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What is this for? Vacuum problem

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Old Aug 16, 2022 | 06:45 PM
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Default What is this for? Vacuum problem

Was out for a drive the other day, stopped for dinner, then it was dark so i hit the headlights on my 76 and only one came up and it was running funny. When i got home i found this part in two pieces.
I suspected a vacuum problem and found this part (see picture) in two pieces just a few inches from my carb. I dont have the stock engine anymore so not exatly sure where this came from.
It doesnt seem to have anything inside of it. Anyone know what it is or should be???

this is the part together the way it should be.

this is how i found it. there was nothing inside it, just holes.

this is the original stock picture of vacuum from assembly manual. i dont see that part

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Old Aug 16, 2022 | 07:21 PM
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Just a filter to keep crap from being sucked into the intake from the various vacuum gadgets

I don't think they were meant to be taken apart... I would have thought there should be a fine screen or something inside
M
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Old Aug 16, 2022 | 07:23 PM
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Originally Posted by 76project
Was out for a drive the other day, stopped for dinner, then it was dark so i hit the headlights on my 76 and only one came up and it was running funny. When i got home i found this part in two pieces.
I suspected a vacuum problem and found this part (see picture) in two pieces just a few inches from my carb. I dont have the stock engine anymore so not exatly sure where this came from.
It doesnt seem to have anything inside of it. Anyone know what it is or should be???

this is the part together the way it should be.

this is how i found it. there was nothing inside it, just holes.

this is the original stock picture of vacuum from assembly manual. i dont see that part
Go to the headlight(s) vacuum drawing of the Assembly manual, it's there.
It's just a filter...
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Old Aug 16, 2022 | 08:23 PM
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Thank you
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Old Aug 17, 2022 | 09:23 AM
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Old Aug 18, 2022 | 02:55 AM
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Originally Posted by 76project
Was out for a drive the other day, stopped for dinner, then it was dark so i hit the headlights on my 76 and only one came up and it was running funny. When i got home i found this part in two pieces.
I suspected a vacuum problem and found this part (see picture) in two pieces just a few inches from my carb. I dont have the stock engine anymore so not exatly sure where this came from.
It doesnt seem to have anything inside of it. Anyone know what it is or should be???

this is the part together the way it should be.

this is how i found it. there was nothing inside it, just holes.

this is the original stock picture of vacuum from assembly manual. i dont see that part
I just purchased a completely original 77 and I recognize this lite blue check valve. It may not be a check valve but that was my impression based upon where it is. It's 2am and I've already put her to bed covered but I'll take a pic and post it tomorrow. That line runs from the Ported Vacuum Switch in the thermostat housing and is labeled vacuum line E in the diagram posted. Valve definitely not shown in diagram. I know mine is correct so again I'll post pic asap tomorrow. Headlights probably not related to this unless vacuum loos in general is making light setup weak. I'm not well versed in the light vacuum system.
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Old Aug 18, 2022 | 01:37 PM
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Originally Posted by 76project
Was out for a drive the other day, stopped for dinner, then it was dark so i hit the headlights on my 76 and only one came up and it was running funny. When i got home i found this part in two pieces.
I suspected a vacuum problem and found this part (see picture) in two pieces just a few inches from my carb. I dont have the stock engine anymore so not exatly sure where this came from.
It doesnt seem to have anything inside of it. Anyone know what it is or should be???

this is the part together the way it should be.

this is how i found it. there was nothing inside it, just holes.

this is the original stock picture of vacuum from assembly manual. i dont see that part
So I was totally wrong, here's the real skinny. There's so many vacuum hoses and valves on these cars that they run together in my minds eye. Here's a pic of what I thought it was and here's pics of what it is. The line you're showing originates at the vacuum port coming from the manifold between the carb and distributor and is the beginning of the headlamp vacuum system. Obviously on my 77 the piece you have split open has two exit ports but from looking around I'm convinced this is where your line goes.



Last edited by Mike in Mobile; Aug 18, 2022 at 01:44 PM.
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Old Aug 18, 2022 | 01:52 PM
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Quick follow up. Mine splits in two, one to headlamps one to wipers
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Old Aug 18, 2022 | 02:11 PM
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There is a picture and a description of all the parts and a diagram here:

http://www.corvette-101.com/vacuum.htm
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Old Aug 19, 2022 | 08:55 AM
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Originally Posted by Mike in Mobile
So I was totally wrong, here's the real skinny. There's so many vacuum hoses and valves on these cars that they run together in my minds eye. Here's a pic of what I thought it was and here's pics of what it is. The line you're showing originates at the vacuum port coming from the manifold between the carb and distributor and is the beginning of the headlamp vacuum system. Obviously on my 77 the piece you have split open has two exit ports but from looking around I'm convinced this is where your line goes.

I know this tread is/was about the vacuum filter OP asked about but I just have to respond to the photo above.
That is not the correct placement of the spark delay (check valve) on a 1977.
I suggest you turn to pages UPC 6L Sheet 5 & 6 of the Assembly Manual for the correct placement.
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Old Aug 19, 2022 | 12:32 PM
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Originally Posted by bmotojoe
I know this tread is/was about the vacuum filter OP asked about but I just have to respond to the photo above.
That is not the correct placement of the spark delay (check valve) on a 1977.
I suggest you turn to pages UPC 6L Sheet 5 & 6 of the Assembly Manual for the correct placement.
Thanks. I was suspicious about the seemingly unnecessary break in the vacuum line. I was curious what this assembly's function was. I'm gonna by pass it as cold cranking on the Gulf Coast is not an issue.
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Old Aug 19, 2022 | 12:48 PM
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Thanks for all the info and diagrams...I'll be needing them on my project.
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