Aux tank from a Camaro (1 Viewer)

[WCBlueSky]

I've been carrying several gallons of fuel on the roof rack for long trips, but I want to free up room on the roof and eliminate the hassle of siphoning. I would have loved to get an OEM 80 subtank, but they are hard to find in the US and expensive to import from AUS. A Long Range Automotive 24 gallon aux tank is another option, but it is also $$ and hangs down too low for my liking. Other members here have fit aux tanks from an Isuzu Trooper, Chevy tracker, and Chevy S10 Blazer, but these tanks also hang down too low for me.

So I looked at the dimensions of every fuel tank I could find online and chose an 18 gallon GM32A tank from a '68 Chevy Camaro. It fits the available space extremely well without sacrificing clearance. The tank strap indentations line up well enough with the body rails, so I can use mounting points on the body similar to the OEM subtank.

Fitting this tank does have some challenges though. The tank spout needs to be moved to the side, and a vent pipe needs to be added. I considered welding (new tank so no danger of explosion), but the tank is electroplated with nickel, then hot dipped in lead-tin (i.e. Ni-Terne steel), and welding will destroy this coating. So I'm planning to solder instead. I will need to reroute the exhaust since it contacts the back of the tank. The top of the tank also contacts the filler neck tube, so the top corner of the tank will be dented down to give clearance. I got an extra filler neck from the salvage yard and I'm planning to slightly reroute the filler neck tube to minimize the amount of tank "smashing" needed. Planning to build a "Poor Man's" dual filler neck following goranvolvo's ingenious design. I bought Camaro tank straps, but they are only 16 gauge and seem really weak, so I will fab up tank straps out of something thicker.

I will also add a skid plate for extra protection. Since steel prices are sky high right now, I got two ZJ (1993–1998 Jeep Grand Cherokee) gas tank skid plates from the salvage yard that I will fab into one larger skid plate. They are 12 gauge steel and pretty stout--much better than the ~22 gauge steel of the gas tank.

If I have time, I also would love to build a microcontroller circuit that does all the fuel management automatically by reading the fuel level senders in both tanks, driving the aux fuel pump, and PWM'ing the fuel gauge in the cluster with the combined amount. But the first step is just a toggle switch on the aux fuel pump.

 

[WCBlueSky]

Reserved for more pictures.

 

[WCBlueSky]

Reserved for more pictures.

 

[mudgudgeon]

Cool project.

I used a Prado tank as a sub tank to increase capacity over the OEM subtank capacity in my 105 series cruiser.
There's many very generic shaped tanks that could be used in the same way.

welding will destroy this coating. So I'm planning to solder instead

Won't heat from soldering also destroy coatings?

To get a good solder joint you need to form a close fitting sleeve or collar around the pipe so the solder is sealing the joint, not holding it together so much. The better you can shape a collar, the more reliable it will be.

I'd be inclined to weld, then treat affected zone with an epoxy paint.

 

[WCBlueSky]

Won't heat from soldering also destroy coatings?

To get a good solder joint you need to form a close fitting sleeve or collar around the pipe so the solder is sealing the joint, not holding it together so much. The better you can shape a collar, the more reliable it will be.

I'd be inclined to weld, then treat affected zone with an epoxy paint.

The tank is basically coated with solder (terne = lead/tin alloy), so it should be easy to add more solder without hurting the coating. Strength of soldering is a concern though--I was thinking of adding a tight fitting collar around the pipe as you mentioned to get more surface area for the solder to "stick". The problem with welding is that it will destroy the coating on the inside of the tank too, which is harder to treat, but probably not impossible--this is something to consider. I'm planning to weld the filler neck, which will destroy the zinc coating in the HAZ as well. There are fuel tank liners (e.g. Fuel Tank Sealer - https://por15.com/products/fuel-tank-sealer) that I could use, but I'm inclined to just wait until it rusts (if ever). I live in a place with very little rust so I'm probably overthinking it.

 

[gummycarbs]

Can you take some pictures of it in the installed position (on the jack)? I'm curious to see how close to the frame rails and exhaust it is.

I settled on a ~24 gallon Ford F150 rear tank (~1996 model, I believe), but I got bogged down in details and the project stalled. The F150 tank would extend slightly below the frame rails, but I might be able to fix that if I were to hammer a dent in it for better exhaust clearance.

My plan is to use a Pollak 42-302 fuel selector. Since they apparently die often from debris, I plan to eliminate the factory fuel filter and add a filter immediately after each tank, before reaching the fuel selector.

I'll be interested to see what you come up with.

Oh, and I was going to Silicon-Bronze braze any modifications, but that will still probably destroy and coating. But at least the joint itself wouldn't rust. Solder sounds interesting. Maybe I'll mock something up to test its strength.

 

[WCBlueSky]

Can you take some pictures of it in the installed position (on the jack)? I'm curious to see how close to the frame rails and exhaust it is.

Sure. There is about 1.5" space on each side of the frame rails, and about 0.5" space on both front and rear. This includes the tank seam lip, which could be bent in a little for more clearance if necessary. I already cut the exhaust, it was making contact on the back of the tank, so it will be rerouted.

 

[WCBlueSky]

I mocked up the skid plate. Flipped backwards (from the way it was in the Jeep), it matches the contour of the gas tank very nicely. I was originally planning to mount the gas tank to the body, but I'm tempted to mount it to the skid plate instead, which will be mounted to the frame.

 

[gummycarbs]

Sure. There is about 1.5" space on each side of the frame rails, and about 0.5" space on both front and rear.

I'm impressed. That really tucks up there nicely.

 

[WCBlueSky]

That really tucks up there nicely.

Yeah, the GM32A tank I got has dimensions of 39-3/8" x 20-7/8" x 7-3/4". GM32B is the same size as well, but has a longer spout (that would be relocated anyway). If I were to do it over again, I would probably get GM42B with dimensions 40-1/8" x 20-5/8" x 7", which is also 18 gallons, from a '71 Camaro. I was worried about fitting between the frame rails so I got the narrower tank, but there is plenty of room and would gain a little more clearance.

They also make stainless steel versions of these tanks, which would be really nice, but they are about twice as expensive as the Ni-Terne coating. And there is a zinc galvanized version which is a little cheaper.

I looked at a ton of other tanks from all different types of cars, but nothing else matched the dimensions I was looking for.

 

[Outsane]

Cool project!

 

[Arizona Jeff]

Following!

 

[woodsman 44]

I like how the Camaro tank tapers up in the back...better clearance/departure angle.

18 gal. seems to be the perfect size..

 

[woodsman 44]

So they make the stainless in the GM42B?

any Idea on price for the 18 gal stainless?

The stainless would be easy to weld on to....with not ruining the coating of the other styles

 

[WCBlueSky]

So they make the stainless in the GM42B?

any Idea on price for the 18 gal stainless?

The stainless would be easy to weld on to....with not ruining the coating of the other styles

Yeah, stainless steel tanks are around $250 to $300: for example here and here. I saw a GM32B stainless steel tank on the Holley website on clearance for half off (gone now) and seriously considered buying it, but I already purchased the Ni-Terne GM32A. Mig welding stainless would be super easy with the right gas. However, I didn't want to make the filler neck fully stainless steel too, so I figured the Ni-Terne would be good enough.

 

[xetura]

Any updates on this? Pretty sure I'll be doing something similar in the future with a stainless tank. Seems to tuck up there pretty well.

 

[WCBlueSky]

I moved houses, had another kid, got another car to fix, etc. so this got put on the back burner, but I'm starting to work on it again. I fished captive nuts into the body following LandCruiserPhil, but it was way too much trouble. If I could do it over I'd just use Nutserts (aka rivet nuts) like everyone else.

I also made the straps today out of 1" x 1/8" flat bar

 

[xetura]

I moved houses, had another kid, got another car to fix, etc. so this got put on the back burner, but I'm starting to work on it again. I fished captive nuts into the body following LandCruiserPhil, but it was way too much trouble. If I could do it over I'd just use Nutserts (aka rivet nuts) like everyone else.

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I also made the straps today out of 1" x 1/8" flat bar

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Life happens! Glad to see you're still working on it. Looking good. I just picked up a slightly used tank for $40 today after getting inspiration from your findings.

 

[Rifleman]

WCBlueSky I like your idea of using a Camero tank, and it fits so nice in that space,​

I really wanted to do something like what you're doing, But i started thinking about all the work it's going to take to fab up a fill pipe to fill the extra tank, mounting brackets, skid plate, and hooking up a transfer pump,​

I'm sorry to say that it's not as easy now as it use to be for me to crawl around underneath my truck due to my age and bad knees, so i ended up going a different route, i built a swing out carrier to carry an extra 10 gallons of gas, not nearly as nice as your 18 gallon tank idea though,​

I do have to say one nice thing about my swing out, i don't have to handle the cans to fill my gas tank, I can use my safety siphon and fill my tank while the cans are still mounted in the carrier​

 

[WCBlueSky]

@Rifleman nice swingout! I totally agree this project is a ton of work and working under the truck is not the most fun. We carry up to 20 gallons of fuel on the roof rack, but with another kid we want the space on top for other things. Planning to finish this project over the winter.