LTX and LSX Putting LT1s, LS1s, and their variants into Third Gens is becoming more popular. This board is for those who are doing and have done the swaps so they can discuss all of their technical aspects including repairs, swap info, and performance upgrades.

4th gen gas tank into a 3rd gen???

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Old Sep 6, 2005 | 07:30 PM
  #1  
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From: Amarillo, TX
Car: 1991 Z28
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4th gen gas tank into a 3rd gen???

i'm swapping my car over to an ls1 and an auto, just curious if the gas tanks are the same between the two generations. i'd like to use the 4th gen tank if it bolts up.
Thanks,
Adam
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Old Sep 10, 2005 | 04:18 AM
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It'll bolt up, but you'll have to shorten the filler neck and completely do your fuel lines and wiring. I had to do mine to comply with CA requirements.

Adam
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Old Sep 10, 2005 | 09:24 AM
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awesome! Thanks!
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Old Sep 10, 2005 | 11:40 AM
  #4  
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From: Lyndonville, VT
Car: 89 Firebird Formula
Engine: Custom Forged 402ci LS2 w/STS Turbo
Transmission: T56 6-speed
Axle/Gears: Moser 9" with 4.11
You're welcome.

I thought it was kinda cool (but weird) to see another 3rd gen owner with SOM paint AND my name.

I've got a 91 Camaro RS I'm doing next, putting in a 2001 LS1 with low miles, haven't decided on transmission yet, or the color. Definitely gonna do something different with it though, and maybe scissor doors as well.

Your car looks SWEET, dude. I hope my Camaro comes out as nice as yours did. I would definitely say that your Camaro and my Formula are two of the nicest third gens I've seen out there.
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Old Sep 10, 2005 | 01:40 PM
  #5  
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damn, i didnt even notice! Thats a really clean Formula!!! What hedders did you go with? Thanks for the compliments, i just cant wait to get it done! lol
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Old Sep 10, 2005 | 04:20 PM
  #6  
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From: Lyndonville, VT
Car: 89 Firebird Formula
Engine: Custom Forged 402ci LS2 w/STS Turbo
Transmission: T56 6-speed
Axle/Gears: Moser 9" with 4.11
I'm using the LT headers from Hawks. (Same site as my pictures are on, and a sponsor here).

Yeah, it's hard waiting........... it's been a year and half on my car so far. But, I keep telling myself that once it's done, it'll be worth the wait.
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Old Sep 15, 2005 | 06:16 PM
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Car: 1988 GTA TRANS AM, 1986 TRANS AM
Engine: L98, 5.7 TPI reborn, comp cam/heads maybe HSR this spring 5.0 TPI
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what are the benefits of switching to a 4th gen tank? Is your original one in need of replacement and you just want to get a 4th gen?
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Old Sep 15, 2005 | 11:58 PM
  #8  
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From: Amarillo, TX
Car: 1991 Z28
Engine: 383
Transmission: TH350
I am swapping over everything else from the 4th gen, and thought i might as well do the gas tank too. As far as i know, nothing is wrong with my stock tank, other than its older...
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Old Sep 16, 2005 | 01:09 AM
  #9  
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Car: 13 Ram 1500/ 78 Formy
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are all 4th gen tanks plastic? there's the potential for lighter weight
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Old Sep 16, 2005 | 08:34 AM
  #10  
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From: Maine
Car: 1988 GTA TRANS AM, 1986 TRANS AM
Engine: L98, 5.7 TPI reborn, comp cam/heads maybe HSR this spring 5.0 TPI
Transmission: 700R4
weight reduction, good call. I might try that to lighten up the GTA.
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Old Sep 16, 2005 | 01:26 PM
  #11  
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From: Lyndonville, VT
Car: 89 Firebird Formula
Engine: Custom Forged 402ci LS2 w/STS Turbo
Transmission: T56 6-speed
Axle/Gears: Moser 9" with 4.11
weight reduction
plastic never rusts
if you are in CA, you HAVE to have the 4th gen tank and sensors to pass emissions
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Old Sep 16, 2005 | 10:50 PM
  #12  
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From: Amarillo, TX
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well, the tank i pulled out of the 98 is not plastic, but i'll use it anyway...
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Old Sep 26, 2005 | 09:52 PM
  #13  
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In 99 or 2000 they switched from a metal 15.5 gallon tank to a plastic 16.8.
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Old Dec 8, 2008 | 07:44 PM
  #14  
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Car: 86 Z28
Engine: Stock 305
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Re: 4th gen gas tank into a 3rd gen???

Would an 02 tank from a V6 fit? Is there a difference between the LS1 and V6 tanks? My Z is a carb, I was hoping to just drop the guts into the new tank. It's never that easy though. Any info would be great! thanks
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Old Dec 9, 2008 | 01:35 PM
  #15  
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There are differences between V6 and LS1 with regard to pressure regulation, but the guts from a 3rd gen tank won't fit in the 4th gen tank. Some of the small pieces might, like pick-up strainer, but everything else, from what I could tell, is different.
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Old Sep 22, 2010 | 11:04 AM
  #16  
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Car: 1986 Z28
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by five7kid
... but the guts from a 3rd gen tank won't fit in the 4th gen tank.
When you say 4th gen tank, are you talking about just the plastic ones? From what I've gathered searching, I thought the older LT1 tanks were a direct replacement fit.

Got a buddy who needs a new gas tank, rules say it must be the same as original. Hoping if the LT1 is identical, it will make the junkyard hunting easier.
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Old Oct 10, 2011 | 01:15 PM
  #17  
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Re: 4th gen gas tank into a 3rd gen???

I heard there are baffles in a 4gen tank? I got tired of it cutting out in my old car on a hard turn
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Old Oct 10, 2011 | 11:00 PM
  #18  
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From: MD
Car: 88 Iroc-z
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Re: 4th gen gas tank into a 3rd gen???

I also have a fourth gen tank in my car. They switched to plastic in 99 as my tank is from a 99. I did my swap like you, reused alot from the fourth get, hell I even used the washer bottle! Lol
Attached Thumbnails 4th gen gas tank into a 3rd gen???-2011-07-24_20-27  
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Old Oct 11, 2011 | 05:51 AM
  #19  
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by 91camarosRS
I heard there are baffles in a 4gen tank? I got tired of it cutting out in my old car on a hard turn
I don't know about the early 4th gen metal tanks but the LS1 car's plastic tanks pretty much eliminated the starvation problem. The OEM pump is mounted inside a plastic bucket type arrangement where the the plumbing is setup to scavenge the fuel from the lowest part of the tank and keep the bucket filled. I have run mine down to where I put almost 15 gallons in at a fill-up without starving in corners.

M
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Old Aug 15, 2022 | 04:00 AM
  #20  
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Re: 4th gen gas tank into a 3rd gen???

[QUOTE=89FormulaLS2;2524570]It'll bolt up, but you'll have to shorten the filler neck and completely do your fuel lines and wiring. I had to do mine to comply with CA requirements


hey broths nice to hear someone is dealt with the California emissions you mind reaching out want to do the same and have some questions thank you!!
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Old Jan 18, 2023 | 03:27 PM
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Car: 1991 Firebird Formula
Engine: L98
Transmission: 700R4
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Re: 4th gen gas tank into a 3rd gen???

What are you guys using for the filler neck tubing? I am about to put mine in when I swap this 10 bolt rear end for my new Strange Dana 60 rear end.
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Old Jan 19, 2023 | 03:19 PM
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Re: 4th gen gas tank into a 3rd gen???

LS1 4th gen tank has a rubbery filler tube. Pull the filler tube off the tank, cut off about 2 to 2.5 inches length, and clamp the hose back in place.

It's an oetiker clamp if I remember right, so you'll need the special tool to tighten that up again. Or replace with a damn good clamp, no worm gear on that one.

Last edited by QwkTrip; Jan 19, 2023 at 03:26 PM.
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Old Jan 19, 2023 | 03:31 PM
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From: McKinney, TX
Car: 1991 Firebird Formula
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Axle/Gears: 3.23
Re: 4th gen gas tank into a 3rd gen???

Originally Posted by QwkTrip
LS1 4th gen tank has a rubbery filler tube. Pull the filler tube off the tank, cut off about 2 to 2.5 inches length, and clamp the hose back in place.

It's an oetiker clamp if I remember right, so you'll need the special tool to tighten that up again. Or replace with a damn good clamp, no worm gear on that one.
Yeah mine didn't come with the rubber section so I'm wondering if anyone else had to source the rubber section separate from the tank and where they got it from.
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Old Jan 21, 2023 | 10:44 AM
  #24  
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From: McKinney, TX
Car: 1991 Firebird Formula
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Transmission: 700R4
Axle/Gears: 3.23
Re: 4th gen gas tank into a 3rd gen???

If anyone has a picture of the rubber section I have found some fuel compatible 1 3/4" ID hose with various angles preformed. Also Dayco has some flex hose that is fuel compatible. If anyone has some dimensions to give me and let me know if both sides are 1 3/4" ID that would be helpful.
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Old Jan 22, 2023 | 07:06 AM
  #25  
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Re: 4th gen gas tank into a 3rd gen???

When I swapped the plastic tank into my Camaro a decade or so ago I found that filler hose to be my biggest issue. It is a preformed hose with different size ID ends. Using the 4th-gen filler neck requires cutting off a length of one end. I don't remember what the ID sizes are or how much the trim is to fit it. Retailer searching ever couple of years for a new replacement has yielded zero direct replacements. I remember seeing a bit of a thread or two here and other forums where one could be cobbled together from straight fuel hose and adapters. That's all the info I can provide.

M
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Old Mar 8, 2023 | 07:55 AM
  #26  
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From: McKinney, TX
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by mwfrels
When I swapped the plastic tank into my Camaro a decade or so ago I found that filler hose to be my biggest issue. It is a preformed hose with different size ID ends. Using the 4th-gen filler neck requires cutting off a length of one end. I don't remember what the ID sizes are or how much the trim is to fit it. Retailer searching ever couple of years for a new replacement has yielded zero direct replacements. I remember seeing a bit of a thread or two here and other forums where one could be cobbled together from straight fuel hose and adapters. That's all the info I can provide.

M
Well I found a solution that requires no modification.
Purchase the metal fuel filler neck and fuel cap from O'Reilly's
Precision Fuel Tanks Fuel Filler Neck - FF1022
Stant OE Equivalent Emission Control Fuel Cap - 10836

Then go to FillerNecksupply.com and purchase this filler tube:
Rubber Fuel Tank Filler Hose D125L10B01
This tube has a smaller end on one end to fit the filler neck and large one to go on the tank.

Perfect fit. Hope this helps anyone else that runs into this issue. Took me weeks to find the right parts.
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Old Mar 8, 2023 | 05:50 PM
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by Blown_WS6
Well I found a solution that requires no modification.
Purchase the metal fuel filler neck and fuel cap from O'Reilly's
Precision Fuel Tanks Fuel Filler Neck - FF1022
Stant OE Equivalent Emission Control Fuel Cap - 10836

Then go to FillerNecksupply.com and purchase this filler tube:
Rubber Fuel Tank Filler Hose D125L10B01
This tube has a smaller end on one end to fit the filler neck and large one to go on the tank.

Perfect fit. Hope this helps anyone else that runs into this issue. Took me weeks to find the right parts.
That's getting bookmarked. Thanks for sharing.
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Old Mar 8, 2023 | 07:12 PM
  #28  
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Re: 4th gen gas tank into a 3rd gen???

I had been searching off and on for a couple years for a replacement filler neck hose for a plastic tank I have. I ordered from that same site a couple days ago. Hopefully others find this thread before wasting hours searching.
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Old Mar 9, 2023 | 03:05 PM
  #29  
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Re: 4th gen gas tank into a 3rd gen???

I forgot to attach the picture of the semi final product. The fuel tank isn't in the car yet but the angle and length matches the old 3rdgen tank filler neck perfectly.
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Old Mar 11, 2023 | 04:47 PM
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Re: 4th gen gas tank into a 3rd gen???

Mine showed up yesterday, fit's great and looks like a nice piece. Looks better in person than in the pictures. Didn't see a need to take pictures since once has already been posted, but another thumbs up for the FillerNecksupply.com filler hose.
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Old Mar 11, 2023 | 05:09 PM
  #31  
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Re: 4th gen gas tank into a 3rd gen???

Wow!

Excellent find!!!
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Old Jul 10, 2024 | 08:44 PM
  #32  
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by Blown_WS6
I forgot to attach the picture of the semi final product. The fuel tank isn't in the car yet but the angle and length matches the old 3rdgen tank filler neck perfectly.
do you by any chance might know the part number ? Thanks! in advance.
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Old Jul 14, 2024 | 02:53 PM
  #33  
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Re: 4th gen gas tank into a 3rd gen???

Originally Posted by 89Iroc-z!
do you by any chance might know the part number ? Thanks! in advance.
You bumped an old thread where the part numbers are already listed?
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