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Discussion Starter #1
build 1723.
I am looking for a locking vented gas cap for my Cobra. The current one is non-vented. It is made by Stant.
The problem I am having is when I remove the cap there is a lot of pressure under it. The gas tank is the upgraded aluminum with external pump. There is a vent tube from the top of the tank to just below the gas cap on the fill tube. I have tried Stant 10492 (G-92) which didn't work because there is a stop plate of metal which wont allow the cap to go deep enough into receiver hole and the gasket is different. The cap that's in my car measures:
1.33" neck diameter, 2-5/8" total diameter, 1-1/2" from bottom lip of cap to bottom of cap.
I don't care what cap I use as long as it fits and is locking and vented.
Any help would be appreciated.
Frank
 

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Just drill a very small hole in the cap. That's what I did.
 

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I don't like a locking cap, so I switched to the Toyota cap. I used the smallest drill bit I had, and drilled under the handle.



 

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NAPA
Part #: BK 7031043
Line: Balkamp

NAPA $12.29.
 

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Discussion Starter #7
NAPA
Part #: BK 7031043
Line: Balkamp

NAPA $12.29.
Hi Bob. Sorry I didn't get back to you sooner. After trying MANY MANY caps all of which did not fit and if they did they were not vented. So I went with you solution. I purchased a Napa 703-1043. I had to modify it by bending the two longer tabs, there were four of them, so the cap would fit into the filler tube hole. Then I shortened the bolt on the lid that goes over the cap, which is spring loaded, so the lid would close. The new cap fits very tight. As to the hole that I drilled in the cap. The drill went in give or take 1/4". Is that enough or should I go deeper?
Thanks for all of your help.
Frank
 

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On the bottom of the cap there's a plastic vent cover. I made sure to drill into that space, but not through the plastic cover.
 

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Hi Bob. Well, I took a drill and tried to go thru the white piece of plastic in the bottom of the cap and all it did was to spin the plastic so I didn't go any further with the drill. I also drilled a small hole in the top. I had to bend the two tabs on the bottom so they were pointing down and not hitting the opening of the fill pipe. I put it on the car and went for a drive. When I got home I removed the cap and the pressure was still there. I must be doing something wrong. Attached are some pictures of the cap. Any Ideas.
 

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Mine looks slightly different than yours.


I started at the top, and drilled all the way through the cap, but not through that Yellow plastic bit. I could see the end of the drill bit through the holes in the plastic.


If yours is not venting, then you probably didn't drill all the way through

Just now, I took mine apart. I should have done this before, but I got lucky. There's only two small tabs that are bend inward to hold everything together. Be careful those small parts are under spring pressure. The cap is designed to allow air to go IN to the tank, but not out. That prevents a vacuum, which would prevent fuel flow.

Once you take it apart, you can see the rubber diaphragm. Make sure you drill a small hole in that. Doesn't need much of a hole. If you can see through it, it's big enough.


The rubber diaphragm is the third item from the right. Just to see what would happen, I put it back together without the diaphragm.
 
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Discussion Starter #11
Hi Bob.
Well I finally got to do some more work on the cap and finally the rain let up. You are correct my cap is different than yours. Where you have a yellow removable bottom piece that holds in the springs and washers. Mine is metal and you can't remove it. So I drilled deeper from the top of the cap and past the plastic or rubber washer hitting what looked like the inside of the bottom piece that holds in the other parts then took a ride. It didn't work. After pushing the springs from the bottom of the cap I discovered there was another metal washer between the plastic or rubber washer and the inside of the spring housing. So I drilled that washer being careful not to go into the metal housing and guess what. NO MORE BACK PRESSURE.
Thanks Bob for all your help.
Frank
 
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