my self with the Zenith 86 carburetor. I was able to find the back ground information on the scavenge tube on the list. Part of my process is to build a emergency parts kit so that should I have to make repairs the need parts could be are on board. The scavenge tube is a uncommon item as it is a 1/8th inch tube. I was able to find that dimension of tube and brass fittings. What I have not found is a 1/8th flare vice and tool. My old vice's smallest dimension is 5/16th. Checking with some of the better hardware stores in the area I was unable to locate the needed tools. I have greater trust in the flare joint system. It appears that I could assemble the scavenge tube with compression fittings. Does any one a an opinion or knowledge on which joint is the most reliable? Yes, I could buy the part from Moyer Marine. The effort here is take responsibility for my boat's performance and reliability and to learn how to make repairs and under take maintenance. Any thoughts on this is most welcome. Thank you, Mart |
#2
IP: 76.189.1.205
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I believe gas line fittings are REQUIRED to be flare fittings and compression fittings are not permitted. I don't know if the scavenger tube would count as a gas line, since it's not pressurized at all, but a leak would be bad, and this is one place where I'd buy the part to do it right rather than take a chance.
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Mark Smith 1977 c&c30 Mk1 hailing from Port Clinton, Ohio |
#3
IP: 173.11.96.181
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When I rebuilt my engine and was re-installing the scavenge tube, I could not find flared fittings in the tiny 1/8" size, but I did find compression fittings. I have not had a problem yet. Lots of plumbing jobs use compression fittings (every supply line under your sink or toilet, as well as your refrigerator's icemaker supply line). As long as it's done correctly (a rule that applies equally to a flared fitting), I don't see why it should be a concern.
Someone will be along shortly to correct me if I'm totally mistaken here.
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- Bill T. - Richmond, VA Relentless pursuer of lost causes |
#4
IP: 184.0.176.66
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This may be a question for Neil's CFR library.
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#5
IP: 24.152.131.155
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I dug through the CFR's on fuel systems. There's a discussion of scavenge tube requirement for updraft carburetors but nothing specific on the required material. It's therefore reasonable to apply the general requirements for tank to engine fuel line requirements to the scavenge tube because it handles fuel.
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others Last edited by ndutton; 04-20-2012 at 08:57 AM. |
#6
IP: 76.122.168.101
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Good News and Bad News
First the disclaimer: I used compression fittings in my motor rebuild.
However: 1/8" flair tools are pretty easy to find from industrial supply places like McMaster-Carr McMasterCarr Flair tool catalog page BUT they are not cheap--something over $100 for the cheapest. If you call around to some specialty plumbing, machine shops or the like you might be able to find someone to flair your tube for cheap. On the other hand, by time you pay for your gas and consider your travel time it might not cost anymore to include it with your next Moyer Marine order. |
#7
IP: 207.55.29.114
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All,
Very informative discussion. As a result, I have two additional questions. The first regards the material of the fuel line. Clearly, the fuel lines are required to be copper or Monel or copper-nickle if they are composed of metal. Given the occurrence of SAE fuel hose am I safe to assume that is considered safe and legal? The second question, CFR am I correct that this is a Coast Guard safety code published in the Consolidated Federal Register? |
#8
IP: 24.152.131.155
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Yes, it's the USCG standard. No, not the Consolidated Federal Register but close, it's the Code of Federal Regulations. For our purposes here I keep them close at hand. The articles regarding inboard gasoline engines, fuel systems, ventilation, exhaust systems and electrical seem to me to be a good reference and often times bring us back on track. Despite the wealth of experience on this forum, sometimes what is presented is contrary to the regs. For example, exhaust hot section material is frequently discussed, usually after a picture of a new galvanized system is posted. It will go back and forth with one member thinking this, another that and then we'll quote the USCG Regulation (actually the ABYC recommendation adopted into regulation by the Coasties). That usually settles the issue until the next time.
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Neil 1977 Catalina 30 San Pedro, California prior boats 1987 Westsail 32, 1970 Catalina 22 Had my hands in a few others |
#9
IP: 193.253.220.149
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next time
...and there is always a next time!
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Kelly 1964 Cheoy Lee Bermuda Ketch, Wind and Atomic powered |
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