Interesting idea and I’m sure it could be made to work.   Another option would be to install the Splash-out valve that one of the members on vmf sells.  You can buy a neck with it installed or buy the valve and install it yourself.

Our hoses are 2-1/4" ID, or at least my 69 is, so that wouldn't work. I came up with one and shared it on 69Stang. It works well and prevents the old girl from getting her tail wet, which can happen when filling or just fast acceleration. Its ridiculous how much can slosh out the back. My design inspired Doug (mentioned by RPM above) who improved and simplified it.
I used to live in California that has the "special" fill nozzles on their pumps, and its practically the only way I could keep dry when filling. The paint finish on the back of the car below the cap is completely flat with no trace of a shine from the repeated gasoline bath. 

Nos681 wrote:

Mach1…what company makes the insert you had used?

NJ507090G2 Fuel Filler Neck Cap Insert from fillernecksupply.com

BobE wrote:

Mach1Driver wrote:

Nos681 wrote:

Mach1…what company makes the insert you had used?

NJ507090G2 Fuel Filler Neck Cap Insert from fillernecksupply.com

Thank you for the info.  However, I couldn't find this part number on the fillernecksupply.com website, could your check the number? 
 

You appear to be correct, they don't list it anymore. Following is the post I made on a couple of forums. Since the hose has a 2-1/4" ID, I would think you could use NJ-1087-F-01 instead. Notice this is specifically for a 69, so you will need to investigate the proper filler neck and hose sizes to use:
Filler Neck Modification 
We all know the problems with filling our Mustangs and fuel vomiting out the back. This is a modification any of us can do if we have a hack saw.
This is what you need:
1. Fuel Neck Filler Pipe 69 - available from cjponyparts.com for $29.99 or from many other sources.
2. Fuel Tank Filler Hose 4” 65-70 from cjponyparts.com for $10.99
3. Fuel Filler pipe Hose Clamp pair 65-70 from cjponyparts.com for $12.99
4. NJ507090G2 Fuel Filler Neck Cap Insert from fillernecksupply.com for $12.95
Cut the filler neck 2” down from the flange on the radius of the arc in the neck. Clean it up with a file and if you don't want it to rust take it to a local plater; Google “metal electroplating your zip code”, or use a fuel tank sealing product to coat the edge of the flanges where cut.
I have the flapper pop-rivited to the lower section of the filler pipe. Sorry, this forum limits upload size and I'm not going to hyperlink pictures from off site.

 

Last edited by Mach1Driver (6/16/2024 7:17 AM)

I found the part referenced by Mach1Driver.




As I was trying to find it, I ran across a filler tube that might be worth looking at as well.

The 93-97 Ranger has a double hose setup that might work better.
The internal hose is the fill hose and external is the vent back to the check flapper.
A new filler neck is available at Rock Auto and Filler Neck supply has a plastic fuel inner hose for this purpose that can be cut to length as required…inner fill has to be longer than the external vent.

Filler Neck Supply has same Ranger filler neck at 3x’s the price.
Probably made by same supplier of parts…just my guess.


Rock Auto has them as assemblies with internal hose too.

Last edited by Nos681 (6/16/2024 10:14 PM)

BobE wrote:

Nos681 - thank you for this info, I'll check it out.  
I'm guessing lebow-eaton bought the rights to NJ507090G2?  (although it seems strange to me) 

I finally found the document I made years ago and converted it from Word to a PDF, then parked it on my Google Drive folder. Most forums don't allow uploading of large files, so I parked several useful documents on Google Drive. Using the link above, you have free access to all the documents in this directory. :
https://drive.google.com/drive/folders/10FqYlsGT1XXr8B5TCF9WAASkU4vdPtuJ?usp=sharing
This one is titled "Mustang filler neck7.pdf".




 

Thanks Mach1Driver!

Very nice document.

Waaalllll.... yeah. There's a $5 word for it called punctilious. 

Sounds like someone is being called a sissy punk.
...I read the definition; but, that is what is sounds like.  Almost fighting words.
 

Mach1Driver wrote:

Yeah it might after a few beers:
https://www.youtube.com/watch?v=fjK2xlGaPjs

As a fellow engineer, I appreciate the attention the detail.