Datsun Roadster Carb Parts from Rallye Enterprises, Ltd.



90 Degree

180 Degree

(also known as customer response #32..."What do you mean 90 degree, 180 degree?")

The 1600 38mm (1 1/2") and the 2000 46mm (1 3/4") carburetors each come in two styles. One is designed for "90 degree nozzles" the other is designed for "180 degree nozzles". Whether or not the two types still have the nozzle type that they left the factory with is anybody's guess. Mechanics, car owners and parts counter people don't always know the differences, and the murky "official" parts book doesn't help much. Originally the 65-67 1600 and the 67 and some 68 2000's came with the 90 degree nozzles. A lot of cars have been altered.

The term "90 degree" or "180 degree" refers to the relationship between the fuel pipe fitting on the nozzle, and the threaded hole for the linkage screw. If you turn your nozzle upside down you can see that they are either directly across from each other (180) or at a right angle to each other (90). You can also just look at these pictures. The correct float bowl for the 90 degree nozzle has a fuel outlet that points horizontally at the throttle body portion of the carburetor. The 180 degree type float bowl has a fuel outlet that points downward at a 45 degree angle, towards the air cleaner. (Your float bowl may or may not have the drain plugs shown on the bowls above.)

The biggest problem with the SU carbs on the roadster isn't the carbs themselves, it's what has been done to them since they left the factory. Parts from both types are mixed together and the result is something that either doesn't work right, is prone to fire, or both.

The metering nozzle, the black plastic part you see go up and down when you pull your choke, has to be able to go up and down smoothly, and return completely with no drag. When you lift the piston inside the carb up just a tiny bit and let go, it should drop down with a noticeable click or thump. It should sound the same with the choke cable pulled or not pulled. If you pull the choke cable, then push it in, you shouldn't be able to touch the nozzle with your finger and have it pop up the rest of the way, it should already be up.

If the wrong nozzle is used for the particular carburetor, the linkage piece that moves it will not match and can lead to binding. If the fuel pipe has been replaced with the wrong one, or by one out of some other material, this can also lead to binding or worse, fire. This small tube, is manufactured from extremely high quality heat resistant neoprene, which is not normal fuel line. It is also moulded so that it has NO STRESS on it when it is installed. Granted, the original moulded ones are relatively expensive, if you don't figure in the costs of a possible fire. If you are attempting to use a substitute type of line it has to be out of a material that has a HIGH resistance to hardening from the heat, and a HIGH resistance to cracking from motion. If I had a nickel for everytime someone brought a car to me after it had been "professionally" tuned up only to find it was running horribly because the choke stuck the next time it was used due to stiff fuel pipes...

A sticking nozzle can also be caused by a bent needle or a metering nozzle that is not centered. (That's a whole other subject!)

If it was safe and workable to use 30 cents worth of vacuum line, Nissan would have done it. It isn't, and they didn't. When you get a fuel leak it goes right on the exhaust manifold. I hate repairing burned roadsters, and I hate having to buy one that can't be repaired.

Fire can also be a possibility due to improper length (or missing) fuel overflow tubes. Basically you want your fuel overflows that connect to the top of the float bowls to run down below the exhaust manifold. You can use the original long metal tubes or use the shorties with a piece of fuel line attached and routed down away from the exhaust.

What we wanted to do with this page is at least show you what float bowl goes with what fuel pipe and nozzle type. From this you can determine if your car is a hodgepodge of mismatched parts.

2000 90 Degree Nozzle Parts Situation...

The 90 degree nozzles for the 2000 come in a "front carb" and a "rear carb" version. The 1600 90 degree nozzles are the same front and back. One of the 2000 90 degree nozzles is getting extremely difficult to find. Usually you have to buy two of the one that is available and have someone very careful and patient unpin the brass shaft and reuse your old lower plastic part. If this is the case the kit description will say "To Modify Nozzles". If we have the F and R nozzles the kit description will say so.

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Datsun SPL311 SRL311 Carb Parts from Rallye Enterprises, Ltd.