Datsun Roadster Forum-311s.org

One solution would be to buy a filler neck from a salvage that fits the cap of your choice. As long as you could find one that’s straight for 2 or 3 inches long and has a vent tube (or you could add a vent tube) you can make up the difference with a longer rubber fill tube.

Seems like a while back somebody on the Roadster Facebook page posted a motorcycle non-locking cap that fit and looked like the 70 cap.

This is funny - I was just explaining to my girlfriend yesterday what a "lid" used to be in drug slang. She had never heard the term and attributed it to being from New York. I said that she just wasn't cool enough. That did not go over well...

I just a bought a spare, NEW, non-locking gas cap from Ebay for my '67 1600. I got it for $22.50. The Suzuki Gas Cap - 44200-23810, as described in the Tech WIKI Parts Interchange section, fits very well, and looks great. I'll save my like NOS locking cap for when I feel !

Giving the Suzuki cap a try. Saw a few listings on eBay, but not one for $22.50. Also a few had some measurements of the inner diameter that suggest this will fit. Will report back after I get it.

Mike M - I had the same thought about a different filler neck...one that would support a wider choice of chrome caps.

I need to do something - the gasket on the current locking cap is falling apart.

-jt

Buy a new gasket from Dean. Nowadays walking in to the parts store to have them match something is pointless. They can't function without out a year and model.

Yes I'm old and I miss those kinds of stores where they hung hoses from the ceiling.The last good one we had here had to close due to structural damage to the building from an earthquake. Thanks a lot city of Seattle where all the merchants want to move out due to crime.

Bwk2000 wrote: Tue Aug 30, 2022 3:28 pm

70-1600 wrote: Tue Aug 30, 2022 3:26 pm Neither of the caps I ordered worked. The tab length on them was too long, and the inside diameter of the caps were too large. Here's the measurements of the filler neck on my car:

IMG_0101.jpeg

IMG_0100.jpeg

I figure a diameter of 1.250 - 1.312" for the cap, and a tab length of 1.500 - 1.625" of the bayonet on the cap.

I've been digging around on the web for something around this size. So far coming up empty (no pun intended).

-jt

What is the width of the two grooves in the tube?
1/2” or 11/16”

Width of the slots (grooves) in the filler neck (tube): .69"

Ok, that’s 11/16”. Also means your car was one of those originally equipped with an evap. system requiring the non-vented filler cap, hence the larger grooves.

Bwk2000 wrote: Wed Aug 31, 2022 2:54 pm Ok, that’s 11/16”. Also means your car was one of those originally equipped with an evap. system requiring the non-vented filler cap, hence the larger grooves.

Correct. The evap system is in the trunk mounted against the back. Here's a pic of the system in the trunk, and my filler neck.

Ahhh … I didn’t realize you still had it hooked up
On the plus side, that likely makes it an original California car - It’s come home

Bwk2000 wrote: Wed Aug 31, 2022 3:58 pm Ahhh … I didn’t realize you still had it hooked up
On the plus side, that likely makes it an original California car - It’s come home

Yep - purchased from the original California owner 30+ years ago, so it never left home. She got it as a present to go away to school in So Cal. She lived in Nor Cal when I bought it off her.

No need to measure, FYI. Just look at how the vent pipe exits the filler neck - if it goes straight out at a 90 degree, it is a 70 evaporative emissions neck. If it points downward along the side of the neck it is the conventional neck.

The Suzuki cap, while fitting the opening diameter of the neck and the width of the tabs, didn't "tighten up". The "depth" of the tabs was too large, and the cap simply spins. Tried "adjusting" the tabs and promptly snapped one off. I'm now going down the path of sourcing a universal 2" diameter filler neck that takes a modern screw on cap. The vendor (Filler Neck Supply Co) advertises a 2" diameter x 6" long neck, and a chrome finished screw on cap. Currently the filler neck is "out of stock". Messaged them on wanting to source these items ASAP. Here are the links, in case anyone is interested:

https://www.fillernecksupply.com/2-univ ... as-engine/

https://www.fillernecksupply.com/harley ... akyn-8669/

-jt

jt,
The Suzuki cap fits perfectly if you change out the filler neck with one from any earlier roadster (they show up on eBay frequently).
Jon

jhayden wrote: Tue Sep 06, 2022 7:26 pm jt,
The Suzuki cap fits perfectly if you change out the filler neck with one from any earlier roadster (they show up on eBay frequently).
Jon

Thanks Jon. The 70 filler neck seems to have its challenges, doesn't it? I'll poke around on eBay before I commit to the path on the Filler Neck Supply site.