| parrish | -- 06-18-2011 @ 11:34 AM |
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My economizer valve threads are stripped on a backup 94. They look to be plumbing thread instead of machine (makes sense). Anybody know the size and the degree of difficulty in cutting new threads in the bowl?
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| supereal | -- 06-19-2011 @ 10:09 AM |
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The power valve does not have pipe threads. If the threads are stripped in the bowl, it is likely the carb is junk. The bowl is of "pot metal", making the threads subject to damage if overtightened. Anyone installing a power valve has to be very careful not to cinch it down hard, or the gasket will be deformed, and leak either fuel or vacuum, in any case. The threads are fine, and the typical "fix" of Helicoiling won't work. Ford is famous for using odd thread pitches, such as 28 instead of the more common 24. When working on an old Ford, be sure to retain all the bolts and fasteners removed, or you will likely have to buy new ones from a specialist.
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| oldford2 | -- 06-19-2011 @ 1:59 PM |
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Well, since that portion of the carb may be history, I would take a Q tip and put a light coating of J-B Weld on the inside threads (not too much). Then I would put some light oil on the power valve thread, wipe off the excess and then fill the trheads on the PV with J-B Weld. Then gently screw it in finger tight and let sit for a while. I think when it gets in part way it may follow the stripped threads. Maybe a 1/2 turn out and in after 4 or 5 hours. I have repaired some threads this way. I think J-B Weld is tougher than die cast metal. So, what do you have to lose? John
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| Stroker | -- 06-19-2011 @ 3:39 PM |
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John's method will work, although I've found that over a long period of time (years), JB will succumb to the effects of fuel. A few years ago, Loctite made a product specifically to use for carburetor thread restoration. The principle and application was just as John described the use of JB. I'll do a little digging, and see if the product can still be sourced. The "power/economizer" valve is not subject to pressure, and is of course contained within the carb unlike a fuel inlet fitting. The failure of the threads of ANY FITTING UNDER PRESSURE i.e.: (pump outlet/carb inlet) should never be repaired using these methods,as a pressurized fuel leak is vintage automobile immolation waiting to happen.
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| Stroker | -- 06-19-2011 @ 4:03 PM |
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Loctite 442-28654: (Form-A-Thread Stripped Thread Repair Kit). Supposed to work in just about any environment except pure oxygen. Again, I wouldn't use it on pressurized fuel fittings!
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| oldford2 | -- 06-19-2011 @ 5:06 PM |
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Stroker, I googled the loctite kit number and ordered a kit from Betty Mills Company. $18 including shipping. Impressive writeup on it's ability to repair stripped threads. Since it is Loc-tite I don't think it is too exaggerated. Anyway, I will have it if I strip a thread and if I can remember where I put it. I am 72 but brain is going on 82. John
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| parrish | -- 06-19-2011 @ 7:45 PM |
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thanks, everyone. The carb has been sitting in a box since 1970...apparently it hasn't fixed itself yet. I'll give the loctite a shot.
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| parrish | -- 06-19-2011 @ 8:03 PM |
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thanks, everyone. The carb has been sitting in a box since 1970...apparently it hasn't fixed itself yet. I'll give the loctite a shot.
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| ken ct. | -- 06-19-2011 @ 11:29 PM |
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John,In 25 yrs of rebuilding 94,s i have NEVER seen or heard of stripped thread on a PV in one.I for one wouldn't try it. OMO.What say you guys,Charlie,ny,Henry 52,Strom 81,have you ever seen one.??? ken ct.
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| oldford2 | -- 06-20-2011 @ 3:17 AM |
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Ken, Have you ever seen the threaded holes that hold the carb sections together stripped? This might work to repair them. John
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| parrish | -- 06-20-2011 @ 8:14 AM |
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Economizer thread issues must be fairly common as the intruction kit carries this warning: "use care when tightening"
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| parrish | -- 06-20-2011 @ 11:34 AM |
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As I recall, the threads on the body to base are 10-32 and years ago I would grind down one side of a nut and use it to gain some traction. It won't save the Titanic, but it is better than a freely turning screw...
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| ken ct. | -- 06-21-2011 @ 12:37 AM |
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Sorry Parrish but,threads on body to CI base are 12x24 [2] and [1] 1/4x28,top to middle are 10x32. FYI. ken ct.Forget about fixing the PV threads its a waste of time.Deep six it.
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| supereal | -- 06-21-2011 @ 10:32 AM |
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There probably is little harm in trying repair stripped threads in a carb, but if any of those fasteners let go, there is a possibility of a fuel spill on a hot engine, leading to a destructive fire. Stripped threads are almost always a sign that an amateur tried to reassemble a carb and got heavy handed in the process, so there may be other problems, such as damaged idle needle seats, etc. We are seeing new repro carbs on the market, fitted with modern components. Not cheap, but better than a worn out original, both in performance and safety.
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| parrish | -- 06-21-2011 @ 9:41 PM |
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Ken: You are indeed correct that it is the top to body screws that are 10-32, not the body to base. As I thought about it, the 10-32 fix from years ago was to use 6-32 screws with nut partially ground to fit the (1) front and (2) side thread positions which are tight to the body section. I decided to re-visit that method today with the aforementioned carb and it worked like a charm...nice and tight. As for the economizer/power threads, I'll give Strokers Loctite 442-28654 a whirl just for experimentation...
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| parrish | -- 06-21-2011 @ 9:43 PM |
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Ken: You are indeed correct that it is the top to body screws that are 10-32, not the body to base. As I thought about it, the 10-32 fix from years ago was to use 6-32 screws with nut partially ground to fit the (1) front and (2) side thread positions which are tight to the body section. I decided to re-visit that method today with the aforementioned carb and it worked like a charm...nice and tight. As for the economizer/power threads, I'll give Strokers Loctite 442-28654 a whirl just for experimentation...
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| ken ct. | -- 06-28-2011 @ 5:34 PM |
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Carbs with a nut under the top screws look like cr*p. Tap them OS to 12x24x5/8. Head is just a tad bigger and not even noticable.ken ct.Course your super mechanic should know all this.
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| parrish | -- 06-29-2011 @ 7:42 AM |
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Thanks. Wish I knew a super mechanic...
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