The GM G-body LS swap presents some unique obstacles that are becoming easier to circumvent. The fuel system is one such obstacle that can be nearly a bolt-on project now. The G-body almost lends itself to the fuel system retrofit with all of the current parts available. Some customizing is required with the fuel lines, but still a very straight forward project with the proper tooling.
seen here is the flexible fuel line that runs behind the engine and is attached to the corvette fuel rail while using the truck style coil bracket and coils.
The LS engine requires a fuel pressure of 58 PSI and most fuel supply lines are an AN6 size. The fuel line shown in the photos was hand formed using stainless steel seemless tubing (purchased locally from Old Dog Street Rods) and stainless steel AN6 fittings (37 degree flare parts purchased from McMaster Carr). There is a need for some type of pressure regulation to make the constant 58 PSI possible. The easiest way, and perhaps the cheapest is to use a C5 corvette filter/regulator (part # WIX 33737 available at NAPA, O’Reily’s, or even Amazon.com). This style filter/regulator will also require adapters for the GM style quick disconnect ends to convert over to AN6 ends (my choice for adapters were Russell 644123, 644113, & 640940). There is a return line required and depending on which style intake determines the length of the return line. Since I am using the car style intake and the corvette style filter/regulator, this return line runs only from the filter back to the tank.
The G-body already has a factory fuel tank that is set up for fuel injection (Turbo Monte Carlo tanks and Buick Grand National / T-type tanks). The sending unit is also a stock application, however, the fuel pump will need to be changed out to keep up with the fuel supply demand. I used the Holley 12-914 fuel pump, which is a 255lph style pump, but others can be used (such as part # F20000169 found on Amazon.com). The fuel return line and the vent line on the sending unit also will need to be changed – see the MalibuRacing.com forum for an in-depth discussion on the sending unit.
The Holley 12-914 is a high quality part. There is no guessing if it’s a remanufactured part.This was a Fuel tank from a 90K GN. I painted it with POR 15 under the straps as these are known to collect moisture and rust. The fuel supply line was 3/8 inch and the return line and the fuel vent line are both the old return line size. The tank was virtually like new when I was finished with it.
Next, an easy way to distribute the fuel to the injectors. Since I chose the FAST 90mm intake, it was very convenient to use a corvette style fuel rail ($20.00 craigslist), but other styles may be used depending on the fuel demands of the engine. When using the truck style coil packs and the truck coil brackets, this style fuel rail will not fit due to the 90 degree bend at the quick disconnect point on the driver’s side. It is worth entertaining the idea of moving the coils to a remote location, or altering the coil bracket, but both options will likely result in a bare stock valve cover (which looks silly in my opinion), or purchasing aftermarket valve covers (which I may do at a later date for aesthetics). I simply removed the 90 degree bend section of the fuel rail and used an aircraft/industrial grade compression fitting from Swagelok to adapt to an AN6 size inlet (part # SS-600-6-6AN).
The fuel rail tube was bent at a 90 degree turn exiting outboard and down with a GM quick disconnect end. I cut the tube with a small tube cutter from Lowes and removed the tack welded supports. The Swagelok compression fitting (part # SS-600-6-6AN) was then tightened according to the installation instructions and checked with a special Swagelok gauge (part # MS-IG-468). This fitting is rated to 10,000 psi – it should be ok…Swagelok will also build anyone a custom length stainless steel braided fluid line. They come with a pressure certification and a leak check sign off. The length may vary, but mine was 38 inches long and the part # is: ss-xt6ta6fu-38The flexible fuel line was run into a bulkhead fitting that is secured to the frame rail. Again, all done in stainless steel for anti corrosion purposes. When ordering the line from Swagelok, make certain that you ask for part # SS-600-8-003 to be added to the flexible line (previous part#)This is the Stainless Steel 3/8 inch tubing I custom bent to run along the inner channel of the passenger side frame rail. This view is forward-looking aft. The brackets are stainless steel with matching hardware.The C5 Corvette filter/ regulator can be easily obtained at most parts stores. Its imperative that this filter gets a good ground. The adapters for the GM style quick disconnects convert over to AN6. The Fuel lines were bent to match up. Now a normal over the counter filter can be changed like a daily driver. The filter was mounted on the frame rail near the rear passenger wheel.My advice is to build your fuel system before the body is on the frame, but I was able to build this WHILE the body was on the frame. The most difficult part of this fuel system was getting the supply and return line to match up to the filter without rubbing on each other or contacting any sharp surfaces. They were both ran like the stock lines and using stock gm fasteners to keep them separated throughout the run. It is difficult to see all angles from this view, but both lines are suspended without rubbing on the frame, not rubbing on each of the other, and not drooping below the frame.As stated, this was the most difficult part of the fuel system build. Working these bent lines between the body and the frame to where they meet up with the fuel tank lines will make your arms hurt and scratch the bottom of the trunk floor. I copied the shape of the stock lines, but the filter/regulator make them slightly different in shape. Seen here is the connection of the Supply line and the return line with a AN6 to AN6 union and a AN6 to AN5 union respectively. The tank vent line was another return line from another car and is not attached to a 4th Gen. Camaro style fuel vent yet.The final product was a clean, maintenance friendly, safe fuel system that is nicely tucked up tight to the car much like a factory system.
More of this fuel system can be seen in the book “GM G-Body Performance Projects 1978-1988” by Joe Hinds. As the owner of Bulldawg Muscle Cars, Joe is a great resource for the G-body community. Check out his website and definitely check out his soon to be released book! (Amazon.com)
Lots of things are coming together on the HotRodRegal. Up and coming posts will include new parts, suspension tweaks, all kinds of wires, shiny stuff and hunting more Baer!!!
