I would be very skeptical that the brass nuts are holding tight. Don’t try to torque them any more, it’ll just ruin the threads on the aluminum fitting. I used to pick up water tubes that had the original nuts on them, but I’ve used up all I had.
Try loosening the nuts to see how tight they are. If they are tight, they are probably the correct ones. If they are loose, or the threads on the fitting are buggered up, you’ll need to find the correct ones.
I went through the same issue with a ’29 Fastwin I still have. Aluminum tubing is available from McMaster Carr, but the nuts are not.
T
