Repo RS vacuum lines

[Dave69x33]

All,

Found this article on the 1968-69 Corvette headlight door opening system. The Corvette vacuum operated system is similar to the 1968-69 Camaro RS except the Corvette requires two vacuum relays! That would be a pain; I am struggling with a system that requires only one relay! The article has good tips how to test all the components in the system which are common with the Camaro.

http://www.corvette-101.com/vacuum.htm#relay

[Dave69x33]

Other than requiring two vacuum relays, the Corvette system uses a “Pull-Down Switch” which functions similar to the slider switch located on the top of the Camaro vacuum relay. Otherwise the Camaro and Corvette systems function the same.  In fact the GM headlight switch Type AC Delco D1542, GM #1995191 is listed for:
1968-77 Corvette
1968-69 Camaro RS
1968-77 Chevrolet Caprice
1968-68 Chevrolet Impala

[Dave69x33]

Tinkerr,

As I thought about the issue you are having, if this was my car I would run the car at idle, and with the headlight switch off, disconnect the green hose at the rear of each actuator (one at a time) and connect a vacuum gauge. See if you have equal vacuum in the green hoses at each actuator. It may take a few minutes for the vacuum system to build back up to whatever your normal engine vacuum produces. Reconnect the green hoses to the actuators then turn the lights on and perform the same test with the red hoses connected to the front on the actuators.

If your vacuum signal to both actuators is the same, it possible that the left actuator with the slower acting door, is leaking vacuum past the piston seal. If you have a vacuum pump, you can test the actuator opening  and closing function. This will be easier to do with the actuator off the car but removing it is not necessary. If the actuator is leaking, try capping off the other port and try to pull vacuum.

Hope you can get your RS system working. Would like to know what you find out if you
perform this test.   I am few weeks behind you doing the same work!

[Dave69x33]

One last thought - someone else earlier in this discussion suggest to inspect the T-fitting that split the red and green hose feeds from the relay to the actuators,  to verify there is no plastic mold flashing partially blocking the vacuum flow. I found a small about in my T-fitting and used a drill bit by hand to ream the IDs clean.

[firstgenaddict]

If you can get a hold of a vacuum pump put it in another room or outside the garage with a long hose running to your port off the engine. That way you can trace things without the engine running.

[Dave69x33]

All,

To follow up on the vacuum relay testing I performed, I wanted to share some picture of my original relay and the build up of debris that can get sucked up into the unit during years of use.  I used a digital microscope connected to my laptop to get the images.  The pictures show views thru the R, Y, and G vacuum ports before and after cleaning.  I blocked off the small vacuum hose connection at the slider switch on the top of the relay then sprayed foaming engine degreaser into the three vacuum ports, and into into the bottom of the relay. Any mild cleaner such as Simple Green will work. I let the cleaner soak for a few minutes then rinsed the relay with warm tap water. A considerable amount of dirt and debris flushed out of the unit.  I repeated the cleaning 2 - 3 times.  In between the cleaning cycles I used the microscope and tooth pics (both sharp and blunt ends) to wipe away the clusters of debris soften with the cleaner, kind of like arthroscopic surgery! I finished by used very low pressure compressed air to help flush out the water.

As I mentioned and showed earlier in this discussion topic, my original relay will no longer transfer a strong vacuum signal to the actuators. I assume after 50+ years of usage and wear, vacuum leaks past the control valve seal diameters.  This is unfortunate as the vacuum relay still looks very good with a little restoration touches.  NOS vacuum relays are very hard to find and they cost $450.00+!

[Dave69x33]

Pics of the middle Y port. This is the port that transfers vacuum between the upper R and lower G vacuum ports.  If clogged with debris, the RS system will respond slowly, or not at all.

[Dave69x33]

After watching a YouTube video of a person who restored a set of Corvette vacuum relays, he replaced the filter that is installed in the lower window frame of the relay.  The Camaro relays include the same window frame for a filter.  I am not sure why the Camaro vacuum relay did not receive the same filter.  I decided to add soft foam filter material in my relay.  I cut the foam to size from a large piece of foam I had on hand.

While the Camaro relays are mounted higher up in the engine bay compared to where the Corvette units are mounted, there is still a fair amount of air borne dirt and debris that gets wiped up under the hood (hence the reason for a good quality air filter to the engine).  The relay is under a constant state of vacuum so debris getting suck up into unit is always a risk.  The filter material is not very noticeable in the relay when mounted in place.

Caution: The filter material must be soft and pliable so that it does not limit the tip of the valve from fully traveling downward in the relay. 

[Tinkerr]

I wanted to give a update on the issue I was having with the headlight doors. I was using the engine for my vacuum supply(open headers). After plumbing a vacuum pump to the tank I could hear a leak at the T fitting on the green line going to the left door. Once I eliminated the leak both doors operate evenly. Hope this helps somebody.

[David K]

My restoration was done in 1994. They still look great.