Below is a scanned image of the dual fuel rail arrangement on the Pre-HE Jaguar V-12 engine.
Note the small diameter dual fuel rails, two cold start injectors and two pressure regulators. The fuel has four different paths through the two fuel rails and pressure regulators back to the fuel tank. In a hot start condition the fuel will take the path of least resistance and bypass entire sets of injectors. Finally, in a heat soak condition after shutdown, the small diameter, long winding fuel rails collect a significant amount of heat from the engine. This results in fuel boiling in the rails and incurring vapor lock even if the fuel rail pressure has been maintained.
Photographed below is a picture of my redesigned fuel rail. (see fuel rail fabrication on another link on this website).
The rail is brazed (not soldered). The center pipe is for support only; fuel goes in one side and out the other. This one direction self-purging design ensured that any fuel vapors would be cleared out the moment the fuel pump started and pressured the fuel rail.
Note that the fuel rail is larger in diameter than the original rail, therefore, in order to clear the throttle bell crank, the fuel injector hoses have to be shortened. The exact hose length is contained in the fuel rail fabrication link of this website.
The custom fabricated fuel rail was chrome plated by Paul's Chrome in Evans City, Pennsylvania.
