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Fuel spilling out the stock gas cap...fixes?


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I read a bunch about it, and short of converting over to a newer cap/filler neck, there are no fixes.


Anyone think this may work?  Or at least help a whole lot.







Diameter is too much at 2-7/16 o.d.  But its an extremely simple design to make up out of 2"


Put it in right at the filler neck so the gas nozzle pushes it up/open.  Im thinking slide it in and hose clamp it in place from the outside.


Seen a bunch of rollover type ball/float valves, but I dont think they will work due to the horizontal angle of our filler tube.


Any other ideas?



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That is a interesting idea if you are stuck on staying with the stock setup. 


However, the Mazda fuel neck retrofit is a great mod and you can fit newer nissan caps.


And done with cheap tools you probably already have around the house.

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Gonna make my own design.  Will be better than the one pictured.


Vertical delrin flap pushed/held down by a light spring.  Seated on a small step to stop/seal it.  Inside of a 2" diameter tube.  Slide it into the filler tube and hose clamp in place.


2-3" inside the filler neck.  Pushed open by the filler nozzle.


A project I will never get to...

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I tried.  Its new.  I used a few different types of sealing surfaces, but they all leaked.


Im also being anal.  When I say "leaked", its a full tank of gas, driving like a loon, and it was a single bead going down the body.  But every trip.  Its just annoying.


I got an nos one to seal almost all the time (by stacking 2 seals), but the new repop one wont.  The metal is not strong enough to keep the compression tight.


The easier thing to do is send the nos one to get anodized.


I also have a tough time with that type of twisting motion with my thumb.  Many boxer fractures under its belt.  Even with my new cars/caps.


I just like inventing/tinkering and starting 13 projects in the middle of my 13 other projects.  You know, like the rest of us :)

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Wish it was that easy.


The surface looked flat, but I filled it, then sanded/polished it.


That made it much better, but still a bit of a weep.


Im also being hindered by the fact that I have a 2 stroke and mix the oil in the tank.  The oil helps it find its way out/hang around, instead of just evaporating.

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Rotary  :thumbup:


They should not leak, and of course they were designed not to, but many people complain about this issue.  And its not just Datsuns.  Many 50-70's cars with this simple designed cap and a damn near horizontal filler tube has/had slosh issues.


Its one of the main reasons the american cars moved the filler from the rear end of the cars, to the sides.

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