Any difference between the nikki that came stock on the 79 and the nikkis that came stock on the 81-85s?

 

Yes, I can not tell you what the differences are, but they are not the same. I have a 83 carb and it has notable differences visually, The core might be the same though.

 

yes, they look the same, but basically everything changes a little.
the big change is the 81-85 carb top, its smaller and flows better. the middle and lower are basically the same, but passages move so you can't mix and match

 

So... it's a little more complicated than that

SA carbs (79-80) and FB carbs (81-85) are fairly similar with a few minor changes across the years and regions. The most notable differences you see by looking at them are:
- Different arrangement of smog equipment (SA carbs have one or two solenoids on the carb itself)
- The SA carb air horn (the name for the top third of the carb) has larger openings for the primary venturis and in some older threads is referred to as flowing decently better. In reality the slightly smaller FB air horn flows completely adequate, and actually works a little better for boost since it partially shelters the air bleeds.
- SA carbs have three idle tuning screws, FB carbs have two. On an SA the big flat head screw on the t-body is the air screw, the smaller philips below it is the mixture, and by the throttle is the idle speed screw. On an FB you only have mixture and idle speed (same locations).
- Various changes in smog equipment
- SA carbs have less stuff on the throttle shafts and are layed out a little differently (neither is really superior in my opinion for a stock application)
- The t-bodies, phenolic spacers, and intakes will also not perfectly line up if you swap around things. They will physically bolt together, but you'll have a bunch of smog circuits criss-crossed and deadheaded if you do so. Again, really just depends on what you're goal is with the setup.

As far as things that you can't see, well there's a number of jet changes, and some differences in circuitry, but that's not really too important unless you're doing some more involved mods.

There's also a couple versions of the FB carb, and those parts can be swapped around without too much issue. A number of SA parts can go on an FB carb, although you've got to be more careful to ensure everything will still get where it's supposed to.


Did I over complicate it or was that about what you were looking for? There's a fair amount more detail to go into if there's something specific you're wondering about.

 

Nice write up! I think you covered the majority of it.