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| Fuel Line Mod Improves Starting & Driveability https://www.slantsix.org/forum/viewtopic.php?f=19&t=15778 |
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| Author: | SlantSixDan [ Sun Jan 15, 2006 7:28 pm ] |
| Post subject: | Fuel Line Mod Improves Starting & Driveability |
Remove the metal line that runs from the fuel pump to the carburetor and throw it away. Install a 5/16" IV-flare-to-5/16"-hose-barb brass fitting in the fuel pump outlet and another in the carb inlet. These fittings used to be available from Dorman, but that company appear to have discontinued them. For the fuel pump outlet you need a 90° swivel fitting, 5/16" inverted flare by 5/16" hose barb: an Edelmann № 822550, or this elbow From Holley. You need another of these 90° fittings or elbows for the carb fuel inlet on carbs with front-entry fuel inlets (Carter BBS & BBD, Holley 1945 and 2280, amongst others). For the carb fuel inlet on carbs with side-entry fuel inlets (Holley 1920, Stromberg W & WW, etc.), you need a 180° (straight) fitting: 5/16" inverted flare by 5/16" hose barb such as an Edelmann № 721550 or if you can't get one of those, then this one will work. Between these fittings, run a length of 5/16" I.D. fuel injection hose marked SAE 30R9, not the less heat-resistant old-fashioned 30R7 stuff that doesn't do well with modern gas formulations over time. Be sure to get fuel injection hose clamps, too. This line runs vertically up from the fuel pump, over the valve cover, and across to the carburetor. Make sure to leave enough slack in this hose so that you can easily remove the valve cover from underneath the hose when it comes time to adjust the valves. The fuel filter (with a metal can, please; the plastic ones sometimes don't do well with current gas formulations) gets installed vertically so it's right behind the alternator. This keeps it away from heat and the alternator fan cools it down further. Much better than the stock location where it gets heated up by the exhaust manifold! With this setup, a lot of the bitchy hot and cold start problems disappear, because you're no longer boiling fuel in that metal line when you shut off the engine. Another good step to combat the tendency of hot weather to aggravate fuel-related starting and idling issues is to install a vapour-return system. It uses a 3-nipple fuel filter (Wix № 33054 or NAPA Gold № 3054, Purolator№ F20030); the 3rd is ¼" and has an 0.060" orifice to prevent bleeding off useful fuel pressure. You run a new vapour hose from that 3rd fitting all the way back to the fuel tank. Note that some race sanctioning bodies prohibit flexible fuel lines of certain types or longer than certain lengths as a part of the tech regulations, so as always, if you're building a race car, check the regs before you build or modify your fuel system. Want to discuss this mod? The discussion thread is here. |
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