I am wondering if there is great difference in the amount of time that our headlight doors stay closed. It depends on how tight our vacuum system is.
Mine give me only 3 days or so.
Curious to see where others fall and depending on the answers to this pissing contest I just might have to tighten the vacuum system up a bit. 
Mine stay closed until I turn the lights on no matter how long between nighttime excursions. Since I’m not driving it currently, they’ve been shut for about 2 full years now. Still full vacuum since I’ve not had a reason to switch over to electric yet.
Do I win?
Actually, I know of another guy on here whose doors stay closed even AFTER he turns on the headlights. 
WOW----I guess I have a real bad leak somewhere. 2 years might take the cake.
Need to investigate the guy who’s lights stay closed even when he turns the lights on though. This sounds like he might be cheating.
Yeah, yeah, yeah. I have a guy “working on it”…
To paraphrase good ole William Jeffa-son Clinton, “Depends on your definition of ‘cheating’…”… 
My vac system is gone/removed, and I haven’t bothered with a conversion yet, since I do very little night driving. If/when I do drive at night, I do the manual open thing. Works for now!
Sounds like this might open the door to the discussion of the word “IS” again too…
3 days is not bad… I have seen them stay closed for a year or so but that is very rare. Have you performed vacuum leak down tests on the individual components?
X2, I think that is doing quite well, Isabel is a similar amount of time.
I have a 69 coupe that when I restored the headlight stuff, I turned the springs around and installed the vacume canister in the other installation holes. This changed the system from the springs making the doors go up to the springs holding the doors down.
They’ve been down about ten years since I haven’t drivin the car in the dark since it was painted in about 1993. Holy crap…it’s been 20 years since those headlight doors have been up.
Don
I have not even started to look for a vacuum leak yet. I am kinda happy with what it is right now. There are a few more little things I want to do before this issue is addressed.
Thought it would be interesting to see what the community is experiencing.
Back in the day when my Cougar was complete and a car they would stay closed for about a week. After a week they would start to creep up and about after two weeks they would be two thirds open.
2 days, 9 hours, and 27 minutes
All four of my Cougars stay closed forever, unless the lights are turned on. The spring have been moved to the bolt near the factory spring retainer. So there is less of a spring trying to open them.
Mine have been closed for over two months with now sign of lifting. So I guess I’m doing good.
Steven
Mine stay closed unless I turn the the lights on. Will not close on their own though. Car has not been driven regularly for 23 years and they are always shut.
I changed all the vacuum hoses, actuators, and headlight switch. This system is sealed tighter than a duck’s butt! I don’t think they could be pried open after a month!
Hey Dave,
Could you be more specific?
Wow, mine are still the original actuators and hoses and they stay have stayed closed for months even before I changed the headlight switch and vacuum valve. Now I probably jinxed myself!!
Is this specific to some years only? My 68, which had one too-slow vacuum motor, the doors never opened after sitting, the longest they sat was over the winter, 3 to 5 months or so without the car being started. And that was with the passenger side motor being very slow to close, sometimes not even wanting to close at all. The springs for both doors were intact, though I removed them when I switched to electric motors.
Also, would it matter how often you opened or closed the headlights over the course of months or years? Every time you start the engine, the vacuum tank would be “recharged” regardless of whether or not you opened the headlights, right?
According to Ford (probably to keep warranty costs contained), if the 1969 headlamp covers stay down for 18 hours… they be good.
