Fuel Rail for SU Carbs - Help!

[zerow]

I have a set of 38mm SU carbs that I'm putting on my L20B. I have the original fuel rail that came with the carbs, and I was able to get my hands on a "short" 240Z fuel rail. The original has the obvious plumbing, with connections for each carb and it terminates at the rear carb. I seem to have read or heard somewhere that some people were using a 240Z fuel rail for their 38mm SUs. How does that work when the 240Z rail has the outlets for the carbs AND plumbing that goes back to the tank? Any insight or suggestions would be appreciated!

[DISLEXICDIME]

i just run fuel hose and brass t's but i am getting ready to cut a 240 z rail down and weld it

[zerow]

i just run fuel hose and brass t's but i am getting ready to cut a 240 z rail down and weld it

 

My fuel rail is the correct length for a 4 cylinder motor, I just have no idea where to plumb the runoff fuel that is going to come back through the return pipe. I just don't want to unnecessarily cut a perfect setup for an old Z car just for my own sick amusement. The 610's evap setup is at the rear of the car, otherwise I would try to send the fuel back to the tank via some pre-existing plumbing.

[Farmer]

having somewhat the same issue as you, but I dont have any thing to start out with. But got some plans in the making. Just got to find money to do it.

 

Larry

[zerow]

having somewhat the same issue as you, but I dont have any thing to start out with. But got some plans in the making. Just got to find money to do it.

 

Larry

 

Larry, I can only imagine that I would have to run a line back to the tank, but then how does this pressurized fuel/vapor, which is inevitable, vent out? My evap is literally behind the rear seat, not a nice place for fuel vapor to be accumulating. I just don't know. Not that I am out to do everything that I read/hear about, but if this Z fuel rail is some magic thing, I just want to know how to make it work. Otherwise I will just run the stock looking plumbing and keep the Z fuel rail for another ride.

BTW: Where in Grants Pass are you located, I have family up there.

[Farmer]

I lived right in down town, off of 4th street.

 

If you look at this picture of my Su's This is how I was told to hook them up. This is going in a 620

 

 

The two silver metal tubes on the bottom go to the black canister up front which is for vapor. (which I wont be using) Then you can see both fuel intake make with red tap. And if you look close, there is another nipple just to the right of the right fuel one. That is suppose to be the overflow outlet. That should be on a direct path back to the fuel tank.

Not sure how the fuel lines run on your car, but the 620 have I believe three separate lines, one supply and two returns. One return runs with the supply. And the other line in on the exhaust side that the Black canister connects to. Some one can correct me if Im wrong.

The 620 stock fuel rail on newer years have the supply and return built in, but have only one outlet. So if you have a stock z rail with return and two outlets, i would use that one. Hope this somewhat helps.

 

Larry

[ggzilla]

Twin Carb setups -- at least the early to mid-70s -- did not use a fuel return line. With a 3 lb pump it is not needed.

 

Just use regular fuel line, with a T-fitting to split off hoses to each carb.

 

The overflow outlets go down to the ground. Normally, no fuel ever comes out of there.

 

As far as I'm aware Datsun didn't fit return lines with carbs except around 1980 for emission control reasons. The technical reason is that the underhood temps were so high, they added a fuel return to keep the fuel cool (not because of pressure reasons)

[ggzilla]

I take that back about the Fuel Return.

I'm looking at my 1972 Datsun 510 catalog now.

 

* The two silver lines in Farmer's photo are marked as "fuel overflow tubes".

* The two fittings with red tape (in the photo) are the fuel inlets

* there is a "fuel return" hose on the rear carb. I can't see exactly where it goes.

 

But other models, like the B110 Twin Hitachis, didn't use a fuel return line. So you can probably just cap it.

[zerow]

I lived right in down town, off of 4th street.

 

If you look at this picture of my Su's This is how I was told to hook them up. This is going in a 620

 

 

The two silver metal tubes on the bottom go to the black canister up front which is for vapor. (which I wont be using) Then you can see both fuel intake make with red tap. And if you look close, there is another nipple just to the right of the right fuel one. That is suppose to be the overflow outlet. That should be on a direct path back to the fuel tank.

Not sure how the fuel lines run on your car, but the 620 have I believe three separate lines, one supply and two returns. One return runs with the supply. And the other line in on the exhaust side that the Black canister connects to. Some one can correct me if Im wrong.

The 620 stock fuel rail on newer years have the supply and return built in, but have only one outlet. So if you have a stock z rail with return and two outlets, i would use that one. Hope this somewhat helps.

 

Larry

 

My cousin lives off of NE Scoville Road. Never been to his new place, but I was going to see him before continuing on to Canby. Now that I am unemployed, the Canby trip has been "canned".

 

I will have to check for any return lines, I don't recall there being any, but I am not sure. I like the overflow tubes you have, where did you get them? Nice setup on your SUs as well, I'm going for polished domes and brushed float bowls. If I don't find any return lines, I'll just go with the stock looking fuel rail and keep the Z rail for swap meet fodder.