Distributor vent/air locations? (1 Viewer)

[woytovich]

I just (finally) reinstalled the VCV and hoses for the distributor ventilation system. Unfortunately my 40 does not have a port on the firewall to draw air from the cabin nor does my air cleaner have ports for connecting up air lines for the vac system. (I do not know the vintage of my air cleaner assembly).

Any solutions out there other than adding the cabin port and either replacing the air cleaner assemble or tapping it for ports? Do both of the lines from the VCV mentioned above just need access to clean air? Would it be enough to add a filter to the end of those lines and mount it high up in the engine bay?

Mark

 

[Solace in Solitude]

It’s easy to tap a port on the AC, for clean air.

But, all you need is clean, filtered air... just run a hose, from the dissy, to the PS side of the radiator, and add a small filter to the end of it.

As long as you are pulling vacuum, from the dissy, either method will evacuate the dissy.

 

[thebigredrocker]

Sounds like one side needs a bit of vacuum.

 

[woytovich]

Yes, I have the VCV vac side hooked up to intake manifold vacuum that will open the port on the VCV properly (it is a working VCV). It is the fresh air ports that are in question.

 

[woytovich]

 

[woytovich]

I confused... can someone clarify the path(s) of air and vac?

 

[woytovich]

 

[woytovich]

This seems to confirm the hand drawn diagram... the FSM diagram seems to show Y and X connected together to the dissy rather than Z and X

Still want to understand the air flow logic.... @FJ40Jim ?

 

[Solace in Solitude]

With my install of a DUI, I no longer have and if this connected... except vacuum to dissy vac adv.

But, your FSM diagram shows

S to gas filter
Z to dissy
X & Y to the AC

Your drawing shows differently

S to gas filter
Z & X to dissy
Y to AC

I don’t understand why you aren’t just following the FSM...

... and why you have vac adv capped in the dissy vac adv module... why not pull vacuum?

 

[samatulich]

This is how I understand the vented distributor cap working:
If you have a water proof dizzy, then you want to draw air through the dizzy cap. You are trying to prevent moisture from accumlating inside the distributor. When the dizzy is firing, it creates heat, when the air heats up it expands inside the distributor cap, when the air cools, it will draw in cool moist air from the atmosphere(humidity).
The cap should have two ports. One will be vented to the atmosphere(inside the cabin or engine bay) should have filter attached, the other should then be routed to the air cleaner housing. The vacuum created by the intake will draw air from the filter, through the distributor cap, into the air cleaner housing. This will keep fresh air circulating through the distributor as the vehicle is running. Helping to creat a dry environment for your dizzy.
By locating the air filter up the firewall or inside the cab will allow deeper water crossing.
Hope that helps.

 

[Solace in Solitude]

The dissy ventilation system evacuated moisture AND ozone from the dissy.

Ozone accumulation can destroy rubber and cause the dissy to blow up.

This is a great thread. Pay particular attention to @1911 ‘s post... the ninth or tenth post from the top.

'78 40, 2 ports on distributor cap??

 

[woytovich]

@Solace in Solitude that drawing is not mine, it was borrowed from another thread here. The FSM diagram seems to show the "loop" of vac line links Y & X when it really links X & Z... I think

@1911 it seems you have the large vs small ports on the cap reversed in the thread linked above... the large port/hose goes to the cabin clean air source.

My question remains unanswered... what is the air flow logic relating the to VCV?

Is this true:

Vac from the intake manifold opens a valve in the VCV allowing vac from the air cleaner to pull air through the dizzy from the cabin.

If this is true I want to also understand what the loop between VCV ports X & Z does.

 

[1911]

[USER=15010]@1911 it seems you have the large vs small ports on the cap reversed in the thread linked above... the large port/hose goes to the cabin clean air source.[/USER]

Could be, though I left those hoses in the same positions that they were in when I bought the truck (and was still completely smogged). Doesn't mean that some PO couldn't have swapped them. And, the diagram I posted was one that was supposedly blessed by Jim C.

My question remains unanswered... what is the air flow logic relating the to VCV?

I always thought the goal was to apply vacuum to the rotor cap/dizzy, to suck the generated ozone out, and dump the ozone-laden air into the air cleaner where it would ingested in the intake and burned. The air and ozone sucked out of the dizzy, to be replaced by clean air from the cabin.

But I don't have an answer as to the logic applied by/to each port on the VCV.

 

[Solace in Solitude]

So... you are trying to discern “internal” workings... I can’t help, I no longer have a VCV... but @Output Shaft discusses his understanding in post #12

Distributor cap vent VCV issue

 

[samatulich]

Is this true:

Vac from the intake manifold opens a valve in the VCV allowing vac from the air cleaner to pull air through the dizzy from the cabin.

If this is true I want to also understand what the loop between VCV ports X & Z does.[/QUOTE]

Perhaps X and Z are not supposed to creat a loop. Are there other ports that are plugged? Maybe one is to be hooked up to the outer port on your dizzy and give you more advanced timing at altitude or high speed?

 

[woytovich]

No, the dizzy ventilation "circuit" is not involved in the advance port's vac circuit.

 

[woytovich]

I read what @Output Shaft and what @FJ40Jim wrote... im I still thinking the FSM above us wrong in that it shows X&Y looped rather than X&Z.

And still want to understand the reason for the loop.

 

[woytovich]

I THINK the FSM diagram is showing how to TEST the VCV by blowing air into port Y to see that the path Y to Z is open only under vacuum on port S. It is NOT showing the flow of air during operation.

 

[FJ40Jim]

I can't suss out what you need to know. The important thing is that the photo in post #8 shows the correct stock hose layout for 79-87.