Before installing the new Rock Valley stainless steel fuel tank we measured the depth of the tank and adjusted the length of the new Classic Instruments floatless fuel gauge sending unit before installing the unit in the tank. As of this writing, the floatless sending units are not available in an ohm range that would render our original gas gauge accurate. Because of that, we opted to mount a new Classic Instruments gas gauge in a traditional cluster under the dash. The floatless sender bolts up to the standard five-bolt flange, however if you have an original ’36-56 Ford gas tank they have a six-bolt pattern. The senders come in a several ohm ranges, check with Classic Instruments for your application.

The Aeromotive fuel pump was installed by Rock Valley so we began the plumbing to the fuel pump plate on top of the tank. Speaking of plumbing, our approach was to run hard lines for a majority of the fuel lines under the car, then using Aeromotive fittings we adapted to braided stainless steel lines for a flex connection to the fuel tank and the freshly installed Holley carburetor and Aeromotive fuel filter. The braided line up front starts at the Aeromotive inline fuel filter, making servicing the unit very easy. By using the flex line connection at the gas tank we did all the plumbing on top of the tank prior to installation, and then simply connected the flex lines to the hard lines after the tank was in place. This makes it simple to remove the gas tank in the future should the need arise.

Installing the new hard fuel lines involved using a pre-bent feed line sourced from Inline Tube while we fabricated our own return line from steel tubing. A flare to AN-6 adapter took us down to the braided hose and then the final connections were made. The stock filler tube was installed to the new Rock Valley tank using a new piece of fuel hose. It is important to use a piece of new fuel hose on this connection as the new hose is able to handle the modern gasoline blends without deteriorating.

The new tank is held in place with stainless steel straps supplied with the Rock Valley tank. When we did the test-fit it became obvious the fuel pump fittings were hitting the floor brace. A small cut-out was made in the brace and since we did not penetrate the interior floor there was no need to do anything else. A quick squirt of black paint prevented future rust and we were done with that small modification.

With the mechanical portion of the job out of the way we turned our attention to providing electrical power to our new fuel pump and gas gauge. The gas gauge has a long pigtail with a plug and since we decided to use an independent, underdash, Classic Instruments fuel gauge we routed the wiring through the car and passed the wire through the floor board using a rubber grommet in the newly drilled hole.

The fuel pump was wired in similar fashion and the supplied relay was wired in and then the power was routed under the carpet rearward to the fuel pump, also passing through the floor board with a rubber grommet.

A double check of all connections and it was time to add some fuel to the new gas tank. A few gallons would be enough to supply the pump and test the system. With the ignition key on the Classic Instruments fuel gauge needle indicating we had fuel in the tank, and the Aeromotive in-tank pump was singing its happy song as it delivered the Aeromotive-regulated 3 psi of gasoline to our new Holley carb. It is best to have one person under the car and another operating the key for this first test, that way should you discover a leak the power can quickly be turned off, limiting any spill or danger. As it turned out our plumbing was leak-free and with a steady supply of fuel to the Holley carb the engine fired to life. Certain that all systems were working well, we filled the tank with some premium gas and enjoyed hitting the road knowing there was no chance of fuel-related problems for a long time to come.

Rock Valley Antique Auto Parts
Route 72 & Rothwell Rd
Box 352
Stillman Valley
IL  61084
Classic Instruments
1299 M-75 South
P.O. Box 411
Boyne City
MI  49712
Inline Tube
15066 Technology Drive
Shelby Township
MI  48315
Holley/Earl’s Performance Plumbing
7805 Barton Street
KS  66214