Vacuum Control Valve (VCV) and harness - '81 F-100 I6

[rthenry145]

My guess would be: S - Signal, E - EGR valve, M - Manifold, D - Distributor. The issue comes in what the valve was originally used on, so the letters may or may not be of any value.

So my carb is missing the WOT.

I have the DIST running to what I think is the Carb "S" port.

So I was going to use the VCV "D" to run to the Purge CV.

Cap off the VCV "M" and Carb "3".

Run the VCV "E" to the EGR if I can get a WOT hooked up otherwise cap VCV "E" as well.

Run the VCV "S" to the Carb "E".

how crazy is that ?

[Gary Lewis]

No Sir, Not a full on restore, I want it running right of course and will gladly tinker her and there as some thing have already disappeared like the SMOG / AIR PUMP system, which I assume was on it when new. It's seen a lot of mechanics from a lot of locations over the years, lol ! I will have questions to understand just what I can safely tinker with, i.e. use intake manifold vacuum instead VCV if possible. What ports can be plugged on my cart YFA 1bl, etc ... I'm a bit OCD and sometimes want to understand it more than anything so I can make minor changes as they prsent themselves.

For example my CARB is missing the WOT so I know this is an issue with getting the EGR working correctly. It's been suggested to just cap off the EGR tube and also plate the exhaust /gas ports too.

If you aren't going for a full restoration, and especially if you don't have the AIR pump, then I'd simplify things, as I've outlined here: Underhood/Vacuum Systems.

As for connections to the carb, the YFA's I've been around, like David's, don't have full manifold vacuum on a port. In other words, the port that his has does not have vacuum at idle, which is the way I like to plumb the vacuum advance on the distributor, but doesn't get very high at large throttle openings. So you are stuck either running manifold vacuum or the weak vacuum from the carb.

[Gary Lewis]

"David - Would you check to see if I have all of those captured here: Underhood/Vacuum Systems/Vacuum Diagrams."

Whew... that is not easy! The list I copied from The Ranger Station, has 62 items. Your list has 27 items.

On your list, is the following not on the list I copied: C: Choke, VRV: Vacuum Regulator Valve; TVS: Thermal Vacuum Switch [Throttle Valve Solenoid on my copied list] and V: Vent.

David - Thanks. Didn't realize that mine was so short. But, maybe the Bullnose trucks didn't use all of those?

[1986F150Six]

David - Thanks. Didn't realize that mine was so short. But, maybe the Bullnose trucks didn't use all of those?

 

I suspect that is correct. I don't know the range of years covered by the list I copied.

[rthenry145]

David - Thanks. Didn't realize that mine was so short. But, maybe the Bullnose trucks didn't use all of those?

 

I suspect that is correct. I don't know the range of years covered by the list I copied.

First off, I must say again thanks for all the help! I believe I got it all hooked up and she's ( my wife calls her Betsy) running better than I expected for a novice like myself. Apparently, I got some vacuum leaks resolved as several areas improved that I can only assume are related such as the transmission is much smoother when shifting from park to reverse or drive, rpm idles down on its own after a short period after cold start. I replaced the VCV, PCV, oil breather cap, air and oil breather filters in the air cleaner, as well as the BI-MET valve and CWM modulator in the air cleaner. Replaced the Diverter (motor) valve on the air cleaner snout and added a new flex hose from the snout down to newly installed heat shroud on the manifold!

Replaced the 2 charcoal canisters and purge CV valve while I was at it...

Hooked up a line from the fresh air intake on the carb to the metal tube that passes through a round slot on the intake manifold and is hooked to the other side of my carb.

Of course new vacuum hoses ( or fuel hose if I couldn't find the right ID vacuum hose) all around!

Can anyone shed some light on what the port with a blue cap on the drivers side of the carb is for?

All in all, not a bad 3-4 Saturdays! Now, on to another topic as I may have a bit of blowby from the oil breather and oil dipstick tube! HAHA, always something else to do!

 

[Gary Lewis]

First off, I must say again thanks for all the help! I believe I got it all hooked up and she's ( my wife calls her Betsy) running better than I expected for a novice like myself. Apparently, I got some vacuum leaks resolved as several areas improved that I can only assume are related such as the transmission is much smoother when shifting from park to reverse or drive, rpm idles down on its own after a short period after cold start. I replaced the VCV, PCV, oil breather cap, air and oil breather filters in the air cleaner, as well as the BI-MET valve and CWM modulator in the air cleaner. Replaced the Diverter (motor) valve on the air cleaner snout and added a new flex hose from the snout down to newly installed heat shroud on the manifold!

Replaced the 2 charcoal canisters and purge CV valve while I was at it...

Hooked up a line from the fresh air intake on the carb to the metal tube that passes through a round slot on the intake manifold and is hooked to the other side of my carb.

Of course new vacuum hoses ( or fuel hose if I couldn't find the right ID vacuum hose) all around!

Can anyone shed some light on what the port with a blue cap on the drivers side of the carb is for?

All in all, not a bad 3-4 Saturdays! Now, on to another topic as I may have a bit of blowby from the oil breather and oil dipstick tube! HAHA, always something else to do!

Good job! That carb looks great, and with it running that well you must have nailed it.

As for the vacuum port, not all installations used all of the ports. I can't quite tell from its placement if that port is port vacuum, meaning that it doesn't have vacuum at idle, or is manifold vacuum, meaning it does have vacuum at idle. And the only reason to ask that question is if you have vacuum connections you aren't sure of. Otherwise, don't worry about it.

Having said that, you shouldn't have oil fumes from the dip stick tube or the breather. All of that should be pulled through the PCV valve unless you have a whole lot of blowby. So check to see that the PCV valve is working properly, which you can do by pulling the PCV valve from the valve cover and see that it has a really strong vacuum on the bottom of it.