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'70 AMX Vented Gas Cap
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Sonic Silver View Drop Down
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Joined: Nov/23/2011
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Points: 7949 		Post Options Post Options   Thanks (0) Thanks(0)   Quote Sonic Silver Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2013 at 3:25pm
Originally posted by whizkidder whizkidder wrote:

I've got an early '70 California car(E006673) -- no vent on the filler neck, but the original tank had a vent nipple on the tank, with the hose/line routed to the rear of the left valve cover. IIRC, the Cali vent system is covered in the TSM also, but maybe in a different paragraph.
From page 5-1 -3 1970 TSM:
 
Fuel Tank Systems (California)
 
Fuel Tank Assemblies- All Series
 
The fuel tank incorporates an integral fuel expansion tank to provide an air displacement area for normal fuel expansion. Fuel passes through small holes in the expansion tank at a given rate as fuel volume increases due to rising temperatures. The fuel level in the expansion tank changes correspondingly with the level in the fuel tank.
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Points: 11576 		Post Options Post Options   Thanks (0) Thanks(0)   Quote amx39068 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2013 at 5:16pm
I had a car with the vent tube plugged with bug mud and it sucked the bottom of the tank up until I refilled it and it oil canned back down from the weight.  The bong it made when it started to collapse while I was on a freeway sounded like I ran over a tire that hit the underside of the car.
Dan Curtis-Owner and CEO AZ AMC Restorations; Facebook: https://www.facebook.com/amcmusclecars/ & Curtis Real Estate Development
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Points: 8509 		Post Options Post Options   Thanks (0) Thanks(0)   Quote amxdreamer Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2013 at 5:48pm
Originally posted by sidewinder sidewinder wrote:

There is also a 70 version that has a vent out the top rear of the tank and vents to the left valve cover (Calif emissions) the vent line goes through a plastic can up in the rear and then there is a tube going to the valve cover. The tank is also equipped with a large plastic bladder.

Chuck Page


Man that flash sure changes the color under the car!

Tony
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Points: 385 		Post Options Post Options   Thanks (0) Thanks(0)   Quote davec1957 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/18/2014 at 6:25pm
My solution to the '70 AMX fuel tank pressure build up was to drill out the valve from the vented cap. I was careful not to drill any holes in the cap, just removed the small valve. So now it's like having a cap with a valve that's always open, so air replaces fuel as the car is driven. Performance is unchanged and I haven't had any fuel leaking out. And best of all no more "whooooooooosh" every time I remove the cap. 
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Points: 306 		Post Options Post Options   Thanks (0) Thanks(0)   Quote bvpotash1 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/18/2014 at 9:03pm
I've got a 70 with a may build date. No vent on the fill neck like my 68 had. I also drilled a very small hole in  the new "vented" gas cap. The pressure build up in the tank seemed to be extreme.  
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