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RX-7 1st Gen Specific (1979-85) RX-7 1979-85 Discussion including performance modifications and technical support sections

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Old 03-24-2009, 04:35 PM   #1
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Default Running the vent line properly?

Well i have no charcoal canister and no tip valve on the car anymore. Right now i have the vent line capped. But this is going to cause some serious vacuum issues. But where can i run the vent line? Just up somewhere? Then what you make good tip valve? Summit sells a few at around 11 dollars.






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Old 03-24-2009, 06:10 PM   #2
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I don't remember how I have mine on my FC.

Any I don't know what a 'tip' valve. Does it help to make the car not stink like gas? If so, I definitely do NOT have one!! lol
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Old 03-24-2009, 06:21 PM   #3
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in the event of a roll over, gas wont go everywhere via the vent line.
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Old 03-24-2009, 09:58 PM   #4
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No the tip valve as you call it is on the fuel feed line to the pump. The one on the vent line is the check and cut valve. It also may have rollover protection though I cant remember. The check/ cut valve must be working or you will have fuel problems. Its designed to limit pressure differential from the tank to atmosphere. If the tank gets warm and builds pressure up, it vents it. Also as you drive and the fuel level drops it lets in air so the tank pressure doesnt drop. You could route it to the air cleaner, or put some sort of mini filter on the end of it. But yes do NOT cap it off.

FWIW, when you open the fuel cap and hear a whoosh of air, that means the vent system is not functioning properly.
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Old 03-24-2009, 11:13 PM   #5
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since i dont have any of the items under there, what you you recommend? Track down a replacement cut valve?
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Old 03-25-2009, 07:08 AM   #6
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Quote:
Originally Posted by rx7carl View Post
FWIW, when you open the fuel cap and hear a whoosh of air, that means the vent system is not functioning properly.
But I like that sound.

Reminds me on the old 'Busch' commercials.

mmm beer.
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Old 03-25-2009, 08:59 AM   #7
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you are probably going to want to find a replacement cut valve.

I had problems with mine building pressure and it used to take forever to pump the gas. turned out to be the valve in backwards.

If you do not have the charcoal canister, you will probably want some kind of charcoal filter. Or maybe you can find a car with a real small canister. Charcoal is going to do the best to get rid of the gas smell.
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Old 03-25-2009, 10:13 AM   #8
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the smell doesn't bother me really. Could i just run a standard vent line up and call it a day?
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Old 03-25-2009, 10:35 AM   #9
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you really need some kind of filter or run it into the carb so you don't give the gas funes any way to ignite.
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Old 03-25-2009, 11:03 AM   #10
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i might be able to find a small charcoal canister and mount it up in the rear
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Old 03-25-2009, 11:34 AM   #11
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That would probably work fine if you can mount is so it is higher than the tank.
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Old 03-25-2009, 09:45 PM   #12
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Quote:
Originally Posted by Low Impedance View Post
since i dont have any of the items under there, what you you recommend? Track down a replacement cut valve?
So your valve and stuff is gone? You could try to find a replacement. One simple idea is to drill a small hole in your gas cap to act as a vent. Then cap the vent port at the tank. That whole system is really just made to comply with EPA pollution standards. Older cars just had vented gas caps.



Quote:
Originally Posted by djmtsu View Post
But I like that sound.

Reminds me on the old 'Busch' commercials.

mmm beer.
:beer:
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Old 04-03-2009, 04:00 PM   #13
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think im going to just drill the gas cap and see how it works out.
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Old 04-24-2009, 11:01 PM   #14
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Most guys that ditch the charcoal cansiter run the vent from the tank to the air cleaner, or put a small filter on the end of the line. I've also seen guys run them open with no problems, but I haven't seen them roll over either!
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Old 04-25-2009, 12:06 AM   #15
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drilled gas cap has been working quite well!
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