Jump to content
HybridZ

280z gas tank swap into early 240z


zgeezer

Recommended Posts

The swap is easy, but not a complete simple R&R.

 

The 280 tank out of any 280 without the false floor and shallow spare tire well will work.

 

The 280 tank is longer, it is deeper, and it lacks one of the tank vents on 240's. The 280 tank's fuel level sensor is interchangeable with the sensor and float of the 240. The 280 has an additional sensor, which I think is a pressure sensor attached to the fuel level float arm.

 

The 240 fuel tank straps are both too short to mount the 280 tank. You will need 280 straps. I think 280 straps mount in the body in the same fashion as the 240s, but I'm not certain.

 

The passenger's side fuel tank strap indentation on the 280 is located the same as the 240. However, the 280 strap indentation on the driver's side is located about 2 inches wider to the driver's side than the 240. A longer strap from the 240 mounts would secure the 280 tank, but will not fit into the 280's indentation.

 

The 280 tank is well baffled. The 280 tank fuel feed and return are both larger than the 240 tank. The 280 return line is the same size as the 240 main feed. The 280 fuel feed line is substantially larger.

 

I have a number of photos posted on my album under zgeezer that illustrate the differences. I'll try to mount them here.

 

280ZGas_Tank_240z_Gas_Tank2.JPG

 

This shows the length, the lack of a vent, and the relocation of another vent.

 

280Z_Gas_Tank_Depth1.JPG

 

It's a little dark, but the depth of the 280 tank is a little less than depth of that block of wood. I think 2 inches.

 

280z_Gas_Tank_Baffle1.JPG

280zGastankComparison12.JPG

 

I think the 280 tank is well baffled.

 

Here is the reason I'm attempting this installation.

 

280Z_Supply_and_return_lines.JPG

 

280Z_Gas_Tank_Supply_Return.JPG

280Z_Gas_Tank_Supply_Return.JPG

 

280z_240z_fuel_level_sender.JPG

 

The fuel level senders are interchangeable between 280 and 240. The 280 has an additional sensor, which I believe to be a pressure sensor. I don't know if the ohm readings of the two sensors are the same.

 

280Z_Gas_Tank_Vents.JPG

 

240Z_Undercar_depression_wheel_well.JPG

 

This depression in the bottom of the 240 spare tire well is shot from underneath and it matches a similar raised ring on the 280 gas tank.

 

 

g

Link to comment
Share on other sites

Also, Tony D indicated that you do not need to source different straps, simply use a longer J-bolt. I have not confirmed this myself. I just had my 240z tank modified by a local speed shop that specializes in custom fabrication.

Link to comment
Share on other sites

  • 4 months later...

nice post. has anyone put a 240 tank onto a 280? i have a 280 and theres a HUGE dent right in the middle of the tank, its ugly. also i think the 240 tanks look sleaker with their sloped bottom. would the 240 tanks be just as easy to fit onto the 280?

Link to comment
Share on other sites

Wow, seeing the two of them side by side really indicates some visible differences. Guess that 'shortness' has to do with the bumper shocks and extra shielding they put around the mufflers on the EFI cars... Anybody got some side by side shots of the 260 tank next to the 280? I have also swapped 260 tanks into 240's using the longer bolts...and from what I recalled the external dimensions were similar to the 240/280 tank comparo as shown above. On the 260 to 280 swap as I recall, all I did was back the nuts on the 'j' bolts out further to make the tank slip in, so the 260/280 tank may be external dimensional clones, the only difference being the pickups and possibly the baffling internally...

 

BTW, the second sensor on the 280 tank sender unit is a capacitance unit that lights the red 'low fuel' light in the gas gauge on the later cars. A nice feature if you're like me, and know "I can go 72 miles from the time the light turns on in the Truck"... Makes a difference when Eherenberg is only 68 miles away, and that simply crossing the border from Blythe to Exit 1 on the Arizona Side means gas for 30 cents a gallon cheaper! LOL

 

Great Photos, BTW. That makes explanations much easier!

Link to comment
Share on other sites

Wow, seeing the two of them side by side really indicates some visible differences. Guess that 'shortness' has to do with the bumper shocks and extra shielding they put around the mufflers on the EFI cars... Anybody got some side by side shots of the 260 tank next to the 280? I have also swapped 260 tanks into 240's using the longer bolts...and from what I recalled the external dimensions were similar to the 240/280 tank comparo as shown above. On the 260 to 280 swap as I recall, all I did was back the nuts on the 'j' bolts out further to make the tank slip in, so the 260/280 tank may be external dimensional clones, the only difference being the pickups and possibly the baffling internally...

 

My late 260Z is carb'd and has a tank that looks identical to the 280 tank shown above. The fittings are in the same locations, but I cant verify the baffling or internal pickups as I havent dropped it from the car (yet).

 

 

 

- Greg -

Link to comment
Share on other sites

I hate to burst your bubble, but I don't think this swap is worth it if you're trying to combat fuel starvation in corners. I went through the trouble of putting a 280 tank in my 240, and with a high flow Walbro fuel pump, it was sucking air in hard left turns at not much below a half a tank. I ripped the 280Z tank out and put my 240 tank back in with a sump welded to the bottom. The best solution would be to run a surge tank which has been discussed extensively elsewhere on this forum.

 

Believe me, I was extreemly frustrated after spending a lot of time and money to get the 280 tank in the car and still have starvation problems.

 

Nigel

'73 240ZT

Link to comment
Share on other sites

I hate to burst your bubble, but I don't think this swap is worth it if you're trying to combat fuel starvation in corners. I went through the trouble of putting a 280 tank in my 240, and with a high flow Walbro fuel pump, it was sucking air in hard left turns at not much below a half a tank. I ripped the 280Z tank out and put my 240 tank back in with a sump welded to the bottom. The best solution would be to run a surge tank which has been discussed extensively elsewhere on this forum.

 

Believe me, I was extreemly frustrated after spending a lot of time and money to get the 280 tank in the car and still have starvation problems.

 

Nigel

'73 240ZT

 

 

EXCELLENT POINT NIGEL!

This is EXACTLY the phenomenon I was talking about in the 'build a nice surge tank' post! Just because you have a 280 Tank does not mean you can't run dry or that you don't require an external surge tank!

 

I have said it before, even on triple Mikuini Cars, the Datsun Competition Manual used two fuel pumps and a surge tank to fuel N/A 240's in competition!

 

The surge tank is more of an issue to solve cornering problems with fuel starvation, and it's combatted by making a vessel taller than it is wide so that during cornering the outlet (pump suction) is always flooded.

 

The nice thing about the 280 Tank is that for a normally driven street car, it will perform satisfactorily for most of the people out there in daily driven activities. If you are racing, a Surge Tank is ALWAYS a good idea, EFI OR N/A!

Link to comment
Share on other sites

  • 2 years later...

So I'm installing the 280 tank in my 240Z. I have the passenger side strapped up, but I'm about an inch short on the drivers side. I tried both 240 and 280 straps and J bolts. Where can i find longer J bolts?

Also, my filler neck barely touches my gas tank inlet. There is no way that I can clap it down. Are the 280Z filler necks longer? Thanks

Link to comment
Share on other sites

So I'm installing the 280 tank in my 240Z. I have the passenger side strapped up, but I'm about an inch short on the drivers side. I tried both 240 and 280 straps and J bolts. Where can i find longer J bolts?

Also, my filler neck barely touches my gas tank inlet. There is no way that I can clap it down. Are the 280Z filler necks longer? Thanks

 

I dont know about the filler strap but you can get a j bolt off a hardware store most likely or cut a batterey j bolt laying around if you got an extra.

 

Nigel and TonyD thanks for that

I recently got the l28et finally running in the 240z and I was contemplating the 280z tank or surge tank idea. Since my 240 tank is leaking at the sender (prolbally O ring) and is also leaking from pick up, return or vent (it looks like its crappily brazed on there)

 

I know what I am going to do now. Dont want to hijack but I would like to ask a couple questions if I keep the 240z tank Is it a good idea to remove reserve tank and plug the vents?Theres too many! How about the reserve tank I saw a post here someone using the reserve tank as a surge tank.

Link to comment
Share on other sites

It's not a reserve tank, it's a vapor/liquid separator. You can run without it, but I have it in most cars, I just convert to 3/8" vent lines from 15mm to keep good easily replaceable hoses back there. Some nylon couplers from 15mm to 10mm is all you need, and no more $100+ molded vent hoses needed!

Link to comment
Share on other sites

I hate to burst your bubble, but I don't think this swap is worth it if you're trying to combat fuel starvation in corners. I went through the trouble of putting a 280 tank in my 240, and with a high flow Walbro fuel pump, it was sucking air in hard left turns at not much below a half a tank. I ripped the 280Z tank out and put my 240 tank back in with a sump welded to the bottom. The best solution would be to run a surge tank which has been discussed extensively elsewhere on this forum.

 

Believe me, I was extreemly frustrated after spending a lot of time and money to get the 280 tank in the car and still have starvation problems.

 

Nigel

'73 240ZT

 

I didn't add a sump to my tank, but I did tap the drain plug for 3/8 NPT and added a fitting there to to pull fuel from, and have not experianced any issues with fuel starvation, when the tank is above about a 1/4, and I'm not corning hard. I haven't ran any track days yet, that's not really my thing, but for daily (spirited) driving and drag racing this seems to work well. BTW this is on the original '73 240 tank.

Link to comment
Share on other sites

I didn't add a sump to my tank, but I did tap the drain plug for 3/8 NPT and added a fitting there to to pull fuel from, and have not experianced any issues with fuel starvation, when the tank is above about a 1/4, and I'm not corning hard. I haven't ran any track days yet, that's not really my thing, but for daily (spirited) driving and drag racing this seems to work well. BTW this is on the original '73 240 tank.

 

Thats exactly what I have a 90 degree 3/8 barbed fitting there. Problem with this is your picking up crud at bottom of tank> I dont know how long that walbro is going to last I should put an inline see through filter. Just dont know which to go with yet.

 

Oh I thought it was a reserve tank what an odd thing. I got rid of it . Too many fuel vent hoses going into the car its bad enough with the l28et fumes and 240z holes that will be needing to plug.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...