Hey guys,

I am about to rebuild a set of 3 screw SU's I bought, and was looking over all the emissions hoses tonight after I did the timing chain and some other stuff. I was wondering if there are any writeups about this swap and either using or not using the emissions. It would be good to get rid of all the hoses and stuff. Anything will help, hopefully theres a link, or someone can quickly point out what to do with the tubes and holes. Thanks guys, and I have searched but not finding any direct answers yet.

-Joe

On mt '73 240 , I am running SUs , actually the engine is a '82 ZX . The only emission related item on the engine is the PVC valve. That's it. In addition to the round tops you should run a '70--72 air cleaner . It will have the proper places to connect the float overflow lines and the valve cover vent hose , plus the fresh air supply hose to the fuel tank. Also don't forget to plug the outlet that supplied clean air to the air pump , I simply used a cork from the inside. The air cleaner has air horns that are tuned , by there length , for performance at the factory . You will need the linkage that runs between the carbs from the 240 . The 260 part is too short. Where the vacuum lines were attached to the balance tube that are no longer needed , just plug them . Brass plugs are available at Home Depot or most hardware stores. You need the thicker spacer that installs between the carb and the intake manifold also. You stated that you were going to rebuild the 3 screws. Be careful what you use to clean the carbs especially around the locating ''pins'' that align the dome to the carb base. This in turn aligns the vacuum piston and needle to the nozzle. This is a critical alignment. One more thing , don't mix the parts from one car to another especially the domes and vacuum pistons and nozzles. These are fitted at the factory for that one carburetor. Hope this helps . Gary

Thanks for some info. I have both ZTherapy videos and have watched them 3 times, and will one more time and take good notes. I have the carbs, with linkage and air cleaner from the 71 240. Which hole is the one that I plug that supplies the clean air to the air pump? Also, the back of the air cleaner that bolts up to the SUs has different hose alignments than the 260 flat top air cleaner... kinda wierd.

Heres a video of the car with flat tops really out of tune... (I turned the car off and opened the air cleaner and the butterflys were open... thats not good right?) I did a bunch of the tune up stuff before, and now I'm going to rebuild the carbs.

http://beta.yousendit.com/transfer.php?action=download&ufid=FC7591270AB7FD92

I am in the process of the same change out and there seems to be a ton of hoses, vacuum lines, etc. It looks like there is another thread from earlier this month talking about the same topic. This seems to be a pretty common swap, but I too have not been able to find much good info on the topic. I got my old flat tops off yesterday and am ready to install the round tops. the biggest issue so far was the antifreeze. Now I will need to add a coolant line to circumvent the carb connections. I think the best way is to view a few photos online. I did not change the manifold or balance tube as they both(72 and 73) had the same markings.

I will have to take a look at the air pump connection.

Bill