SU twin carbs need adjustment /troubleshooting information

[Ainthot]

Hi guys. Hoping someone can help me out here. I have searched pretty heavily for information on this carb setup but most of what I have found is for an MG style SU. According to the previous owner, this is an L20 shortblock and an SSS cylinder head. That is all I can recall about it as I purchased it a few years ago and forgot about it til recently. I am hoping that someone can give me more information on on to properly set these carbs up.

 

The car will fire and run when cold with the choke on. When its warm the car will idle very low and eventually die(roughly 400rpm). Opening the throttle blades whatsoever kills the engine. I just cant seem to find much information on setting these being that I am not certain how to adjust the air/fuel or float assemblies on it. Muchless the linkage. Here are a few pictures of what I am working with if anyone has some information on it. Thanks for your time.

 

While I have an extensive history in fabrication and restoration work, I do not build Datsuns so I am unfamiliar with some of the terms you use for certain parts on them. So please clarify for me. Thanks again.

 

http://i583.photobucket.com/albums/ss275/ainthot/Datun%20510/IMG_0251.jpg

http://i583.photobucket.com/albums/ss275/ainthot/Datun%20510/IMG_0252.jpg

http://i583.photobucket.com/albums/ss275/ainthot/Datun%20510/IMG_0253.jpg

[datzenmike]

Here's a good place to start includes the flat top style you and I have. How to de-smog them etc. Some links to other pages. Nissan uses the Hitachi 'S U' carb which are based on the British Skinner's Union carbs. The only parts that are compatible are the jets so stick to the Hitachi ones.

 

 

http://www.jetlink.net/~okayfine/sutech.html

[wayno]

If the vehicle has been setting for a long time then you need fresh gas though out the system first, are you sure it ran right when you bought it? There are a lot of things that need to be right before you can adjust them. I would suggest you buy a manual, I use "chilton, datsun 1961-72", part # 5790 It discribes how to setup dual SUs, There might be a thread on this procedure in this forum. You should also buy an "air flow meter"

[Ainthot]

So basically he had access to a complete cylinder head for the non US 1.8 and just bolted that on here? Your link is very helpful by the way. Appreciate it.

 

I ran fresh fuel through it. I went as far as checking to make sure the floats were operational and cleaned the needle and seat assembly under the caps. Did not really have any idea where to go from there though. I fired the engine a few years ago and then let the car sit til a few days ago when I felt like doing something with it again. It "did" start it just did not want to run today.

[zerow]

From the pictures you posted, you have the "infamous" tuna can SU carburetors. From what I can tell, the manifold is the later version (K14 casting) with all of the smog junk. My first recommendation is to de-smog the manifold. I posted this pic a long time ago for de-smog procedures:

 

 

The next thing you will want to check is the PCV valve. If it is old or sticking, you are bringing in too much air, and that will cause it to crap out when you crack the throttle.

 

Hope this helps...

[zerow]

Here's a good place to start includes the flat top style you and I have. How to de-smog them etc. Some links to other pages. Nissan uses the Hitachi 'S U' carb which are based on the British Skinner's Union carbs. The only parts that are compatible are the jets so stick to the Hitachi ones.

 

 

http://www.jetlink.net/~okayfine/sutech.html

The jetlink site is awesome, and I have one other one that has helped me with my rebuild:

 

http://www.teglerizer.com/sucarbs/techtip6.htm

[bigdaddy1957@comcast.net]

Steve Eperly at Z-Therapy is the Man that can help you...