When I first got the car (alleged) rebuilt 383,, the oil was CLEAN. After got it running (2 min) the oil was milk.Changed the 0il & filter. Ran again,, 3 min @ a time for maybe 15 min. No oil comes up to the valve covers. So Dropped the oil pan,Cleaned the screen(dont ask It was gray sludge((which I think is part of the problem)))Pan is back on (screen is clean) Starts Runs No oil in the valve cover. Yeah get an oil pressure gauge. Then what??
Cracked block or head
So you are satisfied that the top end is oiling now? I’ve been pondering what would cause that problem and other than some sort of crud blockage I’ve come up with the following:
1. Spun a cam bearing.
2. Improper/damaged head gasket/installation.
3. Rocker shafts installed upside down, (side to side doesn’t matter, I think, working from memory here, been awhile since I’ve done a B block).
Milky oil/sludge does kind of sound like an internal water leak as Michigan Bowhunter was hinting at. I’ve had the problem of head gaskets not sealing until the engine was brought up to operating temperature the first time. Since it was supposedly a fresh rebuild and you were only running it for short periods at first this could be the deal on that, especially since it seems to have fixed itself. It’s possible.
I’ve seen GTX’s with power windows but never a ‘runner, although I’m almost sure they were available. Aftermarket perhaps? Should be easy to tell.
Bummer about that fender tag. Maybe there is a build sheet someplace, they are usually stuck in the springs under the back seat. Doubtful, after all these years.
Checked out your pictures, thanks for those. One thing bothers me, Roadrunner engines were orange, I don’t think there were any exceptions in 1970. I could be wrong about this.
Keep going, the damn things always get done...eventually.