Well, now that the motor works it time to fix the hundreds of small things starting with my headlights. Can some one explain the basic operation of the fail safe and vacuum op? My head lights did not come up the other night after turning them on with the switch AND then pulling both "fail safe" vacuum release levers by my knees. I assumed they were designed to relase vacuum and hense let the springs pull the lights up. BTW my entire aux vacuum system is currently not connected to the manifold due to a least one leak (I bet 10 leaks LOL).

Ok guys thanks and let the comments rip!!!!!!

 

Vacuum is needed to both open and close the head lights. A supply of vacuum is stored in the tank in the nose of the car. The **** by your knees is not a fail safe, but and over ride to keep the headlights open when you turn the switch off, for cleaning or maint.

There are several places where you may have a vacuum leak. Most common are the seals on the actuators (the parts that open the headlights) or the vacuum lines them self.

Good luck.

 

The two switches under your knees: One of them raises and lowers the headlights if the headlights are turned off. The other one opens and closes the wiper door. The actuator right behind the headlights ( looks like.... what does it look like? A can with a rod sticking out of it?) uses vacuum to open and close the headlights. The springs just stabilize it, and I guess they keep the headlights in place, whether they are opened or closed. MJ

 

If you really want this to work reliably, you need to replace the ac hoses (Dr. Rebuild has a nice set with diagram) and actuators. Actuators can be repaired with baby bottle nipples, but with a 30 year old car, I suggest biting the bullet and buying new ones.
Also make sure the primary vacuum line filter and one way valve are replaced to insure a good source of vacuum.

 

Another source of issue with our headlight system is the control actuators. These control whether the vacumn goes to the "Up or Down" side of the headlight actuators as discussed above. If the diaphrams are shot in these, you will have a leak and your headlights will open slowly, at different times, or not at all. These little jewels are around $75.00 each, but are real easy to replace. Use a set of vice grips to squeeze the hoses and a vacumn gauge to track where your leak issues are. Install the vacumn gauge in the supply line to the tank, and just follow the hoses through each componet squeezing shut the hose and watching the gauge, and you will find where the leak is without buying every part in the system. :yesnod:

 

This may help you alot. Its a simple diagram of the system.

http://www.stingray.nu/bilder/vacuum.pdf

Also a step by step guide that may be worth checking out. At least there are pics :cheers:

http://www.zip-corvette.com/has2.htm


[Modified by flood, 2:37 PM 4/16/2002]

 

OK, down to the basics...both the wiper door and the headlights are controlled by vacuum relays....as such they have a small hose as the controll hose, one large source hose going to the engine, through a vacuum valve, shared with the small hose circuit....now in this large hose circuit is a vacuum storage device...simply a large coffee can under the nose of a later shark...you being a '71 like my '72 have a squareish looking 'pillow' shaped steel canister under the master cylinder, on the fender liner....it's a common failure item...
now the way the system works is....the vacuum relays are a spring loaded device, the small controll hose is set to that either system is in the suck down position...in other words IF the input signal has vacuum, the relay goes to the position so that the vacuum motor/canister goes to the down position...
if the spring loaded relay changes state it passes large hose source vacuum to the other side of the canister, changine state and raising the doors...

so having said that you need check for plenty of vacuum at the SOURCE hose, this is the large hose into the middle of the 3 hose row on the vacuum relay...
the other two hoses go to the up and down side of the vacuum canisters/actuators/motors...wheatever....

so to check for proper operation, you need vacuum at the controll input, vacuum at the main power (large hose input) and then go from there....

no question these systems are a bitch to fix....but if you can just apply elementary elecrical theory to this vacuum sh it you will have it made....
takes a bit of thought though...;-)))

 

Ok so if I get this right you guys seem to be saying that the springs in the head light assembly are for stableization and not used as part of a "fail safe" in a loss of vacuum situation. I assumed that in a case where the vacuum control fails at night (head lamps down position)...one should release vacuum as amanual overide under the dash (left or right pull down valve) and same for the wiper door. If this IS the case mine are in the stuck down mode no matter what!!!! And this system was working a month ago!

Comments welcome!!!!!

Oh and thanks all for the previous comments and sugestions keep em comming I eat this poopie (as all us Vette junkies do! Its a sickness LOL)

 

poopie? I did not write that!!!

I said "We all eat the SHIXT up"!!!!!! Sheesh political corectness to this degree is a little scarry!!!!!!!! Next thing you know they will not let you say HOOKER HEADERS or VALVE JOB......... :mad