timflury Posted April 19, 2011 Posted April 19, 2011 Hi guys, I have the 6 horse engine out of my Wonderboy now and I have it torn down to a short block. It looks like there was something in the nature of JB weld in the 3/4" pipe threads. Before I send out my block for freshening up,,,,,, Does anyone have any tips as to the repair of the 3/4 pipe threads at the exhaust port for the muffler???? I might be considering drilling out the hole and tapping 1" pipe thread and using a threaded reducer. If I can't restore these threads, there's no call to have the short block rebuilt.
Mel_W Posted April 19, 2011 Posted April 19, 2011 I'd try a pipe tap in those threads to see if they clean up some. If they do seem a little large and sloppy they might still be alright because of the taper on pipe thread.
RayS Posted April 19, 2011 Posted April 19, 2011 I assume you have already tried chasing the treads. Looks like there is enough material there to drill oversize and put in a reducer.
timflury Posted April 19, 2011 Author Posted April 19, 2011 Ray, I took pictures shortly after I removed the muffler. I have a tap in my toolbox at work and I'll update my pics after I clean up the threads.
kilalove21 Posted April 19, 2011 Posted April 19, 2011 since npt threads taper, just tap in deeper and use the same size pipe. i would think that would be better than going bigger and reducing.
rokon2813 Posted April 19, 2011 Posted April 19, 2011 You can also cut the first few threads off the pipe so you are essentially using a bigger pipe, because of the taper
Willy Posted April 19, 2011 Posted April 19, 2011 If you are taking it to a machine shop they will probably boil it out,that should loosen the rust and carbon. You have allot of good thread there,once it cleaned out, you can run your tap in to renew the thread.
timflury Posted April 20, 2011 Author Posted April 20, 2011 WHEW!!! I got lucky. I just had to run in a 3/4 pipe tap. I left message threads on other sites too. One suggestion that was brought up was to Helicoil the pipe threads. I learned something new,,,, They do make thread repairs for pipe threads. Now I just need to find me a locknut.
ka9bxg Posted April 20, 2011 Posted April 20, 2011 Same lock nut as conduct for electrical. I have cut a few threads off a pipe tape so I could get deeper threads.
timflury Posted April 20, 2011 Author Posted April 20, 2011 FYI Bob, I'm an electrician.:D:D I wonder if I should find an aluminum, or stamped steel locknut. Shortly after I snapped the photos and loaded them here, I was out the door with the shortblock and off to the machine shop for the valve job and cylinder work. We'll see what they can do for me and how well they'll be able to find parts.
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