nate_82zx Posted January 15, 2011 Share Posted January 15, 2011 I'm planning a SU swap on my L28E. I have all of the parts now just figuring out my fuel line situation. In the picture I assume the large hose to the right is the fuel feed? What is the smaller hose to the left go to? Heres the picture. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 15, 2011 Share Posted January 15, 2011 Holy Internet Bog In China Batman, never got more than a hose clamp downloaded on that photo before it froze! I see what looks like an SU Dome...and a hose with a fuel clamp on it, but no realy indication of 'left or right' so let's review the hoses on an SU. UNDERNEATH: small 4mm or so hose goes from the float bowl to the main jet. Special flexible hose, don't use regular fuel line here clamped down to fit---it will sideload your jet and make it wear or stick in operation. TOP: 5/16 (8mm) hose with a big nut holding it to the side of the float bowl. This is your fuel feed line. Remove the big hex nut, pull the whole thing off, and make sure the brass screen in there is free and clear or you run lean under load. Top of the Float Bowl: 1/4" (5mm) sometimes this has a barb fitting on it with a hose, other times on early cars this is a nut with a hardline. Float Bowl Vent. The line connects to your air cleaner to allow for no differential pressure issues with the plugged air filter you are running... That's it, and I didn't even get to see the whole photo... By size alone, you should be able to figure it out now... Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 15, 2011 Share Posted January 15, 2011 I take that back, while I was typing, the photo started appearing more completely. From the photo, L to R 5mm line pointing up and stuck inside the second line. That is the float bowl vent. It goes to the air cleaner, or down to the ground by the headers. Mine are zip tied together and go to the gound... 8mm line pointing back with the 5mm line stuffed into it and the hose clamp on it. That is fuel feed. 12mm line on the far right, down low---water line for preheating the carb bases in cold weather to prevent icing and sticking throttles. Originates at the lower casting of the thermostat housing, goes through the manifold, and then round back of the engine where it joins with the heater core 'out' line to return to the pump inlet. This is part of a bypass loop when the engine is cold which helps it warm up quicker. Later carb setups closed this off at 177F... Quote Link to comment Share on other sites More sharing options...
nate_82zx Posted January 15, 2011 Author Share Posted January 15, 2011 Awesome! Exactly what I needed to know. Route them to the ground. Thanks Tony. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 15, 2011 Share Posted January 15, 2011 With the right thread banjo fittings, you can make your own rigid hardlines for that connection. The barb unscrews to a straight thread with washer-seal. That is what the original 69 - 71 JDM cars had on them---no captive emissions for them, just dump any overflow to the ground through steel pipes! Quote Link to comment Share on other sites More sharing options...
nate_82zx Posted January 15, 2011 Author Share Posted January 15, 2011 Ok cool i'll definitely look into that. What about the feed lines? More specifically, I do not have the stock fuel rail. My plan was to run my line from the mechanical pump and use two tee fittings to each inlet, then a regulator on the end before returning it to the tank. I read thats pretty close to how the stock setup was. Quote Link to comment Share on other sites More sharing options...
Tony D Posted January 16, 2011 Share Posted January 16, 2011 Just have the appropriate restrictor so the pump can build pressure and feed the carbs, or better yet a proper backpressure regulator manifold referenced so it slightly raises fuel pressure when vacuum drops to zero at WOT. Quote Link to comment Share on other sites More sharing options...
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