Fuel line material and filter question

Thu Nov 21, 2013 7:44 pm

I have just received my carb back from being rebuilt by the good hands of one of our members ( Nice Job Sir! ). My plan is to have the tank completely cleaned out, sediment bowl gasket replaced, and install a new fuel line. I want be make sure everything is either new, rebuilt, super clean, and no gas leaks.

My question is:
#1Hose. Why don't Cubbers use modern "rubber" ( or insert other plastic chemical name here ) hose? Is it a looks/original equipment issue? I hear that copper will work harden and crack after some time in use? Is that the case with the Cub? How do you feel about braided SST/rubber? Is vapor lock/percolation an issue during hot weather? Wondering why I should stick with steel.

#2 in line filter. I seem to recall that somebody tried to use a lawnmower in-line disposable filter on their Cub. The response was that it would restrict fuel flow unless a larger ( automotive type ) diameter filter was used. Do you guys feel that the sediment bowl and carb inlet screen is enough? ( Yes, I know your Cub has been running for 60+ years just fine. :mrgreen: ) Not all Cubs are in a sterile trailer princess environment, and I just want to keep my carb working good.

Tell me what you would do. I'd like to do the braided SST so it matches my tin foil hat and faraday cage wallet ( just kidding )

Re: Fuel line material and filter question

Thu Nov 21, 2013 7:54 pm

1. I use the neoprene fuel line and a gravity feed in line fuel filter. I also replaced the sediment bowl with a ball valve. System has been in use for 15 years. Only had to replace the fuel filter once. The ball valve is a positive shut off. No fuel leaks. However, some folks think the neoprene fuel line presents a fire hazard.

2. The original sediment bowl and shut off system worked for 60 years. It's really your choice.

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:02 pm

You'll get a lot of opinions here so I might as well chime in too. I chose to go with a steel line because it is what was originally used and won't deteriorate like I've see rubber do an won't crack like a copper one will. Seemed like the best choice to me. Bottom line is, it's your tractor, do what you want.

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:11 pm

Short version of why not to use a "rubber" fuel hose is increased danger of fire. Rubber dries out, cracks, leaks right by the exhaust manifold. Or you could snag a branch and damage/pull lose the hose. Then with either case you add fuel to the fire (sorry couldn't help myself) until your gas tank runs empty through the gravity flow, which obviously can prolong and intensify the burn for quite some time. Steel is much more robust and less likely to fail or get damaged.

Fuel filter needs to be for gravity flow system not for something with a fuel pump.

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:21 pm

If you're replacing the gas line, TM Tractor sells both versions prebent. Unless there is something visibly wrong with the existing steel line, you probably don't need a new one. Remember that the threads at both ends are 1/2-20 and not pipe thread. If two screens don't keep the stuff out of the carb, I'm not sure that a third will either.

Bob

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:29 pm

Bob McCarty wrote: Remember that the threads at both ends are 1/2-20 and not pipe thread. Bob


Good point Bob. A 5/16" brake line is perfect for replacement. It has the correct fittings on both ends and can easily be bent to fit.

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Re: Fuel line material and filter question

Thu Nov 21, 2013 8:38 pm

ricky racer wrote:
Bob McCarty wrote: Remember that the threads at both ends are 1/2-20 and not pipe thread. Bob
Good point Bob. A 5/16" brake line is perfect for replacement. It has the correct fittings on both ends and can easily be bent to fit.

I cut the flange off the brake line and use ferrules with the supplied nuts. Will it work just screwing in the nut?

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:53 pm

I used brass ferrules with the supplied nuts just like you. Worked great.

Re: Fuel line material and filter question

Thu Nov 21, 2013 8:56 pm

Brake lines? Didn't know that, thanks for the tip.

Re: Fuel line material and filter question

Thu Nov 21, 2013 9:21 pm

Redcub wrote:Brake lines? Didn't know that, thanks for the tip.

Get a 20" length of 5/16" brake line from your local parts house with 1/2" x 20 threads on the fittings and also get two 5/16 ferrules to fit the line. Cut the flared ends off the line and remove, but keep, the fittings. Form the line to fit from your carb to the sediment bowl (you may have to cut off a little excess on the brake line). Once the line is formed to fit, reinstall the fittings and slide the ferrules on each end of the line. Install the assembly to the Cub. Make sure you slide the line into the carb and sediment bowl all the way before tightening. Do not over tighten! Remember, the carb and sediment bowl are made from soft metal and their threads can be easily stripped. I use an old fitting to seat the ferrules before installing on the tractor.

Re: Fuel line material and filter question

Thu Nov 21, 2013 11:02 pm

Installing the new fuel line into the carburetor fuel inlet before bolting the carb to the manifold will help to lessen the possibility of stripped threads.

Re: Fuel line material and filter question

Thu Nov 21, 2013 11:50 pm

I tried the 5/16 fuel line method, but had a hard time getting a rubber fuel line to seal around the stub tube at the carburetor fuel inlet. So I bought a nylon 5/16" barbed fitting. (Also available in brass, but I picked the nylon version) The threaded end was 1/4 male pipe thread, but this is nicely rethreaded to 1/2-20 with a die. A small O-ring in the carb fuel inlet, and some teflon tape around the newly rethreaded fitting, and everything seals nicely.

I'm not sure I'm persuaded by arguments re fire danger from rubber hoses. Most modern outdoor power equipment uses such rubber hoses, and it is not viewed as any particular danger. In my view, only reason for the steel fuel line is for doing a historic restoration as opposed to a working one.

Re: Fuel line material and filter question

Fri Nov 22, 2013 8:36 am

Jay,
I've really got to disagree with you on the rubber fuel line on new equipment. I work on and sell all types of new power equipment, and one HUGE differeince is that in ANY new engine, the fuel lines come in from the back, and the exhaust is in the front of the engine. The two are NEVER within about 6-inches of each other and the fuel line is never run near any of the hot parts of the engine. Often the fuel line is run on the outside of protective sheet metal or guards. On the Cub, your fuel line runs within about an inch of the bare exhaust pipe and manifold, which regularly reaches temps over 200-degrees F. Also, if you've ever run your tractor hard or for a long period of time like mowing, then put your hand on the bell housing part of the torque tube, just behind the engine block and under the fuel line, it will easily burn your hand. same with the hydraulic lines going from the pump to the touch control block. That fuel line runs right by some pretty hot parts, and yes, I've seen melted and scorched rubber fuel lines on a Cub right in the areas I've mentioned. It's the very first thing I replace on any Cub that I get, whether it's mine or not, but I'm pretty picky about things. They're easy to do if you take your time, and probably cost about the same as putting on a rubber fuel line, less than $10.00 anyway. Cheap insurance!

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Regardless, it's your machine, do whatever you want to it.

Re: Fuel line material and filter question

Fri Nov 29, 2013 6:59 pm

All of this information is good advise. I just happen to have the tag off of the steel brake line that I purchased at O'Rielly's two years ago.The number is PA-520. I did cut the steel line and inserted a lawnmower cutoff.This is on a verticle exhaust cub. I was looking today at my Cub with the underslung exhaust and it has what looks like a steel line, but is very close to the exhaust pipe.I'm going to rethink that one,I don't like even the steel line that close to the exhaust pipe!