Vacuum Lines

[roadking77]

Trying to get my head around the vaccum lines for my 79 400 4 sp. I have diagrams, and read through a post on here from Nuc Envoy. I am looking for the 'ports/switches' or what ever they may be called. I have found something at napa, but they come in a variety with various temperature degrees. How do I know what is what?

[wheels78ta]

Are you talking about the ported vacuum switch that sits at the front of the manifold?

Part #3039491.......EFE & EGR TVV (TVS).  120 degrees.  4 ports.

[roadking77]

Perfect

[5th T/A]

I completely understand on a high end restoration why someone goes to all the trouble to duplicate what the factory originally did. That is a great drawing from Wheels, better than the tiny one  located on the  emission sticker the factory puts on the top of the core support. But, It does give me a vacuum line headache!

[wheels78ta]

Now the bad news...........The correct ported switch #3039491 is very hard to find.  And can be expensive.  $200-$400.

Be careful when searching.  There are places that will try to sell you #3040871.  It is intended for the 301 and 151.  It is set for 150 degrees.

All this means is when the temperature is met......a port would open to send vacuum to that line or a port would close etc.

[Wallington]

Apart from a high-end resto where the typical guy couldn't tell the difference, all it does is fine-tune the EGR vacuum and source, from manifold to ported based on temp as it warms up. Tuning guys testing for emissions might be able to check, not many others would know. Many don't have EGR hooked-up, or is in place but isolated, simply for looks.

Here's a list of possible alternatives, may not workl exactly the same, may need blue paint!

GM   3039491
STANDA...   PVS111
ACDelco   212-27
AIRTEX   7P1023
ECHLIN   2-1181
STANDA...   PVS107
GM   3033795

[roadking77]

I have before and will admit again, I know nothing about mechanicals. I have been trying to get my head wrapped around vacuum. Frankly, it may as well be like me trying to read chinese, same result. The diagram shown is def. much better than the emission sticker. Brian H was kind enough to send me a 78 manual, I have a 77 and an 80 as well as the 79 supplement. It is a big help. Dale, the guy that built both of my motors-the 79 400 manual, and the 77 400 auto- has done a pretty good job. My 77 runs fantastic, always starts with a couple of pumps, no matter what time of year or how long it sits. He has a conglomeration of vacuum lines all over the place. He said I could duplicate what is there on the 79. What I have now (79 motor) is a couple of jumpers so to speak that he hooked up to run the motor on the test stand and to break it in.
SO, my thought was, IF it runs like this WHY do I need to run a mile of vacuum lines? Or will it negatively effect the timing curve? I do think I need to at least run something to the distributor.

I can easily copy, but need to find the right switches now. Dale also said if a port is not needed i.e. I have at least one that goes to the auto transmission, that I can just cap that one. Makes sense to me. I had no idea but found the switches have different temperature ratings. The manual spells those out, so I may be able to figure that part.

In regards to the Delco 3039491, I did search for that. GM parts direct states that it is no longer available. Digging a bit more I found where someone said that 'Standard Automotive PVS-80' is a great substitute. Summit has that part for around $30 (yes it will need to be painted blue to look correct). Summit also has a plethora of switches, knowing what temps I need I think I can get what I want?

I will keep plugging along hopefully someday will have a running motor!

[5th T/A]

My opinion only, unless you live somewhere that scrutinizes all original emission devices including a catalytic converter are functioning, you don’t need most the vacuum lines. The other reason would be a 100% correct restoration. Unless the shaker and air cleaner are removed, it would be hard to tell if all lines are in place.

The switch that goes to the water passage on the intake can be replaced with a pipe plug. At cars shows it is not unusual to see the switches installed, but no vacuum lines connected.

What do you need? The power brake booster, vacuum advance for distributor (it will run without, but better with), vacuum line to heater controls and a PCV valve.

The EFE on the exhaust manifold and the flapper that ducts heat from the drivers side exhaust manifold can help drivability in frigid temperatures. But you probably don’t have all those pieces anyway.

[roadking77]

Thanks Larry, that is what I kinda figured the more I thought about it. I did find the switch that goes into the air cleaner  body, and will most likely put in what you have pointed out. At one point I was going for a point judged car, I have enough deviation in the engine comp. to question that goal at this point. I have a buddy that is restoring his car to 'perfection'. I have been asking him for some guidance with the lines as well. His are run 'correctly' but he did tell me most are plugged and non functioning. I am starting to get a comfort level with these enough to start ordering some parts and putting things together.

[wheels78ta]

My plans for the Y88 and vacuum lines........All will be hooked up to look like they are in operation.  I will plug any vacuum lines that are not needed to run on the final tune.  In the long run it will look like it came from the factory.

Looks like me and you, roadking77, are close to getting things running very soon.  You have the advantage with your motor on site.  I should see my motor in a couple of months.  I won't have the body work done until spring but the engine will go in first.

Just keep plugging away.  Can't wait see your finished project.

[roadking77]

If I was a betting man I would put my money on you, LOL.
Fortunately, the body is done. I have most of the interior stuff so once the motor gets running I hope to get things buttoned up pretty quickly. Looking forward to your progress as well.