Need some tips on weldind together a 2-piece hood on a 51 chevy. I tied one a couple of years back and had a bad oil canning problem. I tdid the usual tacking alowiing time to coll between tack welds. Was wondering if the folded edges on the inside of the hood should be removed before welding together? Any help would be appreciated, finally found another hood and don't want to screw this on up.
The 50 I'm working on now had bodywork done by someone else, but he tack welded some large flat washers to the outer sides of the bottom of the hood (at the bottom of the edge), in two places on each side, and then tied the sides together tightly. This kept the hood from spreading apart and flattening on the top. Came out ok...not perfect. He left the folded edges in the center.
I have never welded a hood BUT just thinking about it for a minute I would not take out the folded center section if you don't have to because I believe it gives your hood some needed support. Mine was taken out and now flexs when opening from all the unsupported weight.
I'm not a trained welder by any means but what I did was this. Low heat setting and go very slow cooling the area with a damp rag as you go. I would tack one end, cool it, then go to the opposite end. Just don't get in a hurry and try to do it in half an hour. Bill
Try and find some metal the same thickness. Use low heat and practice on this till you get it so you don't end up looking for another hood.
I went slow on mine, I made small welds about 1/4 an inch long, and about 10 inches apart, one p*** down the hood, and I let it cool for about 15-20 min. before I repeated. I clamped the seem all the way down about every 5 inches.
I have never welded a hood yet, but have welded the low-to-no crown roof, when i extended it. I tig'ed it, and that was fun. I had a **** to **** fit with no gap, and it wanted to overlap, so i split it just barely. I would tig about 1/8"-1/4" then as soon as the torch was extinguished, i cooled the weld with a wet rag, then hammer and dollied it. The biggest thing is take your time. Do 1/4" at MOST. So what if it takes you 3 days to weld the hood, itll look nice. "You never have enough time to do it right the first time, but you always have enough time to fix your f*** ups or do it again"
I recommend cleaning the joint REAL GOOD first then tack the hood to fenders on both sides in a couple places. then turn the mig up on high and zap a spot weld lasting just as short as it takes to let go of the trigger then move along about 4" at a time doing same thing. when across the length start over and do same quick spot in between each of previous spots.clean the soot off wit wire brush each p***- I lay my left hand on the worked areas as I weld and if it becomes uncomfortable to lay your hand on it anywhere its too hot. It will take a long time goin this speed but you will not warp it doing this method.MAKE NO BEADS AT ALL. Also be careful and take a lot of time grinding the welds down as this can impart enough heat to "draw a wave" in the middle of your hood
The advantage to taking out the edges and having a **** weld is that you can more easily reverse the damage caused by the heat from welding. You can always put a fabricated brace back in after your finished if the hood needs it for support. You could even use panel bonder to do so.
Ditto to the above. And the flip side to that is: if you leave the edges, and it oil cans, you will now not be able to hammer and dolly the seam to remove the oil canning. I had a friend who welded his 51's hood like you want to, with the seams intact. It oil canned. It could not be fixed. Bondo is not your friend, in this case. Cosmo
If you quench the weld you are actually accelerating the shrink that is caused by the heat, and possibly making the metal more stiff. You want to stretch the weld area, not shrink it. If you weld up a gap, you are going to have a lot of pull into the weld area which is not a good thing. Go with a perfect fit, and if you are mig-welding a very hot tack, let cool, jump around and repeat. You will get some shrinking this way, but less than if you left a gap. Do not quench! If mig is your method, you might consider a heat sink behind the weld. A piece of 1/4" X 1/2" flat bar formed to fit would help (must have a gap so the weld is to the flat bar as well), but even this method will cause some shrinking. Gas-welding or tig, then hammer and dolly is the best way to do this. If you have problems with oil-canning, you can chase them around with a shrinking disc and a hammer and dolly. John www.ghiaspecialties.com
IF- you don't warp or draw it you will not have to hammer it back into shape.......... I cut hoods to lower the nose requiring two full length cuts in addition to the middle seam-It can be done- I spend a day welding one of thes....its easier welding that slow than correcting the damage done from too much heat.
you know the old oil cans that when you press on the bottom that go klink,klink. Well it's like that. The panel will not hold its' shape and with very little pressure it reverses. It is commonly found on very low crown panels, like hoods, door skins, roofs, some deck lids.
i warped mine pretty good...i got the oilcanning back tight,but dented it up pretty good doing so. i had to put some filler on it.....i spent three days welding and it still warped...hopefully it will be ok
Helped someone do a cut and shut, when it was time to weld across the roof, he used some ¾ copper pipe laid each side of the cut about an inch apart, hooked up a hose and run cold water though it. He would do a tack and I would hold a dolly on the spot while he taped the weld with a small hammer (light taps working from the edge of the weld into the centre. He moved to an different area after each weld- the water running though the copper pipe stoped the heat spreading from weld area. It took a long time to do it but the result was very good.
I have done it on a 51 hood,left the folded edge where it was,and tacked it up. Took some time,but came out pretty ok. no oilcanning,but I got a little dent near the front edge. (typically,when its nearly finished,its hard to let it cool properly.. ) Be sure to push the two halfes good together,the distance between them may vary pretty much when you start.
Thanks for all the advice! I plan on doing the hood in a couple of weeks, I'll let you know how it turns out.
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