Heater core outlet tubes hitting the back of the tall valve covers. Has anyone done anything trick, like soldering AN fittings to get a tighter turn coming out of the box?

That sounds surprising.

I just changed my heater core and there was a tight bend on the tubes and plenty of valve cover room.

Is your car a small block or big block? Any photos of the problem?

Sounds like you have the wrong heater core.

Post a picture.

Yes, here's what I did

-10

It's a small block. The bottom hose was fine it's the top hose that was being kinked.

I think the best fix is to install a big block box and core. Making it alot easier to remove covers to adjust valves, if need be. Thanks for all advice!!

Or you can just remove the core and hoses, get a cleaner look too. ( I removed mine )
You dont drive it in the winter anyway right ?