640 Carb fuel line threads

Doug (OH)

Member
Hi everyone. The threads for the fuel line on my 640's carb are starting to get a little sloppy. I've already cleaned them out with a tap once before. Just wondering, has anyone had luck drilling out the carb and installing a helicoil insert? Any other ideas or suggestions? Thanks in advance for the help.
Doug
 
That is a 1/8" pipe thread. I hope you haven't run something else in it???

There is no such thing as a pipe helicoil to my knowledge??

Zane
 
The threads in the carburetor where the strainer fastens?

I'm pretty sure they are 3/8 fine thread.

I have a 641 and a 4000. Neither have pipe threads.
 
Hi guys, I think I had the right size tap for the thread. Between my dad and grandpa, I've collected a lot over the years. The brass fitting still snugs up real nice. The tractor never had a sediment bowl since I've owned it. Finally bought one and made a banjo bolt according to some info from folks on the board, here. Things still snug up and no leaks. Just a little sloppy. The bolt is spec (except for being a grade 5). It does not like the hole as well as the brass does but still works. It will work as is, but I was just wondering if there were any options for fixing the hole/fitting in case it gets worse. Has anyone had a similar problem before with a less-than-perfect carb fuel line hole?
 
I have a Jubilee carb that someone made work with epoxy.
I don't know what kind of epoxy it is.
It is an ugly job but it doesn't leak.

I have made one work by sweating brass into the threads with
a torch, re-threading and cleaning them out well.
Not a job to be done before a thorough cleaning of course.

That one used a brass inlet too. I'm not sure how well either
would hold the banjo bolt with the sediment bowl hanging on it.

mvphoto26230.jpg
 
My 640 has 1/8" pipe threads. I'm pretty sure they went to the banjo fitting on the "1" series.
Usually when pipe threads are bad, you just tap deeper and you're OK, unless you run out of "meat".
 

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