LS1 fuel tank filler neck in stock location

[CruxGNZ]

I had some time today to finally finish this. Here are some pictures to help show what I did. Fuel tank and filler are out of a '02 Camaro and my Z is a '73.

 

I was able to take the Camaro filler and push it inside the hard rubber Datsun filler. Just used a hair dryer to make the hard rubber more pliable, lubed up the Camaro filler and pushed it inside the Datsun filler. Fits perfectly. You don't even need to use a hose clamp to keep it in place. Make sure you have the filler with the little metal flapper at 12 o'clock to make filling up the car easier.

 

After some pondering, it was going to be to difficult to make the bottom of the Camaro filler line up with the fuel tank. So, I cut 1 3/8" out of the middle of the filler and welded the end back on. You can see where I welded in the picture below. After another test fitting, it was determined that the angle of the filler was not the best. I used the Mapps gas torch to heat up where the bend is and stuck a metal bar inside and tweaked the angle some. I went as far as I thought before the metal would tear or the whole thing would crimp.

 

Well, now you're left with a big hole at the bottom where the stock Datsun filler poked through the body. I just used some rubber to fill the gap and made a little hole for the Camaro filler to poke through, but seal the inside from exaust gases. All that was needed was to connect the filler neck and fuel tank. But, can you believe it, EVERYONE around here had 1" fuel rated tubing on backorder! So, I ended up with what you see cobbled together. It works, but it will get redone as soon as someone has some tubing longer than 1 foot lengths. I also need to find some stainless steel springs to place inside the tubing to keep them from collapsing.

 

And here it would look factory, if I used the stock Datsun filler cap, BUT Garrett was kind enough to give me this one you see. I guess only three of these were CNC'd out of billit aluminum. Fits perfectly and looks pretty cool.

[Bartman]

I did something similar, but my LS1 filler neck sticks up out the top of the Datsun cap. I think I will cut the neck down like you did so I can use the Datsun cap.

[jeromio]

That filler cap looks sharp.

 

I wish there was another way to route the filler hose to the FBody inlet. I used a 2nd gen Maxima filler since its angles seemed to line up well with the S30 openings. But it's still less than ideal. The "old" S30 filler was big and wide and you could easily get the filler nozzle in it, despite the fact that the filler is almost horizontal and has body-work right above it. With the modern, narrow filler, it's tough to get the filler nozzle in there - especially since most have that big shroud that's supposed to cover your filler and block excess fumes.

 

And then the filler tube has to make this immediate harsh 90* bend, such that the tube is almost horizontal. Then there's another sharp bend into the tank inlet. I have to slow the flow to keep the auto-off of the gaspump from triggering. I think running vent lines from the filler neck back to the tank would help with that.

 

But with the wheel house right there, I don't see many alternatives for routing. For instance, I'd like to seal up the stock filler door and create a new one up higher and forward more - but where would the tube route?

[CruxGNZ]

Yeah, you couldn't move it more than three inches forward before you hit the wheel well. Even then, it won't be lined up very well.

 

Were you thinking of making a gas cap like Dan Juday has on his Z?

[jeromio]

Yes, except I want to use one of the flush mount type.

[Dan Juday]

... I have to slow the flow to keep the auto-off of the gas pump from triggering. I think running vent lines from the filler neck back to the tank would help with that. ...

 

Yes it will. I had the same problem. Real embarrassing when people are staring at your car and the pump pukes up raw gas all over your big blue fender.

 

I used an existing top vent the Suzuki tank had in it already. It's small, like 3/16". The bigger the better. And try to run it on a steady grade back to the tank without any droops in it. If I fill up on a grade with the right side of the car lower than the left the vent line gets a slug of liquid fuel in that droop and basically plugs it. I know this because it pukes up again like it did before I ran the vent line.

 

Also, try and mount the other end of the vent line as high up as possible on your filler tube. You want to make sure it is at least above the end of the pump nozzle when you're filling.

[jeromio]

I suppose re-installing the datsun expansion tank up there would also help. This is partly why I wanted to put the filler up as high as possible. I think it would be ideal to have it even up as high as the little hole that has the Z emblem in it. But of course, that would mean routing tubing all thru the cabin to clear the well house.

[CruxGNZ]

So, what was different on the Camaro that kept the gas from backing up? It didn't have a vent from the factory. It has a vent on the tank itself, but that vent only allows air to flow into the tank... wait, or is it out of the tank? Crap.

[Dan Juday]

The Camaro didn't have a filler tube vent? Hmm, that seems odd. Late model cars don't want to vent vapors to atmosphere for emission concerns. I'll have to pull out my f-body book and do some studying.

[Bartman]

I'm not having any problems with the pump auto-triggering or overflowing and I run the pump at full speed. It may be because my filler neck goes through the body just forward of the opening for the original Datsun unit. I just screwed in a plate to block off the old opening and removing this allows me access to install and remove the filler neck at it's new location. This allows my filler neck to angle towards the wheel well and didn't require me to increase the existing angle in the neck like Mat73GNZ did.

 

I think that mine is a continuous downward feed and that's what prevents it from backing up while I'm filling up the tank. All I need to do is remove a small section of the filler neck so that I won't have the top of the new filler neck sticking out.

 

Edit: Thinking more about my install, I'm wondering if it might be better to cut the top off of the existing filler neck as opposed to cutting a piece out and welding it back together.

[CruxGNZ]

Thinking more about my install, I'm wondering if it might be better to cut the top off of the existing filler neck as opposed to cutting a piece out and welding it back together.

Don't see why not. But, I just measured and you can take a max. of 1 5/8" off the top before you hit the plastic.