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working on different areas as parts show up, wipers, drivers dash, vacuum lines, have a question on vacuum lines
Vacuum tank has 3 ports, 1 is vacuum source, the other 2 out of the vacuum tank run to, green & yellow to each relay
Any reason to run 2 separate lines towards the front ?
I am thinking of running 1 line towards the headlights & splicing a (T) near the relays eliminating 1 line, this would mimic the line running from the over ride switch under the dash
As I see it I am just relocating a (T) down stream
Any vacuum experts see an issue with this idea ?
Guess I'll hook up the vacuum pump tomorrow to see if & how well it works
I would expect that the reason they ran two lines is either for volume (or lack of volume since it's a vacuum
The actuators need to move a certain amount of air (or vacuum) to move the lights and if you're pulling that through a smaller dia hose it takes whatever time to move that air. To move twice the amount of air through one small hose should take twice as long type of idea and larger diameter vacuum hoses become stiffer (to prevent collapse)
So in theory, if you ran a larger diameter hose it should still function as intended. Maybe the newer silicone hoses can be larger and still flexible?
I would expect that the reason they ran two lines is either for volume (or lack of volume since it's a vacuum
The actuators need to move a certain amount of air (or vacuum) to move the lights and if you're pulling that through a smaller dia hose it takes whatever time to move that air. To move twice the amount of air through one small hose should take twice as long type of idea and larger diameter vacuum hoses become stiffer (to prevent collapse)
So in theory, if you ran a larger diameter hose it should still function as intended. Maybe the newer silicone hoses can be larger and still flexible?
Anyway, that's my wild *** guess
M
If you look at the picture 1 of the line (Ts) off to go to the relay on the passenger side, I think I doing the same as that although the wiper door is only 1 valve
I'll give it a try tomorrow & see how well they operate, they are 3/8" (i think) fairly large, maybe 5/8" heater hose LOL
OK, I forgot you have a '71 with 2 relay valves. My vac tank has only 2 ports, as pictured. One port in, pulling vac from the engine, and one port out going to everywhere else. Actually, my tank is disconnected, I have converted to electric headlight and wiper doors.
Just wondering why you'd want to change from the way it was initially designed and built? What are you hoping to accomplish other than saving on the amount of hose to run?
Just wondering why you'd want to change from the way it was initially designed and built? What are you hoping to accomplish other than saving on the amount of hose to run?
Just cleaning up 1 hose = 1 hose less to route in the clips = less weight how's that, now to find good quality lightweight made in the USA inexpensive calipers = maybe I can drill lighting holes in mine.
If it works great, if not I'll keep 2 lines going forward.
As I tell everyone = it's your car do it your way, well it's my car and if I can eliminate / change 1 small item and the system works like the factory = I'm back to cleaning up the engine compartment
Why did Chevy continue to upgrade & change their products ? & look where we are today = C8s
Just cleaning up 1 hose = 1 hose less to route in the clips = less weight how's that, now to find good quality lightweight made in the USA inexpensive calipers = maybe I can drill lighting holes in mine.
If it works great, if not I'll keep 2 lines going forward.
As I tell everyone = it's your car do it your way, well it's my car and if I can eliminate / change 1 small item and the system works like the factory = I'm back to cleaning up the engine compartment
Why did Chevy continue to upgrade & change their products ? & look where we are today = C8s
I have a 71 as well-No vacuum lines or tank here...and with the extra room I added 4 more cylinders- and it even weighs less-
The 69s had only 1 vac source that ran to a vac port switch in the front. That vac port switch then fed both headlight actuators, so it can work. GM probably tried to improve the system for 70/71 so I'll assume the 2 vac source change was implemented to improve the system.
The 69s had only 1 vac source that ran to a vac port switch in the front. That vac port switch then fed both headlight actuators, so it can work. GM probably tried to improve the system for 70/71 so I'll assume the 2 vac source change was implemented to improve the system.
They didn't add another penny (relay, hose, etc) unless they had to.
M
I have a 68 and it is the same as the 69 FOR ONCE!!! Nothing on my coupe is the same as a 69, for the uninformed. Someone must have complained about how long it takes the headlight doors to come up. That is the only reason that I can see for adding the second relay and hoses. It does take a little while, but who is in a race to have their headlights pop up and turn on? Lou.
Interesting idea to revive this old thread instead of simply starting a new one.
But yes. The small line to the relays from the headlight and override switches is basically the switching line. The large line is vacuum supply to the actuators.
headlight vacuum question
although the wiper door is only 1 valve 
