The Stovebolt Site Forums The Shop Area Engine Shop Fuel filler neck angle

Feel free to move this thread. It’s fuel system related so I will put it here.

One of the first things I did when I acquired my 51 3100 some 8 years ago was redo the entire fuel system. That included a new Spectra, made in Canada, fuel tank. I noticed back then that I couldn’t get the filler neck to the same angle as before. It was too horizontal. I fiddled with it quite a bit, finally gave up and moved on with my life.

Fast forward to present day when the truck gets driven fairly frequently. The horizontal-ish fuel neck makes it almost impossible to fill the tank without overfilling and spilling down the side. More than just a mild annoyance now.

I have a few ideas how I might correct this condition: Some shortening of the tubes for tank and/or neck, with a more flexible hose in between. Some gentle bending of the tubes ay the tank. Etc.

Before I go reinventing the wheel, wanted to see if others have encountered this problem and how they went about fixing it.

Is the Spectra tank an exact copy of a stock 3100 tank? If not, why did you go that route?

It was supposed to be an exact copy.

Yes. See the other thread about gas tanks and Skooter's picture. Mine photo is distorted.

I'm not sure what you mean JW51. The filler neck is anything but horizontal.

I've never had a problem filling the tank. Don't use the latches on the pump or it will fill up too fast and spurt out.

Hold the trigger by hand and don't shove it in all the way. Air needs to escape.

This procedure is true for all my old cars that will puke if you rely on the automatic shutoff.

I’m not suggesting that the neck coming out of the tank itself is horizontal, but there is something about it that makes the “other” neck too horizontal as it exits the truck. Not truly horizontal, but much more than it should be.

I will try to get a pic that illustrates what I’m talking about.

Mine is a 52 but I've owned a 1951 in the past and as I recall it was the same. I have one of the Spectra tanks and it fit perfectly. The only thing I recall about the filler neck is that when I replaced the rubber grommet I had to be careful to orient that grommet so that the angle was just right...that being the filler neck had to point right at the two filler tubes on the tank when I was finished or it clearly wasn't going to fit right. I do recall having to move it around a time or two but hopefully you can see in the two images attached it fit fine once I got that done.

Do you have a pic of how the filler neck looks on the outside of the truck?

I didn't, but I do now. It looks like this...

Yep, that is more vertical than my filler neck. I will capture a picture of mine this evening.

Did you also replace the filler neck itself when you did your fuel system work? From the pic it looks like the neck has more of a bend than the other pic? Just my 2cents

No, the images I posted are of the same neck and as far as I know it was the one that originally came on the truck. The only change was a locking gas cap. As I said the replacement grommet made me work to get it pointed in the direction I wanted and I did learn being off even a small bit can make your filler neck point differently from where you want it. It also wasn't as easy to mate the neck with the new rubber connecting hoses as I hoped it might be, but once I got them in there I found I could move them. Since there are two, you have to be patient when aligning them, but no more than you'd expect I guess.

Pic of my filler neck.

I think you just need to remove the filler neck and rotate the grommet until you get the right degree of slope to match your tank tubes. If you need a new grommet, now might be a good time to get one.

I’ll give it another shot. I’ve messed with so many different ways thinking I’m just missing something easy. Don’t really think it’s that simple, but worth one more look.

I'm certain the gas tanks for at least the 1950 through 1952 3100s were the same and I know the cabs were the same so logic and a search using the big search engine tells me the filler necks were the same. When you try again look please at the grommet. Mine (can't remember where I got it) had an angle built into it and that angle was the important factor. Good luck!

I’m sure you’re right about the tanks being the same. My theory has always been that I just got a slightly defective tank.

My grommet was also angled to hold the filler neck. I bought it from NPD. Long side pointed down.


I tried to find as many pics of the filler neck on the fuel tank as I could. You can see the old tank and new tank are virtually identical. I re-used the original fuel filler neck that connects to the tank with a rubber fuel hose.

Maybe your fuel hose section is too long, making the fuel inlet stick straight out instead of angled? The rubber hose should be a short , straight section with no bends.

Thanks, Otto. That third pic, in particular, will be a really good reference point.

My filler neck. JW51, your filler neck looks almost horizontal to the vertical cab metal. Can't tell if your neck grommet is rotated wrong or what? Also it would be nice to see a interior pic of filler neck connecting to the to the tank. If the tank is the same size as what we would expect, I wonder about the angle and length of the tank's neck which the filler neck connects to.

I wonder if JW's filler neck is from a different truck?

That has long been my theory. The tank neck is too long and/or at a slightly wrong angle.

I’ll get an interior pic posted here this evening.

New ones are available cheap from everywhere.

Y’all’s (All Y’all’s?) pictures have helped me figure it out. To achieve an angle similar, the filler neck needs to rotate clockwise if you were standing outside the truck facing the door. And if the neck is rotated in such a fashion, the connective hoses are too short and perhaps a bit too stiff. Some new hoses and a new grommet, and I will be able to make it work.

I couldn’t prove it without another truck to compare side by side. But I think the root cause is actually a tank inlet that is oriented too vertically and makes the alignment to the cab opening/grommet᠁..all wonky. Looks to me like Otto’s and Jon’s tanks have inlets that are a bit shallower. My crummy pictures might help illustrate. Best I could do without removing the seat back.

Incidentally, I ordered the hoses from Jim Carter at the time I bought the tank (which I believe came from Rock Auto).

It may be an optical illusion but it appears that if your filler tube and vent hose were inserted further into the connector hoses that it would be angled down more and protrude from the side of the cab less with a more desireable angle.

I’ll have to take another look at that possibility. I do see what you mean just looking at the photos.

However, the way things are aligned currently sort of represents “the best” fit I could achieve with the combination of parts. If you move the neck closer to the tank, the the mismatch of tank inlets and the filler neck becomes harder to solve with the hose. At least that’s the way I recall it without the truck in front of me.

Your pictures look like the filler neck coming out of the fuel tank is at the wrong angle. It appears to be straight up rather than at 45° angle pointing toward the fuel tube. Was that a new tank? If so how did it look compared to the original tank?

Agree with Otto. The lower filler neck (attached to the tank), looks too vertical. Compared to Otto's pics, the mounting surface of the tank where the lower filler neck attaches looks like it is angled more towards the front as Otto's looks like it is leaning more towards the side Wish we had a frontal view of it. Is the seat back removed?

I also notice that the upper vent tube looks much further away from the upper filler neck, as compared to the lower vent tube's position to the lower filler neck. Thus the connection of both vent tubes looks like it needs some attention. Might tweak the welded bracket that holds the upper vent tube, to bring the tube closer to the filler neck.

It was a brand new Spectra Tank. It's been a long time. I think this was a matter of "not knowing how little I knew" and the original tank was pitched before I had a chance to do a direct comparison. This was a younger, and much dumber, version of me as it relates to aftermarket parts. The Spectra tank was pretty universally praised as a perfect replacement, and I think that's still the case. For what it's worth, I think all the praise is probably deserved. Maybe I got a one-off defect? Or could it be that Rock Auto shipped the wrong thing....a tank for a different application?

Anywoo, I agree with your assessment...sure looks like the tank itself is to blame. I'm sure I can modify something and make it all work much better than it does currently.

When I tear into this problem, I will remove the seat back and get a better pic. Last night we were packing for a family vacation that begins today. Horsing around in the garage with my old truck was not a very popular allocation of my time.

I did what I could given the circumstance.

What? You're not staying home to work on the truck while the family takes off for vacation? LOL
Have a good time.

Get your priorities straight, Man!

True story: Played a little prank today. I put a carburetor on the middle console just as we were about to leave in the family chariot. Told my wife I was gonna rebuild it on vacation for something to pass the time.

Her reaction was priceless and exactly what I predicted.

And now your looking for a doctor to remove it from your ear.

Good one!

More likely he'll need a proctologist.

Ha. This was the phase of “trying to leave” where everyone is going back in the house to get things we almost forgot. I waited for my wife to step away and whispered in my daughter’s ear᠁.”Watch this.” Went in the garage and got the carb and brought it back to the van.

She stepped right in my trap. Mid-freak-out we informed her it was a joke.

I didn’t have a rebuild kit, anyway. Otherwise I might have been half serious.

I took oil, filter, and tune up stuff for maintenance on the Cadillac on trip to Florida. My girlfriend thought it was a smart idea.

Back to the subject ........the more I study both JW51's pics as well as Otto's, to me one could consider tweaking the lower filler neck angle by shoving a large diameter wooden rod into the lower filler neck and persuade the neck more towards the side. This though, would mean removing the tank for there would be no room for a large wooden rod to be inserted while the tank was in truck. Maybe someone has another idea. Think I'll look at my lower filler neck angle tomorrow.

Yes, I'd pull the tank out and do as you suggest with a large diameter dowel like those used on patio umbrellas. An appropriately sized piece of PVC pipe would probably work, too.