Doug,
They shouldn't mess with you at all. Wipe the grease off, wrap them in plastic, pack them in a thick cardboard box and then check them as baggage. I think the max weight at the moment is 50 lbs but you might want to check that number with the airline your using.
With the box they might ask you what's in it. Car parts aren't illegal contraband so you should be OK. They can tell you on the phone if there are any possible downfalls to doing this. If you wanted to go even more incognito you could find an old suitcase at a garage sale for a few bucks.
I once carried a front grill from a 70 Torino on a plane with me. I got some curious looks but noone had any problems with it.
Heavy with sorta/kinda pointy ends might be a problem for carry on.
If bringing them with you won't work you could always ship them to yourself.
Cheers
Bill