So you’re sold on doing an EFI conversion, perhaps one of the easy self-learning systems profiled elsewhere in this issue. Pretty much any company marketing conversions will have you taken care of with everything needed from the engine to the fuel system upgrades, but what about the fuel tank?
For our baffle we just grabbed...
For our baffle we just grabbed a scrap piece of sheetmetal left over from a failed experiment on a previous project. If you need some, hit the metal scrap yard for something cheap; this needs to be functional, not pretty. Working with advice from the fuel experts at Aeromotive for the dimensions, our grid lays out a box with an 8x9 floor and 5-inch high walls.
While you can technically run an EFI system with any factory fuel tank, the problem is that older tanks, typically pre-1980s, don’t feature any sort of baffling or sump; it’s just a big open chamber for the fuel to slosh around in. Such is the case with the fuel tank in Project EcoNova, our ’76 Nova project car and its LS3 E-Rod conversion. With the low pressure and flow associated with mechanical fuel pumps, that’s not too much of a problem for daily driving situations. EFI pumps, however, flow much more fuel at around 10 times the pressure—something our Nova’s E-Rod conversion would demand. If the tank is below half to a third full, just exiting a freeway ramp could be enough to create a fuel starvation issue that could damage the pump, or even the engine. If you’re planning to do any sort of performance driving like autocross or open track (that’s us!), forget about it, you absolutely need a baffle of some sort to keep fuel around the pump.
" …the problem is that older tanks, typically pre-1980s, don’t feature any sort of baffling or sump…
"
There are some great ready-to-go EFI-prepped tanks on the market, but they tend to be pricey, and model-specific applications will only be the usual suspects, Camaros and Mustangs and so on. So what do you do if you’ve got a project with no direct-fit option—such as a ’76 Nova—and you’d rather avoid a universal fuel cell? No worries, we’ve got the solution. There’s a quick, easy, and cheap way to prep just about any tank for EFI. Even with a killer pump like the new Aeromotive 340, we still came in around $350 total. Not bad at all considering we didn’t reuse anything from the car, and we finished it off in a day. Better yet, all the work is on the top and inside the tank so it retains its stock looks, and with an in-tank pump there’s no telltale whine either.
The first problem with vintage...
The first problem with vintage tanks is the size of the fuel sending unit; there’s barely enough room to slide in an electric pump, much less the full sending unit assembly. Our pump of choice is Aeromotive’s brand-new 340, which is a direct drop-in for most standard in-tank pumps.
Note of Caution:
We recommend using a new reproduction tank that has never been filled with fuel of any kind for this mod. If you choose to reuse an old tank, do not attempt to cut or weld on it until it has been professionally cleansed and rendered inert. Some fuel tank or radiator resto shops can handle this, but ask first and tell them what you’re planning to do. Don’t try to clean it yourself, and don’t trust advice on the Internet—old fuel tanks can, and do, explode!
" No worries, we’ve got the solution. There’s a quick, easy, and cheap way to prep just about any tank for EFI.
"
We’re not steady enough to...
We’re not steady enough to trace a perfect line freehand, so we used the Miller’s wheel guide with the 375 X-Treme plasma cutter to remove the corners of the grid so our box can fold up. A grinder and a cut-off wheel can handle the job as well.
To get inside to build our...
To get inside to build our baffle, we first have to remove part of the top for access. It’s best to plan the size of your baffle beforehand and only cut as much off as necessary. We cut out a roughly 9x10-inch piece from our new Classic Industries fuel tank with Miller Electric’s Spectrum 375 X-Treme plasma cutter. The 375 is a great tool to have around, and with dual-voltage capability it can be used in virtually any location.
If you have access to a metal...
If you have access to a metal break, that will help get the flaps started, but won’t allow them to fold all the way up. We used a piece of 1x1-square tube to bend over and start our edge, then went to work with a hammer and dolly.
Don’t be afraid to manhandle...
Don’t be afraid to manhandle it into shape; once we had a good bend going with the dolly we forced the flaps into place, and then went back with the hammer and dolly to square up the edges again.
We weren’t sure what gauge...
We weren’t sure what gauge our scrap sheetmetal was, but we keep one of Miller Electric’s gauge checkers in our toolbox for just such an occasion. Useful little thing! The thickness is needed to set the voltage and wire feed speed on our Millermatic 211 Autoset MIG.
We’re not total newbies when...
We’re not total newbies when it comes to MIG welding, but we’re not exactly good either. The Millermatic 211’s Auto-Set fills the void nicely since all you have to do is select the wire gauge and the gauge of the steel you’re welding, and the machine calculates the rest for you. It’s even switchable from 240V to 120V just by swapping the plugs. We have to say, it’s really the king of home garage welders.
It’s not the prettiest thing...
It’s not the prettiest thing we’ve ever built, but it’s very functional. Lucky for us this beauty will be hidden inside the tank.
While the idea is to hold...
While the idea is to hold a column of fuel around the pump, we still need it to be able to drain back slowly and equalize with the rest of the tank. One ⅜-inch hole drilled on each side of the box is ideal per Aeromotive’s recommendation. Avoid drilling the front and rear of the box, and never the bottom.
Here’s what years of fabrication...
Here’s what years of fabrication experience can do for you; Stroud had finished welding and ground down the bead before we were even able to finish building the sending unit.
In the tank we positioned...
In the tank we positioned the box mostly to accommodate the position of our stock pickup assembly. We drilled four ¼-inch holes in the bottom to rosette weld the box to the tank floor.
Bodie Stroud of Bodie Stroud...
Bodie Stroud of Bodie Stroud Industries volunteered to help us weld in a mounting flange for reassembly, mostly because he wanted to try out our new Millermatic 211 welder!
Here’s the mounting flange....
Here’s the mounting flange. It’s really as simple as it looks; we just cut out a 1-inch-wide perimeter from heavy 12-gauge scrap sheet, bent it to match the missing piece, then welded it in under the lip of the tank.
Here’s the stock sending unit...
Here’s the stock sending unit for ’75-79 Novas (and ’76-81 Camaros) from Classic Industries. These are available cheaply and will work well for our EFI conversion; plus, we have the benefit of retaining the stock fuel-level gauge.
Here’s the assembled sending...
Here’s the assembled sending unit; we bent our pick-up tube over 90 degrees to clear the trunk pan then used a short piece of ⅜-inch hose to attach the Aeromotive pump. There’s not much slosh in the fuel box, so to hold the pump in place we just went with a hose clamp to snug it up to the return line. We’ll fess up if it doesn’t work.
Step one is to remove the...
Step one is to remove the filter from the pickup tube; a little squeeze and tug with a pair of pliers and it’ll slide right off. This will now be our return line.
Here’s how it will look when...
Here’s how it will look when buttoned back up. If we need to service the pump, the panel and assembly will come out together. As for sealing it, we’ll be cutting a custom gasket from bulk material to sandwich between the panels and apply a little fuel-resistant sealer. We may also top it off with a second perimeter ring and secure everything with screws and wide washers placed every 1.5 inches just to be extra safe.
Cars equipped with A/C have...
Cars equipped with A/C have two lines, but this non-A/C unit only has one. The circle where the line would have been is clearly visible though, so we drilled a 27/64-inch hole to slide a ⅜-inch piece of tube through for our new pickup. We’ll solder or TIG this in place later.
By lucky chance, our stock...
By lucky chance, our stock pickup is oriented perfectly; away from the pump pickup and toward a wall of the box at a glancing angle.