Nova fuel tank replacement
Fixing fuel system problems you might not even know you have
Wayne Scraba - December 01, 2011 10:00 AM
1 Here’s a bird’s eye view of the original tank from our 1969 Nova on the left and a reproduction tank from Classic Industries on the right. Basically, the topsides are identical, aside from the finish, and what appears to be a pair of tooling indentations on the topside (the never-seen side) of the reproduction tank.
2 Flipped over, you can see both tanks are physically identical. If you choose to black out the gas tank (as in our very late production 1969 Nova), here’s the pattern Chevy used. As you can see, it’s not pretty and it’s not consistent. The black out is almost flat black.
3 You can see some carnage to the stock tank. We take responsibility for that one. Some might try to fix this damage, but it’s just not worth it.
4 The one slight difference we can spot is the filler neck. There’s a larger “rib” on the leading edge of the original tank in comparison to the reproduction, but that’s not critical. Keep in mind you can’t see it when the cap is installed, and besides, the entire works is hidden behind the license plate on a Nova.
5 If you choose to keep the tank silver, here’s a technique we’ve found that works successfully on vintage applications: Clear enamel (we use automotive paint, specifically for engines – it’s not affected by gasoline).
6 To apply it, lightly scuff the tank surface (Scotchbrite pads work or fine steel wool). We use metal prep to wash the surface. Once dry, apply several light coats of clear. By the way, you can use the same process to “black out” the tank, if you choose.
7 This is the collection of parts that make up the sending unit and pickup assembly available from Classic Industries. This particular component is for use in 1969 375 to 396 hp applications. For that combination, the pick-up tube size is increased to 3/8-inch. Classic offers replacement pick-up screens (socks) if your set-up still functions, but requires servicing.
8 Here’s a look at a set of original tank straps along with a set of reproductions from Classic Industries. They’re very close in appearance. The originals were obviously blacked out with the tank. As near as we can tell, the black out took place after the tank was installed in the car.
9 What’s with the black insulators? That’s an anti-squeak kit. The strips are installed between the tank straps and the gas tank. Two of the other longer strips mount topside and ditto with the small piece (they sandwich between the tank and the body).
10 This is the hardware used to hold the tank strap in place at the rear of the car. The carriage head fasteners install at the rear, while the two screws install in the leading edge of the tank straps.
11 Here’s our original gas cap. Our plan is to keep this cap, however, replacements are available. Keep in mind some cars require a vented gas cap. Others don’t. You can’t mix and match.
“There are plenty of great quality reproductions out there, and it’s far easier (and far safer) to remove and replace the fuel system pieces.”
Let’s face it. We’re all messing with cars that are 40 or so years old, And those years have a way of deteriorating hardware, even on low mileage vehicles.
One component that is often junk, but you don’t know it, is the gas tank. Think of it for a minute: It’s a vessel designed to hold a relatively volatile commodity. Factor in the chance bad gas (sometimes with a considerable quantity of water in it) was pushed through the tank, and you can imagine the consequences.
Mix in normal temperature variations as well as huge humidity fluctuations in various parts of the country, and you can appreciate the fact tanks don’t last forever. Worse, gas tanks tend to deteriorate from the inside out. That means a tank that looks pretty good on the outside can prove paper thin in any number of spots.
Way back when, the tanks were most likely “terne plated” – a process that, amongst other elements, used lead in the plating process. The terne plating rustproofed the interior and simultaneously protected the gas tank against salt and other corrosion attacks. The result was a gasoline tank that would last the life of the vehicle (of course, the lifetime of vehicle isn’t exactly infinite and no one expected these cars to be treasured four decades later either).
You might also come across a process called “Ni-terne”. Here, the steel used in the tank has been flash coated with nickel prior to the tin/lead coating, which in turn provides an additional layer of protection. Some folks point out that the original terne plating process eventually erodes when exposed to today’s oxygenated fuels. The end result is the fuel system can be damaged by the lead erosion.
But Wait!There’s more
Four or so decades ago, it was standard practice for the manufacturers to install the gas tank at the rear of the car (no secret). Often it was mounted too low. That meant it was susceptible to curb damage from backing up. The truth is more than a few vintage tanks have their fair share of nicks and dents. Our example is no exception.
Holding the tank in place was usually tasked to a pair of rather thin straps. Just like the tank, the straps are located where road debris is almost always a factor. If the tank is rusty, plan on the straps being rusty, too. If the tank was mangled, then there’s a pretty good chance the tank straps are in a similar condition. Sandwiched between the tank and the straps is a pair of thin insulators. There’s also a set of anti-squeak insulators between the tank and the trunk floor. In some cars, figure on corrosion between the insulators and the tank.
Then there’s the hardware that holds the tank and straps in place: In the case of many Chevy (and other GM) tanks, the leading edge (immediately behind the rear axle assembly on the trunk floor) is mounted by way of a loop in the tank straps. Out back, just ahead of the bumper, is where the whole works is bolted in place. In a high-mileage car or one from the salt belt, expect the hardware to be corroded, often beyond use.
Sending units and fuel pickups/fuel strainers were commonly one-piece affairs for GM muscle cars. Big-block cars have larger fuel line sizes, and that includes larger pick-up tubes within the sending unit. Some applications have return lines to the tank while others have fittings for evaporative emissions canisters. Although the sending unit assembly could be serviced, few were. Because of that, plenty of senders — and more importantly, plenty of pick-up socks — are clogged or otherwise damaged.
In some GM muscle cars, the tanks were blacked out. In others, the tanks were simply raw. The truth is, the black out process wasn’t consistent. In the accompanying photos, we’ll show you our vintage tank and tank straps. Both were blacked out, and you can copy the black out pattern for your car if you choose.
So, if something is amiss in the tank assembly, how do you fix it? In a single word — don’t. There are plenty of great quality reproductions out there, and it’s far easier (and far safer) to remove and replace the fuel system pieces. The truth is, we’re not only talking about the safety of the car here folks. We’re discussing your personal safety, too. If anything (tank, straps, hardware or pickup) is suspect, replace it.
For Your Information:
The Parts We Used
This is a list of the various components we used (the pieces listed here are for a 1969 396 Nova). The part numbers are from the Classic Industries catalog.