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The mysterious "dark" knob

Random question that came up in discussion this morning. Created an account here just to be able to ask this to the collected experts of the internet.

I remember, long long ago (okay, so not that long ago, but it sounds better that way), I was taught to drive stick in an old (late 60’s) Toyota Corolla. Manual everything. It belonged to the girl I was dating at the time, whose father had saved that car on purpose in order to have a car he could pass from child to child to teach them how to drive in a not-a-deathtrap-but-old-enough-that-if-you-wreck-it-it’s-not-a-huge-loss car. He also loved the fact that he could do all the maintenance on it himself - no computers required, just gallons of elbow grease and know-how.

Anyhow, I remember that car having a knob on the dash labelled ‘Dark’. My girlfriend told me before she let me drive it to never, ever, touch that knob, since it had something to do with oil and gas and the engine and badness if it was adjusted. It’s now been long enough that I can’t for the life of me remember what that knob actually did, though, and searches for “dark knob” on google return … somewhat more lascivious results than I care to peruse looking for an answer.

My curiosity has now been piqued - anyone out there know what that knob did, or have a link to a resource online I could use to read up on it?

Some Saab’s years ago ('87 ish) had a button to black out the dash to aid night vision. Perhaps “dark” knob was a way to turn down the dash lights, or turn them off.

Perhaps this Sunday mechanic dad had installed a manual choke and for some reason the knob was labeled “dark”. That might account for the “oil and gas” comment in that running with the choke on in a warm engine causes a rich fuel mix and the excess gas runs down the cylinder walls and gets into the motor oil, in effect thinning out the oil and polluting it.

Just guessing based on the info provided.

Maybe it was a ‘break up’ button and this would happen to you when she pressed it:

Many cars have dash lights that either dim or get brighter after dark, could that have been the reason for the button?

here’s another vote for dash lights dimmer.

Anybody who remembers enough of the late 60’s to know what the “dark” knob on a Corolla did wasn’t really living in the late 60’s.

It sounds to me like a black knob on a manual choke cable as that would have big affect on the gasoline/air mixture. I have no idea what the “dark” part of that would mean but knobs for many things are often interchangeable so it’s anybody’s guess.
Manual choke cables were pretty common back in the day. Even cars with heat operated chokes were converted to manual chokes when the car owners did not want to continue dinking around with problematic chokes.

A gearshift knob I used to use on one of my old Harleys had “Hyster” lettered on it and was from a forklift so anything’s possible.

I don’t know the answer, but you could try searching the internet for a late '60s Corolla for sale in your area and, if you get lucky, stop by to look at it.