The Stovebolt Site Forums The Parking Lot '60-'66 Trucks 21 Gallon Side Fill LMC Rear Fuel Tank Install

65 C10 SBSS

I figured it was time to remove the 18 gallon factory installed fire bomb from behind the rear seat and move all the fuel way out back.

So, a 21 gallon LMC (blazer style) side fill fuel tank is in and plumbed and grounded. Just driving around to get the Cab Bomb down to 1/8th or so, so I can man handle it out and make the final two hook ups....one fuel line at the engine pump and one wire to the gas gauge on the dash.

I didn't take photos as I went along but its an almost easy fit and pretty much a no brainer....just a lot of gunk in the face working on it from underneath.

First, needed a fuel neck. Went with stainless steel boat deck filler, 1.5" spout and a keyed cap so the average bored teenage kleptomaniac will be confounded and steal someone else's cap.

Filler sits flush and even though on top of the fender, not really noticeable. Just drill a 1 7/8 hole and three smaller ones for #10 stainless machine screws and lock nuts.

http://i.imgur.com/DCgeSPk.jpg

Close up....it even reminds me what its for....

http://i.imgur.com/4VFQ7Ad.jpg

From the underside....the temp install. I will fill it the first time and if no leaks, I'll replace the zip ties with metal banding and make a bracket for my boat deck vent so it points down (The boat deck vent is attached to the 1/2" port on the DS of the tank since the cap is not vented.) The tank had two other 5/16" return lines, one DS, one PS. I'm not running electric pump so don't need them....rather than cap them, I simply plumed them together with Moroso Aluminum fuel line above the forward lip and fastened it to the underside of the bed so it don't vibrate. The two returns tied together can't be seen once the tank is up and in.

Temp install because.....the tank fill neck is 1 3/8".....the filler cap neck is 1 1/2". I plumbed it 1 1/2 inches and double clamped the large hose at the tank. If it leaks, I'll add a short length of reducer pipe and a 1 3/8 filler hose at the horizontal section......But if it don't leak, I ain't getting back under there for a long time....its a snug fit to tighten clamps.

http://i.imgur.com/SB9HkDh.jpg

On the DS, about 3.5" clearance to the factory bend tail pipe....plenty.

[img]http://i.imgur.com/rxir3oj.jpg[/img]

As you can see, after removal of the spare tire (the bottom of which was 13" down from the bottom side of the bed sill), and removing all the spare tire hardware, and trimming 1" out of the bed sill from left to right (but still plenty strong to hold a load in the bed).....the bottom of the tank is just about the same 13 inches down from the sill. Essentially, it hangs no lower than the spare did, and the hardware with the spare was actually a full 16" down from the sill. The spare or its hardware never drug and I don't expect the tank will....but I ain't crazy bagged dragging the frame tearing out the door sill plates and slashing tires on cut away fender wells low either. (No offence to low riders even though you look silly stuck in the parking lot with one side down on a broken bag. )

http://i.imgur.com/nMslBhv.jpg

And plenty of clearance to reinstall the hitch.....I had to rtv the hitch washers in place since the tank blocks access to the heads of the bolts and wiggling the hitch into place on loose bolts and washers was an exercise in profanity. But with a lock washer on each, the nuts snugged down and the bolts don't turn. If I ever have to take it off, I might have to make access ports for the bolt heads in the lower portion of the frame.....later, later, my back hurts right now.

http://i.imgur.com/0iiOUwF.jpg

Wish me luck....another day or so and I should be able to make the final connections and yank the Bomb Tank!

Good luck

Looks like a clean installation.

A couple questions for you:

1.0 How about a picture from the side, about 20 feet away from the truck? Can you see the tank hanging down below the bed?

2.0 What keeps water from getting into the vent? Since it is located inside the rear fender it will be inundated with water off of the tire.

John

1. no more than ya could see thespare from the side (ya gotta peek between fender and tire to see it for the most part)

2. lik stated, we'll leak check then hang it vent down or tuck itbehind the fill pipe...no water will get in...or at least less water than you pump in each fill up from contaminated ground tanks...no different than running a differental vent...open air, small hole, pick a good spot and no worries.


ill do pics soon.

Wow, great job. I wish I had tried that tank. It looks to be the same as the Blazer kit I bought but on my 3/4 ton 4x4 it required some brackets be welded in. Also the tank straps would only fit on one side. Your frame appears to be much different so I will assume it's the difference between the 3/4 and 1/2 ton.

I haven't figured out how I was going to make the filler line but like your idea. I don't have a short bed so the plan was to come up in the wheel well as you did, just will be on the inside of the bed. Here are some pics of the install. Not sure if they will work...
http://i193.photobucket.com/albums/z269/Yroundriden/65%20GMC/20150104_172627.jpg

Your frame looks quite similar to mine though your tank appears much further forward than mine. Mine is back against the rear cross brace where the frame levels out. Yours appears to be forward on the upslope. Wondering if your Diff pumpkin will strike the tank in its current position.

The tanks are the same, yours and mine.

I did not notch the frame....merely cold bent a lip in the DS frame rail to add a bit of clearance for installing the filler band clamps. Simple job with an adjustable wrench and bent the lip 1" in from the edge and about 1" to either side of the filler neck. However, Had I installed the rubber fill hose first, no bend was likely to be needed.

Sliding the tank rearward all the way to the rear cross brace accomplished three things...

1 No interference with the diff.

2 Got the fill neck far enough back for easier access around the bed sill (the rear one that bolts bed to frame - its the one I notched to raise the tank as high as it would go)

3. Got the 1/2" dia vent tube out from under the same bed sill....just enough rear of the sill to install the vent hose and not have the entire assembly inside the sill and butting up against the bolt that holds the bed to frame on the DS side.

Excellent

John

Hooking it all up today. Cab bomb is finally down below 1/8 tank so I can man handle it out. Cold as a witches hootie in a brass bra though. Probably work in stages with warm up breaks even though I'm in the garage!

Will report back today if it all works out or at least as soon as my hands warm up enough to type.

Its in. 7 gallon fill for initial road and leak testing.

Gauge works. (0-30 ohm unit comes with the tank for the 60-66 trucks)

http://i.imgur.com/yccD8eE.jpg

No leaks noted. I'll run a couple half tanks and then a full one for leak checks but so far so good.

A bit of extra weight in the back helps smooth out the ride some too. It'll be interesting to feel a difference with a full tank.

The vent works great. The tank will accept fuel as fast as I can pour it from the big cans. Should be fine at the pump and no more shaking the truck to burp the Cab Bomb so it will fill up and no more stink in the cab either plus plenty of room.

Got a spring clean up to do behind the seat and start figuring out some sort of storage set up....but I won't mention the possibility of hunting weapons storage back there cause it causes some folks to get spastic, so ignore the present rifle rack and pistol vault....pretend its fishing pole and tackle storage or something else safe that doesn't cause you to tremble.

http://i.imgur.com/UTZ0toY.jpg

Photos of the #3 and #4 vents that were not needed for this install.....linked together with Moroso Aluminum Fuel Line and secured to the bed wood against vibration. (I've found caps to rot, leak and fall off....this seemed better.)

http://i.imgur.com/8j1SU0W.jpg

http://i.imgur.com/BfECkYV.jpg

Promised photos on a stock ride height 65 C10....pretty well unnoticeable from most angles.

http://i.imgur.com/SDOXvm7.jpg

http://i.imgur.com/6M31pXD.jpg

http://i.imgur.com/7FiYQ4H.jpg

http://i.imgur.com/JboBUOS.jpg

http://i.imgur.com/2SsDET3.jpg

And the 2 year old reproduction 18 gallon Cab Bomb out and sealed and ready to moved along.

http://i.imgur.com/UZMKQBM.jpg

http://i.imgur.com/9RL3KfV.jpg

http://i.imgur.com/NhHHW8M.jpg

Overall a really nice installation. Thanks for documenting too.

You're welcome.

ya that looks great. Mine would not fit further back due to clearing the bed, maybe something to do with the long bed. I also had to cut 1/2" off the fill tube just to get it to clear the frame so there must have been some differences in the tanks or frame. I was very careful to clear the axle diff, I did have to relocated the brake line though. Yours came out great. I'll post more when I get the bed back off after paint.

Thanks for posting the photos. You did a great job with the installation.

I'd be concerned about how low the tank hangs, but then again maybe I am just to conservative? http://i645.photobucket.com/albums/...%20Truck%20Stuff/6M31pXD_zpsa3b1cc53.jpg

like I said. hangs same as the spare tire and thats been no trouble for 50 years. folks that should worry are on bags with butchered suspensions, frames and fenderwells

cool. love to see it

Excellent work guys, I wissed out and went with a fuel cell. John, I see your truck on every c10 forum on the web. Beautiful ride.

Success. Tank takes fuel from the fastest pumps without a hichup or splash back and no more burping it to get it full. No leaks. Rides smooth with a full tank too!

Here is the basic step by step.

1. Remove spare and spare hanger bar and bolts.

2. Grind rivet heads at frame rails and remove spare tire bracket.

3. Cut 1" notch in rear bed mount sill from inside frame rail to inside frame rail.

4. Test fit tank positioned as far to the rear as it will go. (LMC 21 Gallon kit) I had to cold bend the DS top frame rail a bit to clearance the filler neck.

5. I had to bend up the corners of the rear most frame cross brace as they touched the upper rear corners of the tank. Once bent up slightly, the tank slid fully rearward, its rear lip on the underside of the rear cross brace but no where else did the cross brace touch the tank. This positioning moved the DS center (1/2") vent tube out from under the bed cross sill that I notched. The vent then sat to the rear of the bed cross sill instead of under it, allowing me to attach a vent hose with no interference from the bed bolt that go's into the frame on the DS rear.

6. Mark and Drill 2 mounting holes in the underside of the frame rails for the DS and PS flange of the tank. Remove tank.

7. Install 3/8" bolts with lock washers under the bolt heads. Keeps the heads from turning as you snug up the nuts from the underside (tank eliminates access to the heads of these mounting bolts unless you add holes in the side of the frame to get a wrench on the bolt heads.)

8. Using a roll of new metal fuel line and some rubber hose and 4 band clamps, tie the two unneeded forward vent/return tubes together. Route the tube/line up and around the front of the tank.

9. Install a length of vent hose to the 1/2" vent on the center DS of the tank with a band clamp.

10. Install a length of 1.5" filler hose on the tank with two band clamps. (Remember, my fender fill neck is 1.5" and the tank filler neck is 1.375". Two clamps at the tank prevented leaks. If you prefer make the transition from 1.5" to 1.3" by installing a steel Exhaust reducer near the tank. ROL makes them in 1.5 to 1.375" transition. Then you can install that 1.5" hose at the fender filler and a length of 1.375 hose at the tank neck. But so far, mine has no leaks as two clamps seems to have cinched the 1.5" filler hose to the 1.375 tank filler neck quite nicely.)

11. Install the sending unit, its gasket and wire it up. Install a length of fuel filler hose to the sending unit with a band clamp.

12. Install the tank, fishing the filler/vent tubes up and between frame and bed. Then tighten up the four mounting bolts securing tank to frame. Tank lip is on the bottom edges of the DS and PS frame and on the bottom edge of the rearmost frame cross brace. Top of the tank does NOT touch the notched bed sill. On the DS side mount the ends of the aluminum tank straps on the tank flange mounting bolts. Use fender washers under the nuts.

13. Drill the PS outside face of the frame rail for the j-hooks, install and snug up the bolts to pull the tank straps tight across the bottom of the tank from DS to PS side. Use padding under the straps if you like. I did not and have no squeaks.

14. Ground the tank to the frame.

15. Fish the sending wire up into the cab and attach with solder to the original gas gauge line at the DS rear of the cab/door.

16. Pick a spot on the fender and drill a hole for the boat deck filler. Drill holes for the attaching screws. I used a stainless deck filler and #10 stainless screws and lock nuts and flat washers.

17. Install a 1.5" to 1.5" 90 degree exhaust elbow in the tank filler hose with a band clamp.

18. Notch the sheet metal of the DS bed (near the rear fender brace rod) as needed to clearance the 90 degree bend making the path to the tank at least level (i.e. don't have the elbow low so gas has to run up hill to the tank filler neck.) There is enough room to do this getting a level run and not removing the rear most fender brace.

19. Install a length of 1.5" filler hose between the top of the 90 degree elbow and the fender filler neck with band clamps

20. Install your choice of vent in the hose from the vent line of the tank, place the vent high in the fender well and point it down to keep out water. You can also place the vent behind the filler hose to keep water off.

21. Under the truck, use some screw in clips to secure the line you installed (to link the two unneeded returns together) up against the bottom of the bed....prevents vibration of the line.

22. Fish the new metal fuel line from tank to pump. Hook up both ends. Secure along the length of the inner PS frame using a combination of the factory fuel line clips and new clips every 12" or so to prevent fuel line vibration/cracking.

23. Put in 5 gallons of gas, check for leaks. Start the truck. Check for leaks. Go drive. Check for leaks. Fill up, drive, check for leaks.

24. Ensure dash gauge is working.

25. Remove cab bomb tank from behind seat and sell cheep or give it away.

26. Enjoy