Almost There.....

Tue Apr 13, 2004 5:15 pm

I am finished reassembling all of the external engine parts, so after they are all installed on the cub, it should be ready to run.. :roll: I want to use a small auxillery tank to get it running off of, but I need to find the size of threads in the carb fuel line inlet so I can screw in some kind of pipe plug with a nipple in there to run a rubber hose to the small tank... Anyone know what I am looking for here? Also when I actually start the cub, I am thinking of using an externally moutned 12 volt coil for the mag, will that hurt anything? - the old 6 volt externally mounted coil is junked.. With a 12 volt battery grounded negatvely can I just run a single wire off the positive post of the battery to the post on the coil? I am planning on pull starting just to see if it will run I will do all the other wiring later... Also the postive and negative leads on the coil, which one goes to the mag terminal, and which do I hook the battery to? I just want the simplist wiring setup I have to use to get this thing running.. I would use a 6 volt battery and coil to start it, but i have 12 volt a car battery right here.. thanks a bunch

Peter Reynolds

Tue Apr 13, 2004 5:48 pm

Congratulations on getting this far Peter! If memory serves, the fuel line fitting threads ar 1/8" pipe threads, you can buy a fitting with a hose barb on it to make this job easy.
The coil is grounded throuh the points so if your temp set-up is going to be 12V negative ground, connect the negative to the mag terminal. Be sure the internal coil of the mag is disconnected. The plus side of the coil goes to the battery positive terminal.

Tue Apr 13, 2004 7:23 pm

I don't think the threads on the fuel lines are pipe threads. I might be wrong, but am not going to go check it. If so, a pipe nipple would probably ruin the carburetor top.

Get a short piece of brake line which will be the right size and use a compression fitting that will fit properly.

Tue Apr 13, 2004 7:31 pm


This may confuse things, but it is NOT a pipe thread. I may have to take my favorite Grandson to the woodshed again! :lol: :lol: :lol:

It is very close to 1/4" pipe, but isn't a match and trying to use a pipe thread may (will) damage your carburetor. The correct thread is 20 TPI but the pipe thread is only 18 TPI. Here's where to get a correct thread to use. Get a nut and ferrule (olive) for a 5/16 brake line along with a short piece of 5/16" O.D. tubing and you will be good to go.

Be sure to call in all your friends and relatives for the big occasion. Image

Tue Apr 13, 2004 7:40 pm

Sorry Grandad! I shoulda went to the barn and looked. I'm tryin' to work with an apparently only semi-functional brain. Lash away! Hope Peter didn't ruin anything.

Tue Apr 13, 2004 7:52 pm

Thanks for the quick and helpful responses gentlemen.. I am getting really excited about getting this old cub rolling again, and I think I am right on track.. After three years, this thing looks like it is finally going happen. What a hurdle it has been for me to get over my own doubts and pescimism about getting this cub back together, but I am finally on the home stretch. Today I made a list of the final parts that I am going to need and set a goal of trying to start it in two weeks. I have some pictures of me and the cub that I am going to try and learn how to post soon as well.. Thanks again for the advice on the carb and ignition, and I look forward to hearing the engine run for the first time. The man who I got the cub from doesn't even know that I have it back together - I am waiting to suprise him with it when it is running outside his porch. Last time he saw it it was in hundreds of pieces. Again, thanks for all your support and advice, I have learned much from all of you, and wisdom that I will not soon forget.

Peter Reynolds
1949 Farmall Cub
:) (Looking Like a Tractor Again) :)

Wed Apr 14, 2004 8:40 am

Hi All
I hope everyone is doing well, or as well as possible. I had a question for George. If the 5/16 20 T.P.I. brake line thread is the correct size for the carb, is that a compression thread where you say to use a ferrule, Or is 20 T.P.I. a flare thread, as the ends on a brake lines come with a flared end on them ? I was also wondering is the thread on the bottom of fuel tank pipe thread where the fuel strainer connects, in case folks thread a pipe plug in there when they have the tank off and want to clean or seal their tank ? I know I am always asking questions about threads but hopefully someone else out there wants to know also, and we can do things correct. THANK YOU !! for your time, and knowledge Paul K. in N.H.

Wed Apr 14, 2004 9:05 am

Hi again
I also forgot to ask what is the thread where the fuel line connects to the strainer assembly, flare or compression ? THANKS Paul K in N.H. :oops:

Wed Apr 14, 2004 9:58 am


In my note to Peter, I mentioned the ferrule (olive, as some call it). Yes, both ends of the fuel line are 5/16 O.D. compression. That 5/16 fitting is nearly 1/2" diameter, so it's easy to see why it could be confused with 1/4" pipe. Image

To further complicate things, the thread into the tank really is a tapered pipe thread... 3/8 nominal.

Wed Apr 14, 2004 10:26 am

I learn from you every day, and I know many others would say the same. Paul K. in N.H. :D