RandyS

I have finally begun working on the hood of my 66 442 Project (saved the best for last ). There was quite a bit of filler in roughly an 18" circle in the center and after removing it found quite a large 1/8" to 1/4" depression with a few very small dents. Upon flipping the hood over, I noticed that the material that normally creates the spacing between the top skin and the hood frame is missing in most areas. (thus the sag) The top skin oil cans very easily in several areas. I want to replace the missing material to straighten the skin as much as possible. Do any of you know what was used to create the gap, and approx what the gap is supposed to be?

Bernhard

The factory used a early form of panel adhesive.
The problem with any modern adhesive is once you apply it will you be able to correct the height once it sets or is it there forever.
What I mean by this is if you get it to high will you be able to remove the adhesive and give it another go.
It is always best to leave the surface a little low 1/64 to 1/32 that way you can cheat with high solid primer of plastic filler.
If it is to high you have to lower the skin manual by removing the adhesive.
What ever adhesive you use practice with it first,find out about its workable caricaturists.
Remember you can not fill a high spot,yes you can shrink a high spot with a torch,but it can go sideways on you quickly on a flat hood.
Ask me how I know
Make a spacer and fine tune the spacer till you have it were you want it, use the spacer when you fill the gap with adhesive.

All body dolly work should be complete before.you use the adhesive, the adhesive should be auto body grade.
Once the adhesive is set you can you can fine tune with the body/slap file you have to.
Don't over work the metal slow and light on the tools till you have it were you are happy.
Good luck

kitfoxdave

Many of the modern adhesives will release with heat applied over 300 degrees F, or extreme cold (dry ice).

coppercutlass

FWIW you have to be careful. There are specific material that can be used that are non high solids meaning they will flex. For example if you use something like window urethane under the frame ., once the hood hits the sun and the metal expands the window urethane wont and you will have low and high spots all over the hood. 3m sells specific foams for pillars and areas like under the hood which expand to various specific stifness rates. All metal work must be done first just like bernhard said. I mentioned the window urethane because a guy i worked with though it was a good idea to use it between the door frame and the door skin and it was a black car. the car sat in the sun after it was painted and you could see a defined line along the door. I also know this from personal experience on a hood i did for my ex's k5 blazer. luckily the hood sat so high the only way to see it was from the roof of the truck but where ever i did the blobs of urethane on the frame low and high spots where created due to the expansion and contraction of the steel in the hot sun.