Author Topic: Vacuum Lines on 305 Engine  (Read 10117 times)

Offline Shaker

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Vacuum Lines on 305 Engine
« on: July 17, 2016, 01:24:01 PM »
Hey,

So let's start by being Honest.... I did'nt mark my vacuum lines when I did the Head Gaskets  :'(

So now I am in the process of putting things back together. I would prefer to get all original lines connected as much as possible. Some of the lines were plugged already by the previous owner. I`m not sure what ports those plugged lines went to.

My truck is a 1986 C10 2wd, Auto, 305, 700R4, Rochester QuadraJet Carb, Headers, Dual Exhaust.

The engine is coming out in the next 6-9 Months and I do not do a whole lot of driving, So not to worried if I loose or gain any MPG.

I have the Vacuum Canister, EGR, Vacuum Advance, PCV, 2 and 4 Port Vacuum Switch, There is another Diaphragm on the left side (as if sitting in drivers seat) at the front on the carb that I`m not sure to what it is.

The diagram on the Rad support is there and I`ve tried to follow it but I`m not sure if I have the pieces it say's I need or quite understand it.  (the heads a little foggier since Afghanistan, So my apologies beforehand to any keyboard warriors out there)


Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #1 on: July 17, 2016, 01:26:05 PM »
Here are some more pictures

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #2 on: July 17, 2016, 01:28:32 PM »
and 2 more.

Hopefully these will help you help me

Cheers

Offline Burkhalter

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Re: Vacuum Lines on 305 Engine
« Reply #3 on: July 17, 2016, 06:06:48 PM »
I'm not sure about all the rest of the stuff but I think this one goes to the pcv valve, which then connects to a to a vacuum port on your carb I think.
'85 Chevy K10 361ci sm465

Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #4 on: July 17, 2016, 07:47:59 PM »
Post a full-frame pic of the emission & vacuum diagram decal on the radiator support.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #5 on: July 18, 2016, 11:28:26 AM »
Here you go bd

Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #6 on: July 18, 2016, 03:40:25 PM »
I'll respond to your question in stages, as time permits.



Some of the vacuum ports on the carburetor will be marked with an upper case letter cast into the carburetor body adjacent to the ports.  "B" should be the 5/32" manifold vacuum source located above the fuel inlet nut, "L" is the 3/8" PCV vacuum port located in the front of the throttle plate below the fuel inlet nut, and "T" is the 3/8" bowl vent exiting the fuel bowl cover.

The "J" vacuum port is the 5/32" port physically located below the fuel inlet nut, near the right (passenger side) idle mixture screw in the following image.



The short vacuum hose from the bottom port of the 2-port TVS connects directly to the carburetor "J" port.

The upper vacuum hose from the 2-port TVS connects to a vacuum "tee" that splits the vacuum signal between the EGR valve located just to the right (passenger) side of the carburetor and a second vacuum 'tee' that splits the signal again between the TCC vacuum switch located on the firewall (imaged below left) and the rightmost 5/32" purge nipple on the vapor canister (as imaged, below right).

   

Edit: corrected port ID.
« Last Edit: July 18, 2016, 09:25:52 PM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #7 on: July 18, 2016, 09:54:22 PM »
Follow along by referring to the diagram as we continue....



The device imaged below is called a "Tip-In Vacuum Switch."  It is part of the Electronic Spark Control (ESC) system.  The 'tip-in switch' monitors manifold vacuum (aka, engine load) to allow for an immediate decrease in ignition timing when the throttle is rapidly opened.  It's purpose is to help minimize cylinder detonation and associated engine damage.  The tip-in switch appears to be incorrectly plumbed on your truck.



The tip-in switch should be plumbed directly to manifold vacuum along with the thermostatic air cleaner (TAC) and the upper port of the 4-port TVS through two vacuum tees.  The fitting pictured below is the source for the manifold vacuum and is labeled "MANIF VAC SOURCE" on your vacuum diagram.



Note that there should be a small plastic check valve in the upper vacuum hose attached to the 4-port TVS.  The orientation of the check valve is important.  The "black" side of the check valve should be plumbed toward the intake manifold vacuum fitting just pictured.

The second hose down from the top of the 4-port TVS routes to the EFE (Early Fuel Evaporation) valve through a 5/32" steel pipe, adjacent to the EFE valve located at the outlet of the right exhaust manifold.  The EFE valve is basically a vacuum operated exhaust heat riser for rapid intake manifold heating and improved fuel atomization during cold weather operation.

Study the vacuum diagram carefully.  The distributor vacuum advance connects to the 4-port TVS through a black and white plastic 4-port delay valve, labeled "DISTR DELAY VALVE" on the diagram.  Again, orientation of the delay valve color coding is important.  It appears that the delay valve is correctly connected to the 4-port TVS and distributor.  However, the vacuum connection to the carburetor should be switched from the "J" port below the fuel nut to the "B" port above the fuel nut.

Are you tracking so far?  Any questions?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #8 on: July 19, 2016, 12:04:54 AM »
Hey bd

This is great, I appreciate your help.

I think I have the issues corrected. The EFE was throwing me off in the Diagram but now that you have taught me valuable knowledge.... I Believe the EFE is obsolete and I can block that off since it went with the old exhaust. (At least I hope that'll be alright)

There is no Check Valve on the on the Tip-In Switch Vacuum line. The only Check Valve I see is the one on the Trans Conv. Vac Switch, But on the Diagram that appears as it should not be there.

The DISTR DELAY VALVE has the White end on the Distributor side and Black is towards the 4 Port switch and switched the Vacuum line to the B port.

I took some more pictures since changing the lines. Here they are and I believe I am following along the right path. They are a little dark, I edited some light into them so hopefully they are clear enough.


Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #9 on: July 21, 2016, 09:23:58 AM »


The blue/black check valve is correctly connected to the TCC switch on the firewall (above). 

Cap the vacuum nipple that used to connect to the EFE (below).



There shouldn't be a check valve in the tip-in switch vacuum line, so you are okay there.

It sounds like you aren't required to have emission inspections.  Is that correct?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #10 on: July 21, 2016, 09:42:18 AM »
Awesome, I just ordered some Vacuum caps so I dont have to use screws and have hoses hanging around.

No Inspections here, They got rid of the Emissions testing a couple years ago, Thankfully because I probably wouldn't of moved here if that was the case. Just another money-sucking Gov't program lol.


I`m not sure if you can tell me what the diaphragm on the Drivers side, front end of the carb is? Sits right in front of the Throttle Linkage with a vacuum connection coming off it.

Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #11 on: July 21, 2016, 12:16:56 PM »
Throttle return control (TRC) - it manages throttle closing to idle RPM to help minimize exhaust backfire when throttle is suddenly released by the driver.  It works in conjunction with an electrically controlled solenoid and engine RPM switch.  It was used dominantly with heavy duty emission packages.  It's interesting that it isn't illustrated on the emission control label.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #12 on: July 21, 2016, 01:22:34 PM »
I`m thinking the Carb is not Original as it does not look that old. So i`m guessing that Capping the port of is okie dokie?

Online bd

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Re: Vacuum Lines on 305 Engine
« Reply #13 on: July 21, 2016, 01:40:03 PM »
Remove the TRC actuator entirely - only two screws.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Shaker

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Re: Vacuum Lines on 305 Engine
« Reply #14 on: July 30, 2016, 12:01:20 PM »
Thanks for the help bd.

I will post a picture once everything is back together. I took off the TRC as well.