Last night's post was titled "puttin' along," and was meant to refer to a motor going putt-putt-putt. I think the context makes that clear. It occurs to me, however, that "putting" (the motor sound or golf stroke) and "putting" (as in Puttin' on the Ritz or what one does in the Shot Put) are spelled exactly the same, with no indicators of how the U is to be pronounced.
The double-T is what makes you realize how "putt" is pronounced. But the T is doubled when adding the "ing," so that "put" gets a double T. And if one spelled it "putin'" in order to avoid that possibility, people would pronounce it like Vladimir Putin's last name ("pootin").