I'm stripping the paint off my 70 Charger & while most of the car has base red primer with gray on top, it appears that from the door hinge pillar forward, there is only green base primer. Is this something that was started in 1970? Not that this matters one way or the other, it's just something I've never seen on any of my 1968 & 1969 project cars.
Thoughts.....
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What you are seeing is a zinc chromate primer that was applied with a brush, before the fenders and hood were bolted on.
When Chrysler built the cars, the fenders, doors, hood and trunklid were all installed while the car was a bare metal assembly, then the car was painted.
Here's how they did it:
the bare metal unibody itself was all welded together.
The roof, rocker and cowl seams were filled with lead and metal finished.
A worker brushed the green zinc primer on the upper cowl sides, kick panel area, door hinge areas, hood hinge areas, and along the inner apron surfaces. Then the doors, fenders, hood and trunklid were bolted on and adjusted.
Then the bare metal car went into the cleaning, acid bath, rinsing process, followed by baking dry.
The car was then dipped in latex primer {usually dark grey}, up to about the level of the heater hose holes in the firewall.
This was washed off of the outer surfaces. { this is what fills the ribs of the floors with bubbly porous junk}
Then the car was sprayed with red epoxy primer, and then green-grey epoxy primer.
This was wet sanded after baking, then the car was painted with 2 coats of acrylic enamel and baked.
This is skipping a few steps, but that's the basic system Chrysler used.
The reason the zinc primer was brush painted in the cowl area etc was because the car was not dipped deep enough in the primer vat to reach those areas, so the brushed on primer was an attempt at rust prevention.
This brushed on primer caused lots of ugly drips in th engine bay, easily seen along the where fender bolts on. This is especially obvious on A bodies, E bodies and 71-72 B bodies because they have a horizontal bolt surface, and the dude who brushed on the green primer just let it slop down the inner aprons.
PS, if you work on 72-80 Dodge trucks, you will see the same drippy brushed green primer on the same areas
