Hello gentlemen, over the last couple months the starter on my 56 Tbird doesn't always engage when I turn the key. Most times it turns over, but sometimes I just get a kind of single click, then nothing.  It used to happen just once in a while, but now it occurs more often sometimes twice in a row. So of course I move the key back to OFF, and then try again. (I did convert over to pertronix electronic ignition a while back, and otherwise car has been running great.) I don't want this to become a problem....what should I check first?

Not sure but the big bugaboo with collector and vintage iron is corroded grounds, cables and connections. With restored vehicles thick coats of paint cause similar issues. The solenoid itself needs a solid ground reference too. It's impossible to overemphasize good solid cables of sufficient size and clean tight connections. If everything is straight then the starter itself may be suspect. When they get worn they start to drag and the current draw goes way up. This will mimic a flat battery. Check for cables getting hot. If they are old, replace them. Another problem today sometimes is finding good quality starters and solenoid relays. It's worth seeking out NOS or a proper rebuild that has attention to detail.

Clean the battery terminal connections if you haven't already. Check solenoid to see if 12 volts appear at the terminal where the cable feeding the starter is connected when you just hear the click.
Check connection at starter. My guess would be the solenoid is defective if your cables and connections are ok. Worst case the starter is bad.

I'm with Sandbird. If all connections are good then it could be solenoid contacts are burning out. Less likely, but next I would check the brushes in the starter if all that checks out.

Be sure to also check that the solenoid also has a good ground.

Lorena, Texas (South of Waco)

Thank you gentlemen. I took the wires off the solenoid, clean the connections, and reassembled. Multimeter hooked to the live side of the solenoid shows I'm getting my proper voltage when cranking. Car has started perhaps 20 times in a row over the last 3-4 days, so I'm thinking there was a poor connection somewhere. Glad it wasn't the starter, at least not right now. Thanks for your input.

I don't know how many times over the years I've reached down on a car and slightly moved the hot cable where it attaches to the starter to solve this problem. Especially on my Fords. As I understand it corrosion caused by electrolysis that builds up between the connections. Best way is to remove and clean all the terminals, battery, solenoid and starter. Glad you found it for now but I'd take a shot at the starter wire too just to be completely sure.

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

Thank you and will make sure to check starter connections too. Have to climb underneath anyway to resolve a slight power steering leak. Thanks and Merry Christmas to all.