some genral new questions

[new owner of 75]

I'll start my saying I've resorted 2 ol 68 mustangs , 1 coupe and a gt convert. and am well seasoned on the 2 of those. But I'm tickled to say now I have the corvette itch and i can't stop itching it! Can someone tell me about the 2 valves under the driver side dash, i know there headlight controls and the lights come up and down most of the time but now 1 is stuck and i don't know the correct opperations of the 2 valves? Also my new car sat in a barn since 1981 and just pulled out in the new world 3 days ago and i drove it home! how exciting but again what is the correct operation of the security system i put the key in , turned it to the right and the car start beeping and wont stop until i turn it back to the left, just confussed on how to set it / operated it . any new help or facts about my 75 would be great thanks

 

[6880 Mike]

One of the valves is the headlight override which allows you to open and close the headlight doors without the engine running. Not sure what the second one is on a '75. It would be the wiper door override on the 68-72 cars.

Order a reproduction owner's manual for your '75. Lots of valuable information in the owner's manual. If you intend to do most of your own work, you will want the assembly instruction manual (AIM) and the GM chassis and service manual.

A Chilton or Haynes tune up manual is also handy, but these are generic and will not provide the kind of detailed information you will find in the chassis and service manual.

 

[Bolisk]

I second the above.

 

[Vettehead Mikey]

The second valve is not a valve. It's the odometer reset cable.

 

[LVMYVT76]

RIGHT, and I think you push up on it and turn to reset.

 

[wood8835th]

If the hood is open when you turn the key on the alarm switch it will alarm. The alarm activates when the hood or either door is opened after the alarm is activated (like when you turn the key to the right).

 

[new owner of 75]

so i have a problem if when i turn the key it starts beeping right away even with hood and both doors closed?

 

[Vettehead Mikey]

Means that one of the three alarm switches is making ground, or the alarm relay is stuck. Probably the first one.

 

[new owner of 75]

Means that one of the three alarm switches is making ground, or the alarm relay is stuck. Probably the first one.

thanks for the help guys

 

[new owner of 75]

well wish me luck! going to put a new clutch in the orange flame, also going to do some investagn in transmis, don't really like the sound it's making under coast throttle. might just be low on oil but well see.

 

[new owner of 75]

so can anyone tell me if there is a fuse relay on fuel gauge? . got a full tank and gauge is ready 1/4 tank. am i going to have to replace the ??? thanks for any ifo

 

[black_81_vette]

Sounds like a stuck sending unit or the float is garbage.Get under it with a rubber mallet and rap the tank it might come loose.Also you may want to drop the spare tire carrier to gain better access.

 

[fm1]

One of the valves is the headlight override which allows you to open and close the headlight doors without the engine running.

I don't mean to hijack this thread, but I am slightly confused here. The valve for the headlight door override on my '80 opens the headlight doors without the headlights being on, but the car does need to be running. Once the engine is shut off, the doors will stay open with the lights off. When the car is once again started the doors will stay up until the valve is closed.

If the engine isn't running and the car is off, pulling this valve open does nothing. Is this right ?

My headlight doors work fine but I do use this valve to keep the headlights up when I wash the car.

 

[Vettehead Mikey]

If the engine isn't running and the car is off, pulling this valve open does nothing. Is this right ?

It's not right, but it's very typical of an unrestored C3. For the headlights to raise or lower when the engine is not running, there would have to be a source (reserve) of vacuum. C3s have a reserve tank somewhere under the hood for this purpose.

When new, the entire vacuum system was 'air tight' and the reserve would be sufficient in volume to raise and lower the lights at least one cycle, hours or days after the engine was shutdown.

30+ years later, very few cars have a 100% perfect system so any leak anywhere will prevent keeping sufficient vacuum for than a few minutes or so. In other words, most cars leak but the owners don't know, don't care or (like me) will get around to finding the leak(s) some day.

 

[fm1]

Ah ha ! Now I understand. I think I will try opening the valve a few minutes after the car is shut off and see if there is enough vacuum reserve for it to function properly. The owners manual doesn't say wheather or not the engine needs to be running for this to work, but it lead me to believe that it didn't have to be running, which is why I asked the question. I think I will test it now.... I'll post back up in a few minutes....

 

[fm1]

In other words, most cars leak but the owners don't know, don't care or (like me) will get around to finding the leak(s) some day.

Looks like I am with this same school of thought !

After the car ran for a couple of minutes, I opened the valve with the car running and the doors operated properly, I also operated the doors by turning on the headlights by the headlight switch and they also worked properly. I then let the car run for about 2 more minutes, let it idle out, and turned the engine off. After about 30 seconds with the engine off, I opened the valve. The doors did not work. Like you said, someday I will get around to finding the reserve leak, someday. Thanks for the info & insight !
Too bad its raining here....got the itch to take it for a cruise, sitting in it in the garage while its running is a tease.

 

[fm1]

OP - hope you can use this info towards your restoration, sorry if it pulled your thread a little off base. Enjoy your C3 !