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Q about SU fuel line routing..


datsunlover

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Ok, sorry for being ignorant... I just don't know alot about carbs. I'm trying to figure out how to hook up the fuel lines to my twin SU's;

Obviously the line coming from the pump goes to the outer-most inlet on the bowl. What do I do about the other inlet/outlet beside it?!? It's just a straight through line into the float bowl.. I was thinking I should run these back to the tank via the return line, but a friend of mine says NO :shock: they are just a vent and I should run a line out of the engine bay and just dump under the car somewhere.. if I return them to the tank, the tank could presurize back through the line and cause problems. What's the deal here? Can someone enlighten me?

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Thanks for the link to the pics man.. that helps me out, but Im still a little confused on the vacum line routing...What's that big line coming out of the middle of the intakes and going under them? If you could post a vacum diagram that would be great. Thanks

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Just wondering what kind of carbs you have, the early ones or the late ones.

 

The vaccuum line you are refering to is the crank case vent ( left in front of the block)

 

If you need some manual shop tell me, I have an Haynes and another one with no name that I could sell to you for little.

Dayz

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Well, I might take you up on that offer.. I have the FSM for my car, but seeing as it's for a 75 it says nothing about carbs. I think I'll get it together, but it'll be a little while before I can get to it. This stupid winter thing won't get lost, so I'm in 'hurry up and wait' mode for a little while. ANd Im off to school in two weeks for april and may, so time on the Z will be limited for the next little while :( Oh well. I'll get back from school, and it'll be summer. Then I can throw all these parts on (that I've been hiding away..) and DRIVE the stinkin thing!

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Bringing thos post back, because I have another question about these carbs;

 

Here is what I am planing to do. Use the stock (75 280z) fuel line from the pump to the engine bay. (do I need that 'fuel damper' with carbs?) At the engine, this feed line splits into 3; one towards the firewall, one towards the rad, one out towards the intake. I was thinking of feeding the carbs with the first two, and using the last one (pointing towards the intake) unto a fuel presure guage, then to the stock return line back to the tank. I think this will work.. but what do you ppl think? Is this dangerous or not a good plan?

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Uhh I think you need to look at those fuel lines again.. One is the fuel from the tank. the other is a fuel return, and the third?...uh maybe a vent line for the charcoal canister???...I can't remember off hand..

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Ok I have to clarify this: I am talking about the fuel feed line that wraps around the front of the valve cover. (it's actually a feed and return line running together on a couple brackets) About half way down the other side of the valve cover, it becomes the stock FI line, and does all those crazy u-turns and twists (to get to the injectors, presure thingy, and then out to a return) BUT just as it splits all up, there is a piece that is like a "T" fitting, and it basicaly splits the fuel line into 3. (one goes towards the rear, one towards the front, and one outwards) It is all the SAME fuel line. I just figured I could use it to feed both carbs, and go through a presure guage before going to a return. Does this make more sence now? I just don't know if it's a 'safe' way to do things...

 

Oh, I'm still wondering about that fuel 'damper'.. it's above the stock fuel pump, in line.. do I need it? Or can I take it out of the system?

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