Have any of you figured out a way to straighten the part of the fuel pump casting bent down by over tightening the bail wire that secures the glass bowl without breaking the casting? The casting of one fuel pump I saved for internal parts is already irreparably cracked so just to see what would happen I tried bending a part of the casting cold and it broke like a piece of glass. Ferrous metals go through color changes with increasing heat so there are no surprises when heating it to form or weld it. Aluminum, however, forms an oxide when heated that has a higher melting temperature than the aluminum itself, concealing what the aluminum under the oxide is doing. The metallurgy of a fuel pump is a mystery to me so I don't know if it will become malleable when heated or what.
An option is leaving it bent and truing the inner surface that the glass bowl seats on using the milling machine and rotary table.
I've figured out a simple modification to strengthen the bail attachment area of the casting to prevent further bending. It's a barely noticeable, simple piece of aluminum flat bar bridging across the casting giving solid support to the bail attachment areas. With that piece of flat bar in place tightening the bail will not bend the casting.
If any of you amateur engineers/machinists/welders out there have any suggestions I would appreciate hearing them.
I have straightened a glass bowl water trap only (not attached to a pump) by gently clamping the body between a old valve spring and a piece of flat steel and only warming the alloy. Tony
Ray, I know how much you like to fix and rescue stuff, but if you just want a useable fuel pump casting, I have several and I would be happy to send one to you.
Any die-cast (aka pot metal, white metal) part can be straightened using the method. In addition to carburetor air horns, bowl covers, fuel pump glass bowl seats, vacuum wiper housings and tops. All you are doing is quickly reversing the slow warping that occured over years by heating the metal to its softening point. Yes, softening and not melting. Think of it as a stick of butter in the refrigerator. Stiff and not yielding. Put the stick on the counter to heat up and it softens still retaining its shape. But too much heat and it is a puddle.
The easiest way in many cases is to support the casting and use a weight to push down on the supported casting, heat in an oven to 400 deg. F (450 deg F is too much for most zinc based alloys) and let cool. Doesn't take much weight. Too much weight will cause the spot where the weight rests to sag as well. As an example with a fuel pump just use the glass bowl as the fixture. It has the surface you want to match. A metal ring, hex nut or washer or two can be used for the the weight. Pieces of wood or metal can be used to keep the part upright and supported.
For vacuum wiper housings it is necessary to make a plug to fit the desired cavity dimensions. Too narrow or wide are both bad.
Thank you both very much for responding to this inquiry. I have some ideas for undoing the warping that has occurred. They involve trying to reverse the deformation resulting of many decades of use, re-machining the part of the casting where the glass bowl seats to get a perfect seating surface and making a "yoke" to bridge across the glass bowl seat to give unyielding support to the bail.
Mike, I will send you an email. You are right that I do "...like to fix and rescue stuff," To me , that's what this hobby is all about; valuing the vehicles of the past and giving them new life.
Chipper, I don't have your email address so I will send you a personal message that I hope you will check out.
Hello All As I have rebuilt a few AC fuel pumps ( just finished a 35-36 a couple of weeks ago and attached pictures), almost every fuel pump I buy or a customer sends me that is used has the flange for the glass fuel bowl bent. This is even on the new updated fuel pumps with the extra support web cast in from bail hole to bail hole. As I have welded die cast metal before and as Chipper noted that you just have to soften the metal to get it back straight, I came up with a method that I use all the time that is quick and works with out an oven.
Once I get the fuel pump cover precleaned, I mount a small 2 jaw puller in a vise. I did make a shoe that is half mooned at the bottom to go around the inlet port boss with a raised square stock welded to it that puts the pressure point above the check valve boss to get a center pull between the bail holes. A large nut will do the same thing. The jaws of the puller are centered on the bail holes and then the puller is snugged up. Using a 1500 watt hot air gun on high, I get it about an 1 inch from the casting and then heat it in a circular motion all the way around to get the complete end of the cover hot and then gradually tighten the puller bolt. I go about an 1/8 turn at a time. You can fell when it is to the end as it gets harder to turn. Usually a full 1/4 turn will straighten the cover. Sometimes I have to heat and cool is a few times to get it flat. So far I haven't broke one except the first one I tried cold. While I am letting this cool to check it, then I work on the other parts of the fuel pump. This is a little tricky to do but is works for me. Bob@marxparts
