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Hello Corvette Forum. I'm hoping you guys can help me like always. In my 78 Corvette I bought about a year ago it had no engine/transmission. I got a 350 small block from a different car (not Corvette) and a 700r4 that I put in.
One of the many things left on my list to do are the headlights. They do not go up or down. They turn on and I have lights, just the vacuum system has got me in trouble.
My engine does not have this part, the Vacuum Relay:
I took a look at this diagram from Wilcox and the system does not seem all that difficult to work on.
My questions are:
1. It looks as if I need two vacuum relays. Is this correct? One for each headlight?
2. Okay if I need two, where/how do I mount these to the engine? Could someone provide me a picture of theirs?
3. If I follow this routing EXACTLY to the tee. My headlights will finally go up and down?
1. Yes, you need two.
2. They do not mount on the engine. Have you looked in the area of the headlights near the actuators, which is where they are mounted.
3. In theory, yes.
1. Yes, you need two.
2. They do not mount on the engine. Have you looked in the area of the headlights near the actuators, which is where they are mounted.
3. In theory, yes.
Ah okay, I would often see pictures of what I thought were these mounted on the engine. I dont know what I must've been looking at. But thank you for the help. I will check by the headlights to see what I've got and hopefully can knock these headlights out. Thanks man
Hello Corvette Forum. I'm hoping you guys can help me like always. In my 78 Corvette I bought about a year ago it had no engine/transmission. I got a 350 small block from a different car (not Corvette) and a 700r4 that I put in.
One of the many things left on my list to do are the headlights. They do not go up or down. They turn on and I have lights, just the vacuum system has got me in trouble.
My engine does not have this part, the Vacuum Relay:
I took a look at this diagram from Wilcox and the system does not seem all that difficult to work on.
My questions are:
1. It looks as if I need two vacuum relays. Is this correct? One for each headlight?
2. Okay if I need two, where/how do I mount these to the engine? Could someone provide me a picture of theirs?
3. If I follow this routing EXACTLY to the tee. My headlights will finally go up and down?
Thanks for the help all!
The relays go up front, under the nose....between the headlight doors.
Yes if you route everything as it should be routed....it will work...assuming:
1) The Headlight switch is operating properly.
2) The reservoir tank hold vacuum.
3) The relays function properly.
4) The headlight override under the column is functioning properly.
I do not recommend the cheap relays available for $40 a pair.....
They work just OK. I have gotten one recently brand new that leaked across the three ports.
A few things.....the center port of the relay is the vaccum feed from the tank. The headlight switch and override switch CUT vacuum to make the relays function to make the lights go up. Vacuum to the relays make them go down.
Buy or borrow a Mighty-Vac and test your can and lines......
It really is a simple system...and you will have learned a ton if you make the work....you will slap yourself on the head and say "that wasn't so bad..."
I just did a 76' system that every line was rotted and relays shot as well as hoses missing......had it working in about 1.5 hours.
Jebby
Last edited by Jebbysan; Jan 21, 2016 at 02:42 PM.
Thanks Jebby. You gave me the confidence I needed! I will first make sure to check the tank and invest in some good relays. I think I will purchase all new lines as well. Just so I know the most of the system is new.
Last edited by Matty Gritt; Jan 21, 2016 at 02:54 PM.
Hi MG,
This photo is from an earlier car but will perhaps give you an idea WHERE the relays are located between the headlights AND the hoses that run from the relays to the 2 headlight actuators.
This system can be quite a puzzle since all the parts need to be working properly for the headlights to raise and lower.
Getting all the pieces and hoses in place is the first step. Some times NEW parts aren't the best quality so aren't always the answer.
Good Luck!
Regards,
Alan
I have a video on how the parts can be tested, so why not test the items you have before you purchase parts you don't need.
The video will show you how to test each item. You'll need a mityvac pump for sure.
You can test the actuators by starting with the backside. If they hold vacuum on the backside then you probably need a new seal and dust boot on the front to fix it. If it doesn't hold vacuum on the backside then you need an actuator.
Here is the video that will help you test the other items in the system.
Need Help Tackling my Headlights
