47-55.1 Fuel tank advice

[51 3600]

Next project on my '51 is fuel system. Tankwise the goal is a rear mounted unit with filler neck up through left rear fender. Since my truck is a 3600 I don't have as much flexibility as the 3100s have. Space is more limited. Pic below shows space dimensions.

Note: bottom of frame rail is wider than top of frame rail. Bottom could be trimmed if necessary, just more work.
Attachment 2168018

I've narrowed my tank searches down to 2 Tanks Inc. possibilities a 53-CG or a 53-CPS. Originally used on 53-54 Chevy cars.

Attachment 2168023 Attachment 2168024

The steel 53-CG measures 29.25" x 21.25" x 8.25"
The poly 53-CPS measures 28.5" x 19.5" 8.5"
Using the poly tank I could get by without trimming the bottom frame rail. In either case I have to move the crossmember farther back but that's just unrivet, move and bolt or weld back in.

I know nothing about poly tanks so could use some advice. Pros & cons. How do you mount a poly tank?

[crossfire84]

Take a look at my build it may help.

[fauXGT]

Just finishing up on this mess. probably 100+ total hours into it.
The tank is early 50's chevy sedan. 18gal from Tanks. EFI ready. Uses stock filler tube.
And I am NOT a pro restorer (stress relief hobby), so a good chunk of the time was thinking about it, and pausing, and thinking about it again.

[51 3600]

Just noticed the pics didn't post. Hope this works.



53-CG


53-CPS

[51 3600]

Originally Posted by crossfire84

Take a look at my build it may help.

Yep, that's what I'm trying to accomplish just as you've done. Can't believe I missed that tank as many times as I've been on the Tanks Inc. website. That's the ideal size.

Couple questions:
Do you have any pics of how you mounted the tank?
At a 10" tank height how low does the tank hang below the frame? I don't have the bed on my truck so I can tell how high or low to place the tank.

[fauXGT]

Yeah. I removed the spare tire cross member and built a structure at the tail so I created much more room. Is a 3100 frame, 6400 cab, and 3600 other parts. The frame was slightly tweaked in the rear once the tire support was removed, so the back structure straightened it. Wanted to make a safety structure between the rear and the the tank, but it still could turn into a Pinto.

[51 3600]

Originally Posted by fauXGT

Just finishing up on this mess. probably 100+ total hours into it.
The tank is early 50's chevy sedan. 18gal from Tanks. EFI ready. Uses stock filler tube.
And I am NOT a pro restorer (stress relief hobby), so a good chunk of the time was thinking about it, and pausing, and thinking about it again.

I have seen your posts of this installation before. Very well done. I don't have your fab skills to build that in-bed filler tube cover. I could build a square box for a cover but that would look really ugly.

What size square tube did you use to build the tank support frame?

[fauXGT]

Varied between .75 to 1.25" squared tubing. I chose different sizes to what would clear the upper bed structure and the rear bed mounting to the frame and the strength needed.
Alot of any custom build is staring....looking....thinking....analizing...and thinking again 15 steps ahead, much like chess.
I have a slightly antiquated welder, no previous metal skills, but a passion to get the result I have envisioned completed.
I guess that makes me a 'hotrodder'.

[crossfire84]

Originally Posted by 51 3600

Yep, that's what I'm trying to accomplish just as you've done. Can't believe I missed that tank as many times as I've been on the Tanks Inc. website. That's the ideal size.

Couple questions:
Do you have any pics of how you mounted the tank?
At a 10" tank height how low does the tank hang below the frame? I don't have the bed on my truck so I can tell how high or low to place the tank.

I will get some pictures this week for you.

[mobileortho]

I used an early mustang tank in my 3600. Fits perfectly between the frame rails. Jay fuel door in the rear fender

[dsraven]

hey mobile, nice to see the truck pics from the no box floor position and see the finer things that make a mechanic like me smile. little things like the exhaust clamp u bolts are installed with the threaded ends pointing up so the poor guy who crawls or works under it doesn't lose the skin off the top of his head, the exhaust is routed out of the way for the fuel tank and not cut off ahead of the axle so oxides in the exhaust don't corrode everything behind that point, the differential cover is accessable without unbolting a bunch of stuff. nice. that fuel door came out pretty sweet too. is it vented?

[whitedog76]

I recently saw someone post that they used a tank from a 95 GM van. Looking at the specs, they are 31x22. They have a 22 gallon and 33 gallon option and are EFI ready.

[mobileortho]

Originally Posted by dsraven

hey mobile, nice to see the truck pics from the no box floor position and see the finer things that make a mechanic like me smile. little things like the exhaust clamp u bolts are installed with the threaded ends pointing up so the poor guy who crawls or works under it doesn't lose the skin off the top of his head, the exhaust is routed out of the way for the fuel tank and not cut off ahead of the axle so oxides in the exhaust don't corrode everything behind that point, the differential cover is accessable without unbolting a bunch of stuff. nice. that fuel door came out pretty sweet too. is it vented?

You know, when guys like me who don’t know what they’re doing get comments from guys like you who do, it really means a lot! Thank you!

[dsraven]

hey, no problem. keep it up and you will be answering questions too.

[51 3600]

Originally Posted by mobileortho

I used an early mustang tank in my 3600. Fits perfectly between the frame rails. Jay fuel door in the rear fender

There's a lot of helpful info in your post. I like the Mustang tank. Would not have thought of using that with the fill neck at center back but it obviously was not that difficult to route it through the fender (looked at your build pics). Tank is shallow too.

Thanks for posting.

[mobileortho]

Originally Posted by 51 3600

There's a lot of helpful info in your post. I like the Mustang tank. Would not have thought of using that with the fill neck at center back but it obviously was not that difficult to route it through the fender (looked at your build pics). Tank is shallow too.

Thanks for posting.

It wasn’t too difficult at all. Glad it was helpful.

[dsraven]

in general, the rearcross member can be removed and placed further forward or back as needed to fit the tank in the available space. I like the idea that fauXGT has with the "rear bumper" tank protector to aid in possible rear end accidents. having done a few propane conversions years back it reminds me of the guidlines for a propane tank install behind the rear axle. they were allowed to hang down as far as an imaginary line drawn from the ground contact point of the rear tire to the low point of the rear bumper, with the load on the vehicle. that said, we could use that same theory to safely install a fuel tank in the rear of our trucks but I would suggest to lower the suspension so it sits on the snubbers and then draw the line for the lowest point. that way if worse came to worse like a flat tire or a broken axle where the wheel comes off, you only have to deal with that problem, not a crushed or leaking fuel tank or a fire as well. on some low slung cars, like corvettes, there are slide blocks on the frame to act as the low points of contact should something like that happen or a curb strike etc. that idea could also be incorporated if desired. something that bolts on would be best in case replacement is necessary or maintenance of something else behind that is required.
when thinking of fuel tank options it is best to think of what other systems will be needing space in the same area and also how routine maintanance will be affected by how things are put together. as a mechanic I can't tell you how many times I have had words under my breath regarding the engineers who designed some things. like why are the hose clamps on the fuel tank put on facing up when you can't get at them due to the box being in the way, why is the panhard bar placed right in front of the rear axle cover, why does the interior of the car have to come out just to get at the shock bolts, and so on. anyway, it is good to think about room for the exhaust routing so as not to heat up the tank, the filler opening on the tank needs to be accessible so the filler hose has room to route, if you plan to haul anything at all then a bed floor filler location isn't the best option, a low filler location may only allow a very slow fill without kicking off the fuel filler handle, there will need to be room to access things like shock absorber bolts for maintenance and, as shown, there is a need to think of rear end crash posibilities and/or dragging for low slung tanks. it is great to see guys getting those tanks out of the cab though, thats step 1. the tanks with the filer on the side lend themselves to being able to be fitted higher in the frame simply because there is no need to allow room for the filler hose on top of the tank, unless you are going with a bed floor filler. there also needs to be room between the bed structure and the frame for the filler tube to fit in. one other thing to think of is the rubber hose to use as fuel will eat a simple rubber hose like a rad hose. fuel filler hose is different stuff but is available at local hydraulic hose shops usually. a high quality band clamp should also be used at the connections and some hose shops will sell you a gear clamp with an extra slipper section between the hose and the slotted sections of the clamp. this keeps the soft hose from being squashed up through the slots on the band section of a regular style hose clamp. a ground strap between the filler neck and the tank is also a great idea because static charge can build up between the parts and when the filler handle is removed from the truck fill tube a spark can be generated. newer vehicles have these ground straps installed and we don't think twice about it. there are warnings at fill stations about filling gas cans on the ground instead of in the box of your truck, airplanes and fuel tankers etc are mandated to use a dedicated grounding strap from the filler tank to the vehicle for this reason. just something that only takes a minute to do and something to think about if you want to add that to your build. I know I have, you don't even notice it.
anyway,
just some thoughts.

[dsraven]

one other thing to think about for the mounting of the tank is to consider how the tank was originally made to be mounted. some tanks, like the old mustang tank, are made to sit on the floor of the car's trunk and screw down to the floor through the pinch weld of the tank. other are made to be hung with straps located in the recessed parts of the tank top and bottom. obviously, if the tank was made to sit on the pinch weld then that is fine to mount that way but if the tank was made to be hung on straps then hanging it by the flange for the pinch weld may cause the tank to develop a leak at some point in the future. as well, screwing through the pinch weld area for a tank that wasn[t made for that can/will cause a leak. the mounting straps and upper mounting brackets would be available from a wrecker or possibly new ones could be purchased online for the donor vehicle of the tank you are planning to use in these cases. the straps will fit the tank well and keep it from moving fore to aft as well as keeping it from falling out. if planning on fuel injection then purchasing a tank rhat was originally plumbed for fuel injection may save you some hassle. remember to leave a bit of extra fuel line looped, or have a connection outside the footprint of the tank mounting area or have access to the fuel line area so if/when the tank needs to come out the fuel line can be disconnected prior to that without removing the box or a bunch of other things.
again, just spitballing some ideas for anybody doing a fuel tank choice/mounting

[51 3600]

Originally Posted by dsraven

remember to leave a bit of extra fuel line looped, or have a connection outside the footprint of the tank mounting area or have access to the fuel line area so if/when the tank needs to come out the fuel line can be disconnected prior to that without removing the box or a bunch of other things.

Excellent idea that I hadn't thought of but will incorporate.

Decided to got with this tank and have removed the rear crossmember to accommodate it.


Next question. Plan to use original AD filler neck mounted in the rear fender. Original has vent tube which tank does not have, venting being accomplished through fuel pump. Can I, as I assume I can, just block off the neck vent? No problems? Also, filler neck is 1 3/8" tube. Who has fittings to go from 1 3/8" to 2" neck on the tank (hose, tube, reducers, etc.). Tanks Inc. has some but not for 1 3/8".

[leegreen]

try a 1949-51 ford car tank (shoebox ford)
someone gave me one it fits nicely between the frame rails and is quite shallow.
They are available new. Not sure if you can get one setup for in tank pump.



just held in with a ratchet strap in picture but that was final location.



I wish I'd put that filler down lower. I want to run a locking gas cap and any rain that hits the key slot is going to drip into the tank.

ps: that is a c10 frame but the rails are the same width

[fauXGT]

Originally Posted by dsraven

in general, the rearcross member can be removed and placed further forward or back as needed to fit the tank in the available space. I like the idea that fauXGT has with the "rear bumper" tank protector to aid in possible rear end accidents. having done a few propane conversions years back it reminds me of the guidlines for a propane tank install behind the rear axle. they were allowed to hang down as far as an imaginary line drawn from the ground contact point of the rear tire to the low point of the rear bumper, with the load on the vehicle. that said, we could use that same theory to safely install a fuel tank in the rear of our trucks but I would suggest to lower the suspension so it sits on the snubbers and then draw the line for the lowest point. that way if worse came to worse like a flat tire or a broken axle where the wheel comes off, you only have to deal with that problem, not a crushed or leaking fuel tank or a fire as well. on some low slung cars, like corvettes, there are slide blocks on the frame to act as the low points of contact should something like that happen or a curb strike etc. that idea could also be incorporated if desired. something that bolts on would be best in case replacement is necessary or maintenance of something else behind that is required.
when thinking of fuel tank options it is best to think of what other systems will be needing space in the same area and also how routine maintanance will be affected by how things are put together. as a mechanic I can't tell you how many times I have had words under my breath regarding the engineers who designed some things. like why are the hose clamps on the fuel tank put on facing up when you can't get at them due to the box being in the way, why is the panhard bar placed right in front of the rear axle cover, why does the interior of the car have to come out just to get at the shock bolts, and so on. anyway, it is good to think about room for the exhaust routing so as not to heat up the tank, the filler opening on the tank needs to be accessible so the filler hose has room to route, if you plan to haul anything at all then a bed floor filler location isn't the best option, a low filler location may only allow a very slow fill without kicking off the fuel filler handle, there will need to be room to access things like shock absorber bolts for maintenance and, as shown, there is a need to think of rear end crash posibilities and/or dragging for low slung tanks. it is great to see guys getting those tanks out of the cab though, thats step 1. the tanks with the filer on the side lend themselves to being able to be fitted higher in the frame simply because there is no need to allow room for the filler hose on top of the tank, unless you are going with a bed floor filler. there also needs to be room between the bed structure and the frame for the filler tube to fit in. one other thing to think of is the rubber hose to use as fuel will eat a simple rubber hose like a rad hose. fuel filler hose is different stuff but is available at local hydraulic hose shops usually. a high quality band clamp should also be used at the connections and some hose shops will sell you a gear clamp with an extra slipper section between the hose and the slotted sections of the clamp. this keeps the soft hose from being squashed up through the slots on the band section of a regular style hose clamp. a ground strap between the filler neck and the tank is also a great idea because static charge can build up between the parts and when the filler handle is removed from the truck fill tube a spark can be generated. newer vehicles have these ground straps installed and we don't think twice about it. there are warnings at fill stations about filling gas cans on the ground instead of in the box of your truck, airplanes and fuel tankers etc are mandated to use a dedicated grounding strap from the filler tank to the vehicle for this reason. just something that only takes a minute to do and something to think about if you want to add that to your build. I know I have, you don't even notice it.
anyway,
just some thoughts.

Got the C-4 Vette rear suspension in and when I removed the spare tire cross member for the tank the frame sprung to the inside. Got the port-power out and pushed it almost 2" outward to square it up. The frame had been hit or something. Had to create a rear support to push the frame back out so hence the extra structure to the rear was made.
I probably would have still done it even if the frame was square being visions of 'Pinto's' were dancing in my head with the tank there.

[dsraven]

one big thing to do on any resto is to get the frame on stands all by itself and do some dimension checks for square, sag and straightness. this should really be done before anything else gets started because the frame is the foundation for everything else to sit on. next up would be to replace any and all body mounts as they are usually shot. I usually mark each cross member at it's middle and then run a laser or stringline down from fore to aft center marks. all those in between should line up. it is important also to use a tape measure that doesn't stretch or that has a loose btaxket on the end, you gotta be taking the dimensions from the same place on each corner.