HJy. I am here in California, US. Here the emission laws are more strict than in Connecticut, I guess my car (s) had more devices than yours(your's is federal emissions vrs mine being Californian(really F&^%K*&^D up), so I might talk about stuff you do not have, but all is very similar ,it's all good.
You have the :
`Catalic converter
`EGR system
`PCV system(positive cranckcase vent
system)
`Air system(air pump, valves, etc)
About the catalic, get rid off it, no need for it no more
About the EGR system, the valve(EGRvalve) is bolted onto a plate in the intake manifold, and this valve is conected to a little thermal valve(hooked on to the engine block, works under water temp, to open or close the EGR valve) which itself is conected to manifold vaccum, the valve(thermal) blocks vacum from the manifold onto the EGR valve untill the water temp is as desired by the manufacturers, then only the port opens and manifold vacumm is felt by the EGR valve directly. Get rid of the EGR valve, take it out of the car and throw it away. Cover the EGR base on the manifold with a metal plate cut to size, using a gasket in between.
If you check your Datsun manual, you will see that american intake manifolds have what is called a EGR passage, the EGR valve and other crap is bolted onto this plate, (also the PVC valve, and the small pipe connecting the exhaust manifold to this area, next to the EGR valve.)The best thing to do is to get rid off all this "EGR passage plate", and just put a plate in place, metal plate cut to fit, with a EGR passage gasket off course to seal, and rid your manifold of unnecesary weight and crap. The little pipe that brings exhaust fumes from the exhaust back into combustion through the EGR valve has to go too, and plug shut the exhaust manifold opening for it.
The small thermal valve I talked about before can be left in place, does nothing, just unplug it(rubber hoses) and leave it there alone.
About the PCV system, this system also creates havoc in your engine, designed to stop charged air from the inside of the motor from coming out to the atmosphere. If you think about it, it will always come out , the idea of the emissions is that by recirculating it into the combustion chambers(piston/mix explosion/ignition) this air will become treated. Baloney, the real thing is that you are sending oily air into your carburetor and igniton event in the piston chambers, doing a mess.
As racers do, and as cars where done prior to emissions, disconect the valve cover to carb hose, which, under acceleration is routing oil into your carb,and install a breather filter on the valve cover. Plug shut your carb opening for this hose. The other end, the block vent, also has to be disconnected from the PCV valve and connect it via a hose to another breather, and locate it at the same height or higher(not below) the other breather filter(valver cover), this is a very special point, both have to be at the same height, to have the pulling efect/scavenge effect and vent the motor. The PCV valve is to be thrown away, and plug shut the opening on the manifold. If you get rid of the "EGR passage plate" as mentioned before, the PCV valve opening goes away with it, but if not getting rid of the passage plate, just use a pipe bolt and shut it close off.
I did these operation in my 610, excelent performance, clean carburetor, excelent healthy breathing for the motor.
Your carburetor should be connected with a hose to the distributor,(by the throatle area) the other openings(sometimes the EGR valve, as said before, is connected to the thermal valve, which is then connected to the manifold vacumm, directly on the manifold or to the carb, next to the distributor port in the carb. Some times there is no thermal valve, only the EGR directly conected to the manifold vacumm/or the carb port for the EGR valve next to the distributor port)...in the manifols/and carburetor that will not be used no more should be plugged closed. You can get assorted plugs at any auto store, rubber or plastic caps to plug ports.
About the air system some do have it, it is about the air pump, hoses, and other crap, like the air relief valve, emergency air relief valve, etc, bunch a crap! Disconnect and throw away the air pump, and related hoses.Get rid of the system(you will see these litle valves, like one under the OE air filter, the antibackfire valve, get rid of them, all, and if you have as my car does, close to the thermostat cover, the air valve, where air goes into the cyl head, that one you can take out and plug the opening with a pipe plug, or, in case of just leaving the valve bolted on to the cyl head, just buy a plug(rubber) at an auto store(I used a plug made for the closing of the heater passage in the cooling system, used to eliminate the heater hoses off the cooling system) and plug shut the opening of the valve with this rubber plug. Once the air pump is out, all those hoses away, plug any vacumm ports open in the manifold and the car is ready to breath the way it was intended.
I did all this to my 610, and it runs clean and efficient, and even noticed it runs cooler too, the intake manifold runs cooler due to no more crap(exhaust, cranckcase, and other unnecesary bad stuff put into it, hot air) going inside. Same about your carburetor,no more cranck case hot and oily air going into it. The ventilation of the engine is efficient, no more recirculated stuff, all efficiency.
I can not think of anything else right now, but if I do, I will come back. Ask any questions, make your car healthy, happier, efficient, more reliable and cooler.
Later.__________________