fixing an oil canned hood

[WagonCrazy]

Let's go thru your questions one at a time:

Have you used a profile template or 3’ ruler or ?? To see how the front to back looks?

Yes, I have a metal 3' ruler that I'm using in the video below.

Is the spot you planished a high spot now, is it a gradual crown front to back as it should be?

Drivers side...It doesnt' appear to be high. It DOES appear to be a gradual crown from front to back as it should be.
The very center of the hood is now strong (no flexing when pushing) and (using the ruler) it appears to be the same gradual crown from front to back as the driver side (see video below)

Now check the loose area the same way.

The loose area (passenger side of hood) is slightly lower. It doesn't have as much crown as the center or drivers side does.

Now check across, left to right in various positions to see if that loose area is dropped any.

Loose area (passenger side) is definately down a bit (lower than the driver side area)

More importantly, was the “center” planished too much that it’s pulling the low?

I havent planished the center at all. only the driver and passenger sides in about a 8 inch diameter area (each) where the carb fire would have occurred.

Take a look at the video below and tell me if I should be planishing in the center next...to spread the steel towards the passenger side (to tighten that up more)?

[MP&C]

On your ruler, if you lay it over flatter (not on the edge) at about a 45* angle, it will lay down naturally to follow the contour of the hood. With it in this position you can better determine high spots or low spots, over using the "rolling arc" technique. Then, you'll need to do this same "lay it over" in the side to side orientation at various locations, I'd suggest 6" increments. If it is low on the passenger side, stretching the middle won't fix it. Can you do the ruler test again, laying it over?

[WagonCrazy]

Lets try this again...

Overall, the contour is within 1/16 inch of where it should be, but there's just such an obvious soft spot on the passenger side. How to stiffen this?

I laid the straightedge over flat as you described in your last post. But I dont' have a short enough straightedge to do the side to side lay-flat test.

Take a look:

[MP&C]

To clarify...

On your ruler, if you lay it over flatter (not on the edge) at about a 45* angle

You've gone from one extreme to the other. Up on edge will not match the profile of the crown, laying flat does not support the ruler, so it will fall into the low spots and not show them effectively. At a 45* angle, the ruler has some support and will follow the profile of the hood.


Now, before doing anything else, we need to check left to right, Drivers side to passenger, whatever you'd like to call it. I understand your ruler will not fit between the bullet "tunnels?" but go to your nearby hardware store and get a piece of 1" x 1/16" x 4' aluminum flat bar. Before buying, sight the length just like you're buying 2x4 lumber, make sure nobody has bent it. You need it perfectly straight. When you get home, cut it to fit between the bullets, and check the profile left to right. Start at the back of the hood, LAY IT OVER ON A 45* ANGLE, and check for light shining under, indicating a low spot. Come towards the front of the hood every 6" and re-check.....

[WagonCrazy]

Gonna have to get a shorter straight edge, and gonna have to have my wife hold the camera (closer) while I do the 45 degree slide trick across the hood with the straight edges.
Got to see if Lowes or Home Depot has the straightedge material. Back at ya later today. Thanks Robert (for your patience). I'm intriqued to see if I can get this flexing gone.

[WagonCrazy]

Try this one...

[MP&C]

OK, how about another video... This time take your right hand and move it all the way to the right end. Where you have your hand does tend to push down, so LIGHTLY holding it down on the end should show a more accurate reading of where and how much the low is... Next, move the light to the far end of the hood so the light coming through the gap is more visible (if this doesn't blind the camera)

[WagonCrazy]

Try this...

Almost seems slightly high right down the center, but definately lower on the passenger side as we slid the straightedge towards the back of the hood...

[MP&C]

Looks like it's low on both sides, or perhaps center it stretched too much. Go back to the front to back orientation with your ruler and check the center for any low areas. If that looks ok, I'd say leave the center front to back alone. I have a feeling it's good based on how well it got rid of most of the oil can.


In your latest video, if that is light I'm seeing on drivers side as well, you may need to stretch both sides, but using a more open grid as you won't need that much. It doesn't have the focused shrinking like what the carb fire produced. I'd use about a 2" grid and see where that leads you. Don't focus on any one area lest it produce an isolated bulge. Keep your planishing here moderate to light so you can SNEAK UP on the proper crown. If it needs more, offset an inch to planish new metal. Keep checking as you just did using ruler at 45* angle, side to side as well as front to back to verify where any lows remain.

Having the light toward the front but hanging up and aimed downward may help eliminate blinding you.. With the ruler leaned toward you (the direction you are standing) the ruler will cast a shadow so any light will be easily seen..

[WagonCrazy]

Been planishing in various spots as you mentioned above, but it doesnt remove the generally weak steel-low spot on the passenger side. After working it as you suggested, it didnt really raise itself up or stiffen the metal enough. So I got curious and frustrated at the same time, and tried a little heat from above and it raised it right up and stiffened it when cooled. So I did that in several places around the passenger side weak spots and its now within 1/16" of where it should be and no longer oil canning.

I know this is counter to what you've suggested all along. But the metal seemed to be stretched downward so much that it needed shrinking to raise itself back up and stiffen it. So don't be frustrated with me here, as I am learning as I go and figured this hood may need to be replaced at some point if I can't get this fixed, so I tried the heat...

I'm going to spray 2K primer on it now, and then put the inner brace back on (spot welds around the perimiter) and then put it on the Nomad for now.

Later on when this car goes into the final disassembly and paint prep mode, I may end up replacing the hood with new sheetmetal if I can't get it straight enough for final paint.

This was a good exercise though, and taught me alot about properties of sheet metal and its movement. Thank you for your patience Robert. Greatly appreciate that.