I just got a very original 74 260 that hasn't run in a while. I'm looking to make it a Sunday summer driver only. Previous owner started it in '97 and was told it needed carbs. It has the original flat tops on it(which I just took out). I keep reading about changing to early 240 carbs. What do I do about all the vacum lines on the 260? Will all these match to a 240 carb? Is it a straight replacement? Or do I just rebuild these flat tops? Is that an option or a waste of time? It seems Z Barbie know quite a bit about this. Please help.
What about the cooling lines that run through these carbs also? DO I just take them out and cap them. It was an original California car so does it have more emmisions crap then a non California car? Can any of that be removed?
Please excuse my ignorance.

 

You can use the round tops on the same manifold, it breathes better. The 240 manifolds have the coolant lines running through them too to help the heat from the exhaust dissipate. The only vac line is on the fuel bowls for overflow into the air cleaner. You need the linkage between the carbs too.

 

Thanks, I'll try it out.

 

Steve , are you exempt from emissions testing ? If this is the case you can remove all the related vacuum lines and parts. You need to have a vacuum line from the intake manifold port that is just in back of the front SU , and run it to the vacuum pot on the Dist. This is NOT manifold vacuum so it must be from the place I described.
In my opinion messing with the flat tops is a waist of time unless you want COMPLETE original Z for Shows. Another vacuum line is the one to the brake booster.
If you run a '72 or earlier air cleaner then you connect the overflow lines from the SUs float tops to the ports provided on the air cleaner, also the vent hose from the valve cover attaches to the cleaner as well. Incidentally the OEM air cleaner has tuned air horns built in that are vary efficient to smooth the flow of air to the carbs and is a performance item. I use a K&N filter in mine and swear by them. Depending on if you are going to use 4 screw or 3 screw SUs. As to performance they are the same , one of the differences is the three screw has a water jacket in the base. You can block it if you wish. Z Therapy is a good source for these . They sell both and they rebuild them and are better than new . They use roller bearing on the throttle shafts that are triple sealed.
Gary

 

Thats good info. Thanks I'll use it.
Steve