Dad should be doing any dang thing you can get him to do! Especially as the boys hit about 8 or 9…they crave Dad’s attention then. You’ve probably noticed that. Whatever Dad’s interests are, encourage him to pass them on. In my house, that meant having a little guy around whenever he was building something. My husband isn’t too good at this part–he gets impatient and frustrated–but he’s gotten better over time.
Basically, there’s not gender split on what your boys should be learning from you or from their Dad (even sex can come from both parents, though it’s usually Dad who does the more serious stuff because it’s less embarrassing for the kid that way)–but they definitely should get Dad time, doing whatever they and Dad think is worthwhile, so long as it doesn’t undermine what you’re teaching. You have to come to an agreement on some things, like whether belching is funny or rude, whether it’s okay to talk trash about girls when out with just the guys, that kind of thing.
Really, even an hour fixing a bike or tossing a ball around or riding four-wheelers makes a huge difference. And if Dad can teach by precept and example how to treat women with respect and do kind things for others (and other things boys won’t learn from the general culture), that’s awesome.