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Re: Vapor Separator?
[Re: 71383beep]
#280703
04/09/09 12:22 PM
04/09/09 12:22 PM
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Joined: Oct 2008
Posts: 765
Shoreline, Washington
72roadrunnergtx
super stock
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super stock
Joined: Oct 2008
Posts: 765
Shoreline, Washington
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The fuel tank vapor separator on these cars at about that time, were simply the first steps at capture and reuse evaporating unburned hydrocarbons (fuel vapors). Prior to that, automotive fuel tanks and carbs were allowed to vent openly to the atmosphere. A correctly functioning fuel tank vapor separator system is one of the so called “emissions” systems that will not adversely effect “street” performance. Can you get away without it? Sure, but you will need to provide a way for the tank to vent. If it were me I would be looking for a replacement separator and make sure all the rubber hoses were in good shape and clamped tightly.
I have seen over the years the vent line at inner fender caped off on a lot of cars, assuming the rest of tank vent system is intact, this seals off the tank altogether and could lead to fuel starvation or a possible tank collapse if the wrong filler cap is used.
Not all that familiar with the Demons but understand they are not quite as vulnerable to some of the Holley’s leaking gaskets and warped bodies. I think I would get it good and hot, shut it down, open the hood and pull the air cleaner off, wait the 30mins, see if it starts any better. Could simply be the same thing described above were bowl vapors collect in the air cleaner.
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Re: Vapor Separator?
[Re: 72roadrunnergtx]
#280707
04/09/09 09:48 PM
04/09/09 09:48 PM
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Joined: Apr 2007
Posts: 1,261
ILL
mark7171
pro stock
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pro stock
Joined: Apr 2007
Posts: 1,261
ILL
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Quote:
That diagram is from the 72’ FSM, first year for the charcoal canister. The 72’ canister had two metering orifices to control air movement through the canister back to the intake via a tee tap into the PCV line. One orifice was controlled by a diagram connected to the timed vacuum advance port. Basically at idle only the .030” orifice was in play, anything off-idle brought other .055 orifice in. It did not affect the function or timing of the vacuum advance. The vacuum line for the canister diagram was “teed” into the vacuum advance line. 73’and up canisters were of the three line design, without dual orifice and the diaphragm.
You history is correct. Just commenting on the poor performance and things-o-plenty to fail .
A vented cap would due, and not lead to TANK COLLAPSE! Strategically we need our tanks on the battle feild.
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Re: Vapor Separator?
[Re: 71383beep]
#280711
04/10/09 07:14 PM
04/10/09 07:14 PM
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Joined: Oct 2005
Posts: 9,065
Milwaukee, WI
In_The_Pink
master
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master
Joined: Oct 2005
Posts: 9,065
Milwaukee, WI
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Quote:
I was wondering if the actual separator can come apart. After 30+ years i have to imagine that something may have gotten in there and made a home or something. Hornets nest or something. If that thing is all gunked up I can imagine have problems too.
I'm going to say no, based on the '71 B-van separator I have. The bungs are welded/brazed to the bottom cap, and the entire unit is sealed.
I would try blowing compressed air through each port, capping tree and leaving one other port open. You should be able to tell quickly if or which ports are fully open as they should be. 
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