How much vacuum needed to open headlights?
Team Owner
Joined: Jul 2001
Posts: 182,997
Likes: 88
From: Lakeland, FL
Cruise-In IV-V-VI-VII-VIII Veteran
St. Jude Donor '03, '06, '17
I had pretty radical engines in some of the C3's that I've owned and never had a problem with vacuum.. It'll always be enough to open them...
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Drifting
Joined: Mar 2003
Posts: 1,608
Likes: 3
From: Canberra AUSTRALIA
St. Jude Donor '05-'06
Originally Posted by wcsinx
In truth, you need very little with a non-leaking system. Before you try anything else, make sure none of your hoses, fittings, actuators, or relays are leaking.
I have tested some of the vaccum components with a MightVac and seen operation at 5-8 Inches of Hg. Mine leaks like a sieve (both relays shot and RH actuator dust boot split) and I have about 10-15 at idle and the lights work OK.
Biggest improvement I notieced was new hoses as they fit nice and tight. Next thing is to replace/repair all the actuators and relays but they can easily run over $500 if you use the AC DELCO which is a MUST.
If you are on a real budget. Then Cutoff the last 1/2 inch of the vaccumn hoses and reseat them, maybe use loctite to get a good snug fit. And serach on the internet for the Norwegian Corvette website on how to rebuild Relay Valves. You can use one realy up front instead of two. Lights will be slower but it does work.
Good Luck,
Pete
Melting Slicks
Joined: Nov 2003
Posts: 2,668
Likes: 119
From: St. Charles Mo
CI 5 & 8 Veteran
I had leaking headlight and wiper door vacum actuator relays. Headlights worked slow,... but ok. It however played havoc with the throttle response on Project Ramjet 502's FI, causing it to be very unpredictable. After a strong accelerations and then backing off the throttle I would experience a delayed engine surge. Pretty scary. Turned out the partial vacum leak caused the Fuel Injection MAP sensor to sense a lagging unstable manafold apsolute pressure. Also the fuel pressure regulator swings fuel pressure +/- 5psi based on vacum reading. Made for a wild ride 
I soaked the actuator O-ring seals in PB penetrating lubricant overnite and that seemed to have swelled them to a good seal. Its been over a month now and still has a good seal...... Anyone tried that before? how long does it last?
Bullshark
I soaked the actuator O-ring seals in PB penetrating lubricant overnite and that seemed to have swelled them to a good seal. Its been over a month now and still has a good seal...... Anyone tried that before? how long does it last?Bullshark
Drifting
Joined: Sep 2001
Posts: 1,427
Likes: 1
From: Boxford Mass
The worse thing I ever did was take a good hard look at my vacuum system because I found little leaks everywhere. My vac level bled down way too fast. Together they added up to a serious problem. One more actuator relay to change and I'm done.
The most frustrating find was a bad reserve tank. It had a slow leak. I'll have to bypass the tank for now. I'll tig that up during the hydraboost conversion this winter. I just won't be able to operate any vacuum accessories without having the car running.
The most frustrating find was a bad reserve tank. It had a slow leak. I'll have to bypass the tank for now. I'll tig that up during the hydraboost conversion this winter. I just won't be able to operate any vacuum accessories without having the car running.
Le Mans Master
Joined: Jan 2001
Posts: 6,938
Likes: 1
From: San Diego CA
I guess I'm lucky. The previous owner replaced the entire system and i can pop or close the headlights at least once with the car off. Even the winshield wiper door and wipers work flawlessly.
