DynoDave
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Motown Mopar-Wizard
Posts: 11,257
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Post by DynoDave on Mar 30, 2018 5:32:45 GMT -5
Regarding the overfill limiting valve, it indeed is suppose to help prevent overfilling the tank. It is closed during tank fill up as the head of fuel reaches the top of the tank. Afterwards, during thermal expansion, the expansion and vapor pressures are enough to open it to allow the vapors to go to the charcoal canister. I think I will keep looking for this elusive valve. Now you have ME curious too. Any idea where this component mounted, or what it looked like? |
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Deleted
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Post by Deleted on Apr 6, 2018 12:14:40 GMT -5
Not really. Since you have a 72 Rallye, maybe you have it? Do you still have your canister and vent lines and all? Seems like it was maybe just a little bulge built in to the vent line up in the front (verticle part of the steel line), just before the upper vent hose goes to the canister. In the bulge is where this valve is? Maybe I am imagining that. I just find it so curious that nobody knows what it is even though it's in the FSM. There's a guy in the Toledo area that has a 72 SE that comes to shows. And another guy I see often with a 73. I'll try and grill them. I imagine the same system would be on a 72 Satelite, or any other 72 mopar.
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DynoDave
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Motown Mopar-Wizard
Posts: 11,257
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Post by DynoDave on Apr 6, 2018 12:30:51 GMT -5
Confession time...most of my car is in another state. Some parts are here. Some parts, I'm sure, are missing. I bought it completely disassembled. Never again.
It does not currently have a canister on the body, or among the boxes of parts. Nor lines going there that I can recall. But a previous owner was going Pro Street with it, back when that was all the rage. So he discarded MANY non-essential parts.
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setauketjeff
Settling In
1971 440 MGM Every stoplight is a staging light!
Posts: 230 
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Post by setauketjeff on Apr 9, 2018 14:00:43 GMT -5
Here's what I did on my 71 (see below): Installed a valve cover breather cap that I could insert a PCV valve into and run to the Air Cleaner in-take nipple to get negative vacuum. The carburetor overflow/vent line then runs directly into the vapor return tube. Since I have a 440HP, I will soon add the proper metal fuel lines, with the metal vented gas filter / separator, and run the gas filter vapor line back to the vapor return tube and connect using a T connector. Not original, but should serve the same purpose (what do you think Dyno? I made the changes and put 100+ miles on without any oil ending up in the Air Breather. The Mopar valve covers do have baffles under the oil fill).  |
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setauketjeff
Settling In
1971 440 MGM Every stoplight is a staging light!
Posts: 230
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Post by setauketjeff on Apr 9, 2018 14:09:35 GMT -5
BTW,  totally with not forcing too much fuel in the tanks, especially when the filler neck is so low. Agreed that you shouldn't force or "top off", but, you shouldn't leave your tank half empty either. Especially in climates where you will get condensation in the gas tank. And now we can debate the pros and cons of gas additives like, "Dry Gas" (choose your brand name). |
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DynoDave
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Motown Mopar-Wizard
Posts: 11,257
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Post by DynoDave on Apr 9, 2018 15:00:13 GMT -5
That's an interesting breather...I've never seen one like that. Usually you want the PCV valve on one side of the engine, and the breather on the other. This creates cross-engine breathing through the crankcase. The breather can either be open from underneath to draw in engine compartment air, or draw air from a hose to the air cleaner. This is then pulled through the entire engine to the opposite valve cover where the PCV valve is. And it in turn feeds a hose that goes to the base of the carb. for a strong vacuum pull.
I'd have to see that breather to understand how that works....how air gets into the engine. If the center nipple on that cap is open to the PCV only, it doesn't seem like you'd have much fresh air going in, if any. And even if that nipple through the valve cover is divided in two, you would have the incoming air and vacuum pulling it back out right next to each other in the same cap, and I'm not sure how that would pick up a lot of crank case fumes. I'd also be curious to know if there's enough vacuum at that hose from the air cleaner to even open the PCV valve. Might be, I just don't know. It's spring loaded, and requires a decent signal to draw it open.
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setauketjeff
Settling In
1971 440 MGM Every stoplight is a staging light!
Posts: 230
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Post by setauketjeff on Apr 9, 2018 15:32:32 GMT -5
The other side (Valve Cover) has the "Mushroom" breather with the air baffle holes underneath as you described. Our Mopar PCVs of this era are mostly gravity / vacuum operated with no springs.
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DynoDave
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Motown Mopar-Wizard
Posts: 11,257
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Post by DynoDave on Apr 9, 2018 17:03:12 GMT -5
Got it. Looks pretty good then.  |
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