Rock Valley will fabricate...
Rock Valley will fabricate just about any size or shape gas tank you might need, and they've built tens of thousands of them over the past 30 years.
A gas tank is one of those things everyone needs for their truck. Overlooking low capacity, the main problem with the stock gas tank in most classic pickups is it's usually mounted in the cab, and that means it's dangerous. Remember in 1963 when a sect of Buddhist monks poured gasoline over one of their own and then he lit himself on fire? Not a pretty picture, but it's pretty much the same scenario for anyone unfortunate enough to get trapped in an older truck where the gas tank behind the seat ruptured in an accident, or the owner is a careless smoker. Moving on to a more pleasant aspect is the improved range one achieves for their pickup after they have installed a higher-capacity gas tank.
In the case of '55-59 GMC and Chevy trucks where the stock gas tank holds only 18 gallons it's easy to make an improvement with the installation of a custom aftermarket gas tank manufactured for their truck. This is all well and good for classic truck owners with a popular brand, but what about the people that own a unique example? In the case of CCT contributing editor Eric Geisert and his '41 Willys pickup project he had to design a custom gas tank from scratch to fill his needs.
This kind of undertaking is no problem for an advanced fabricator, but what about the folks who have the will, but not all of the skills? Eric found the perfect solution to the problem by making a quick phone call to Rock Valley Antique Auto Parts in Stillman Valley, Illinois. In business since 1971, the company began building stainless steel gas tanks in 1981 when they re-created a gas tank for a '34 Ford passenger car. Since then they've built tens of thousands of gas tanks for nearly every fitment imaginable. This includes boats, planes, cars, scooters, and military applications. Though now mainly known for their line of custom stainless steel gas tanks, their business also supplies all sorts of fabricated parts. This runs the gamut from battery boxes, running boards, and bumper brackets, to dashboards; and their inventory exceeds 8,000 parts for Fords and Chevys built between 1928 and 1976.
Everybody starts with a drawing...
Everybody starts with a drawing of what they want. This is the illustration Eric made for a custom-fit stainless steel tank to be installed under the bed of his '41 Willys pickup.
Rock Valley advises the home builder to construct a cardboard mock-up of a tank and then fit it to the space they intend to have the real one occupy. That way they can figure out how the rest of the truck's parts, such as the exhaust, rearend, and crossmembers, might interact with where they want the tank located.
Additionally, to get a custom tank made, one has to supply Rock Valley with a blueprint (drawing) of what they need. It should include the height, width, and length of the tank (the formula H x W x L x .004329 will yield the tank's fuel capacity) plus where the filler neck, vent, roll-over valve, fuel pick-up, FI pump (if needed) and, if you have it, the radius measurement of the corners (Rock Valley will do that for you if you don't know what it should be). You'll also need to tell them what kind of gauges you'll be running as the mounts for the electrical senders are different between the different gauge manufacturers and you'll need to indicate the tank's orientation such as front and top.
Once they receive your drawing they look at it to see if you missed anything and how feasible the construction is. They'll call or fax you with any questions and, when they're satisfied with what it will look like, they'll send you their drawing of your tank to confirm everything. Once you give the OK, the tank will be made to spec and you'll soon be down the road. The following photos illustrate just how involved the process of building a gas tank is ... going from a pile of raw stainless steel materials to a custom addition that you designed for your classic truck.
Once Rock Valley knows the...
Once Rock Valley knows the dimensions of each piece of the tank, they can begin to shear the 14-gauge stainless steel used in the construction of the tank.
Rock Valley also designs the...
Rock Valley also designs the tank's internal baffles that help control the weight shifting caused by gasoline sloshing around while driving.
The top and bottom pieces...
The top and bottom pieces of the tank are also cut on a 10-foot shear. For some of the smaller pieces requiring a radius, a high-speed bandsaw with a stainless steel blade is used.
This is the die set used to...
This is the die set used to punch the hole for the sending unit.
Once the sending unit hole...
Once the sending unit hole is punched, four small mounting holes are punched around its edge.
After the appropriate number...
After the appropriate number of holes are punched, all of the pieces that make up the new tank, including the internal baffles, await assembly.
Next, the pieces move to the...
Next, the pieces move to the press where a special die has been made to create the length-wise radius found in the lower section of the tank. Adding the radius to the bottom section of our tank also creates the front and rear of our tank, too.
The top piece of the gas tank...
The top piece of the gas tank is below the bottom section in this photo. With all of the pieces completed, assembly can now begin.
The first parts to be tack...
The first parts to be tack welded in place are the end pieces. A section of stainless steel is also temporarily added to both the front and back section of the bottom piece to help keep the edge straight while being tack welded.
The internal baffles are ...
The internal baffles are next,...
... which are secured to the...
... which are secured to the bottom piece of the tank with small tabs for extra bracing.
The internal baffles are next,...
The internal baffles are next, which are secured to the bottom piece of the tank with small tabs for extra bracing.
Next, the fuel pickup tube...
Next, the fuel pickup tube is installed.
After the sending unit reinforcement...
After the sending unit reinforcement plate is spot-welded in place, the mounting holes are drilled and tapped.
If the truck is intended to...
If the truck is intended to use fuel injection, this is when the brace for the TPI pump is added. Eric's will run a four-barrel carb, so this piece isn't needed.
The tank can now be tacked...
The tank can now be tacked together before the final steps are taken.
The filler neck is next, and...
The filler neck is next, and its location has been spelled out on the work order.
The vent/roll-over bung (which...
The vent/roll-over bung (which shuts off the fuel flow in the event of a roll-over) is added at this point.
The finish welding on all...
The finish welding on all the seams can now take place. Once done, the edges and welds are deburred and ground smooth.
Each tank is pressure-tested...
Each tank is pressure-tested before it leaves Rock Valley to ensure there aren't any leaks, or bad smells.
Here's the space at the rear...
Here's the space at the rear of the Willys S-10 chassis where Eric is going to install the tank. Luckily, there's plenty of room for the tank so he wasn't limited too much by space.
We mocked up the tank using...
We mocked up the tank using a pair of jack stands. Note that the sender is installed to ensure we leave adequate room for it below the bed floor.
A framework was fabricated...
A framework was fabricated to support the top circumference of the tank. Tie-downs are being used in place of the tank straps to check fitment before the tank straps are bent and cut to fit.
With the tank straps fabricated,...
With the tank straps fabricated, the tank is now installed and ready for plumbing.
At the front of the tank,...
At the front of the tank, Eric welded a pair of 5/16-inch studs for the tank straps to attach.
At the rear, Eric used a T-bolt...
At the rear, Eric used a T-bolt and bent the strap around it, similar to an OEM application. Here, the strap is bent to fit but has yet to receive a 1/4-inch fastener to clamp the bolt firmly in place to ensure that the strap doesn't stretch under pressure.
Here's a look at the tank...
Here's a look at the tank strap once it's been bent to conform to the shape of the tank. The extended "tail" on the right will be trimmed to fit, but illustrates the extra length Rock Valley includes in their kits.
To wrap up the tank installation,...
To wrap up the tank installation, we mounted an Air Ride Technologies billet locking gas cap from their Precision Coachworks line of products. The bung on the backside of the cap will attach to the fuel tank's filler neck via a rubber hose.