Installing fuel line

[tim52]

I just replaced my sediment filter/shutoff and am attempting to reinstall my metal fuel line in my ‘47 cub.

The threads are still OK on my carburetor but the fuel line remains loose when I tighten the brass fitting with an attached ferrule. I’m reluctant to tighten too much to wreck the carburetor threads.

What is the best approach for this?

Thanks!

[tim52]

Just thinking, maybe flare the line ends to snug the fit of the ferrule?

[Ruralguy57]

I have a `68 Cub Lo Boy. I have taken the tank/hood off the tractor and run with an aux tank while working on the tractor. In my case to actually do this, You must remove the fuel line from the carb first. Then when then tank and hood are unfastened then you unfasten the line from the fuel bowl. Once that is removed then you can take everything off. To put the tank and hood back on you have to squirrel in the fuel line before attaching anything as it fits between the exhaust and the body on my tractor and is bent to that shape. Attach the fuel line to the bottom of the sediment bowl first....try adjusting all bolts for the tank and hood. Then there is a nut and a set nut that you have to screw into place on the carb fuel line end. I have to have a small thin wrench to get the lock nut to take up as it is almost totally behind the oil fill cap/breather. One note, before you lock everything down, let the fuel bowl run a bit and make sure there is no fuel block or air lock or anything. Make sure both ends are snug tite. Do not over tighten. That is how I have to attach everything on my tractor. Currently I have the aux tank on and am running that with a barb from the sediment bowl on the small tank to a barb on the carb with flexi hose. However, when the tank and hood are painted, I will have to reassemble the entire thing as described here.

[Jim Becker]

. . . The threads are still OK on my carburetor but the fuel line remains loose when I tighten the brass fitting with an attached ferrule. I’m reluctant to tighten too much to wreck the carburetor threads. . . .

I recently had to deal with the same situation. I really didn't want to strip out the threads in the carburetor! After I couldn't get the ferrule to properly seal with a force I was comfortable with, I unscrewed the fitting from the carburetor then screwed it into separate brass fitting of the same style as the carburetor and snugged it down. I could then remove the fitting from the fuel line and assemble the fuel line to the carburetor. If you have everything else connected and this is your last step, you will find it necessary to undo the other end and move the fuel line to get room to screw it together with a separate fitting.

Restated, I used a separate fitting as a die to form the end of the ferrule and fuel line. I happened to have the appropriate fitting on hand. If you don't, it would probably be worth while to go buy one to avoid damaging the carburetor threads.

I'm unclear on what Ruralguy57 described, but it sounds like he has some non-standard hardware on his fuel line. Most hose barbs have tapered pipe threads on the opposite end and cannot be installed in a carburetor without damaging the original threads.

[Dale Finch]

I have done what Jim did. I thought perhaps, while tightening the nut, the ferrule was being push back too far, allowing the end of the tubing to bottom out before the ferrule seated.

[tim52]

I guess I did not describe things clearly.

With the fitting screwed tight, the fuel line is not gripped tightly enough by the ferrule, thus the fuel leakage.

On my original bent and rusty fuel line, not currently used, the ferrule is separated from the brass fitting and is tight near the end of fuel line. On my new fuel line with these newer fittings, does the ferrule portion break away? How does it grip?

[Bob McCarty]

When your new line is installed, the ferrule should crimp onto the line and separate from the fitting. What Jim is suggesting is that you do that with a brass female fitting separate from the carburetor to avoid harming the threads. Once the ferrule is crimped onto the line, you can install it on the carb. Also check the shoulder where the ferrule would seal and make sure it isn't severely corroded.

[Jim Becker]

Yes, what you said earlier was clear and I understood exactly what you were describing. What Bob said was exactly what I was trying to suggest.

[tim52]

Ok, got it thank you!

[Ruralguy57]

Aux tank 1

This picture shows the Aux tank. It is where I used a barb on the Sediment bowl. I used a second barb on the carb and a flexi line. This was designed to run the Cub Lo Boy while the hood is off to work on various things. I have documented the things I have worked on over the past months in a different thread. You can not check on the plugs with the hood on. You can not check on or change the oil easily with the hood on. The Aux tank allows me to also paint and sand the cast iron parts. I am in the process of working on the hood that needs to be repainted as well. In fact, I have mowed the property over the last 2 months, nearly 2 acres, with the aux tank. I have put gas in it and Lucas gas stabilizer which works on the cylinders etc., while mowing. With the small tank on, I have also pulled brush and more.


Richard

[Bob McCarty]

Ruralguy, As mentioned above, the sediment bowl and carb inlet threads are 1/2-20. The majority of fittings with a barbed hose fitting are 1/4" NPT, pipe thread. When you go to reinstall the steel line, you'll find that you've stripped the threads and will have to helicoil both inlets or use an alternate repair method. The better idea for pony tanks is to cut two 3-4" pieces of 5/16" brake line and add compression fittings on each piece. You can then slide rubber gas line onto the steel pipe pieces with hose clamps and not risk stripping the inlet threads.

[Bob McCarty]

Tim, Stop by a hardware store and pick up a 5/16" brass compression fitting. That can be used to crimp the ferrule outside of the carb.

[Ruralguy57]

Bob McCarty...

Actually a tool and die friend was super afraid of what you just said. So he actually has a barb with the correct threading for the carb. This came from his personal stock that came off e-bay. He also had the same fear of the sediment bowl being stripped. That barb threads match the sediment bowl threads. The threads were not stripped on either piece. In fact the original steel fuel line will work. We have tried it in the carb. We actually used a small funnel on the steel fuel line to start with 2 months ago, while figuring out how to design an aux tank. We were running the tractor and adding gas in the funnel. This was done to determine if the throttle shaft worked, after I heated it up because it was rusted solid; and to see exactly what the carb was doing. Once we got this ironed out, and the tractor was running with out the use of the choke, we designed the aux tank. After that I pulled the carb and blew it out with air with out taking the 2 halves apart. Once installed we continued testing the tractor. Having cleaned out the carb, the tractor seemed to run a lot smoother. But thank you for the concern. I did not want to damage the original IH carb. The tool and die guy is retired and has been in the business over 50 years. He is very careful about stripping or damaging parts.


Richard

[Bob McCarty]

Richard, That's good to hear. You don't know how many inlets have had to be helicoiled because a pipe thread fitting was used.

[Ruralguy57]

Bob,

I am very afraid to let anyone do anything to the Cub. However this Tool and Die guy is super anal about details and works hard to not damage anything. We went through a number of sizes before we got the right combination. I stood in his garage the one day when he wanted me to change the broke butterfly bleeder on the other side of the sediment bowl that had a non standard screw in it's place. He wanted me to use another bolt in it than what I am using. I am using a bolt with pipe tape that is overly long. However, it allows the fuel to flow in the sediment bowl. I am not changing something that actually works unless I have to. When we go back to the Hood and Gas tank, and no longer use the aux tank; I will change the bolt in the sediment bowl. In the other thread, I have been posting everything I have changed and updated and try to show photos and descriptions, as I go through this process; so others who have a Cub can see how to do what I have done.