Is there a quick way to install earlier Fedora kernel packages?

Go the Fedora's Package Build System, called Koji, and find the kernel you are looking for here:

(edited): https://koji.fedoraproject.org/koji/packageinfo?packageID=8

Then scroll down the the x86-64 architecture that you are looking for. Then you have two options; Either download what you need (kernel, kernel-core, maybe kernel-devel, kernel-headers, kernel-modules) to your local disc, and then use dnf to install the kernel:

It would look something like: dnf install ~/Downloads/kernel-4.6.6-300.fc24.x86_64.rpm

The process of how to do it is described in detail in the Fedora Magazine. You should not only download the package with the kernel but all three packages with kernel, kernel-core, and kernel-modules.