My 70 Barracuda has hotchkis sport suspension installed with the aftermarket upper control arms. If I jack up the car and set it back down the wheels are straight up and down. But when I drive it a bit they splay back out. So I'm guessing something is loose. I tried taking the upper control arm off and putting it back on and tightening it down good to see if it would make any difference but no dice. I'm not very experienced with suspension. Any idea what would cause this? Thanks

Most likely when you set it back down the car is not settled back in the true right height position.

With a double A-arm (double wishbone) front suspension the wheel will move out and in when it is fully extended and compressed. And the camber will change when fully extended and compressed.

You could roll the car back 10-15 feet and then forward to the same spot and it should settle down. Also bounce the chassis a few times when moving it back and forth. The gas charged shocks will find thier center.

I would not think a person not well versed in suspension in his own words would notice a street performance setting of negative camber, unless something was wrong. The reasons however for the difference under the OP's situation has been explained IMO.