simply the fact you changed the carbs will cause it to fail doesn't matter if the exhaust is cleaner than the air. Also the motor doesn't belong in the car. You might be able to get through, but it's still not legal.

CA has lame laws about these things, I know I thought propane is cleaner than petrol, so that should be easy to get through the smog refree... nope. if it doesn't have a CARB # for your engine application, too bad no matter how clean they won't pass it.

Putting a different engine in a vehicle isn't ok either, nor is using a different transmission, or changing anything.

but those things only matter if someone is doing the smog check properly.

I don't mean to #### in your cheereo's, but if the motor is from a similar vehicle of the same make or newer, it is legal in california. Most smog ref's are not datsun expert's either. so if the motor plate staes it has twin carb's, and the tech see's two carb's with vacuum lines running to the correct places, Air box with correct PCV sytem, Egr in working order, a cat and working exhaust, ect.. who is he to say it's not correct. I am not planning on making every thing chromed out and pretty, I am going to make it LOOK factory. So if it looks like a duck, quacks like a duck, and smells like a duck... it just might be a Datsun.

Awesome project. There is a B110 with stock KA24E in Bay Area that does 13-second 1/4. It is stock except for twin webers.

By the way, 1980 model would be a B310 "Datsun 210", model years 1979-1982 in USA. B210 was "Datsun B-210", 1974-1978 models years in USA. The B310 has more classic style, while the B210 has more '70s type styling. Both have their own charm.

You may get away with doing this.

However the 720 is a truck and putting that engine in a vehicle that is not a truck is the problem.

it's not as simple as it conforms 100% to the newer standard, you can't legally put a truck engine, head, transmission, or carb in a vehicle that is not a truck.

I'm not trying to be a difficult, I've had experience here and CA law makes it very difficult to do legally. Even the Z engine would be a problem since the vehicle it belongs in is significantly heavier vehicle, the only legal swap would be swapping in an A15.

I'm not saying your wrong, but I work as a tech, I've been around car dealers my whole life, and have seen many swaps that you say are not legal done. A big block in a 80's malibu, Grand National engine in a chevy truck, Corvette engine in a El Camino ect.. all have papers and pass a smog.
There are many loopholes and if you use them in the correct order, many things not LEGAL can be done. It's not my fault they don't catch everything, but it's to my benefit. haha

Like I said, we just have to be smart about it!

Well...I have my doubts the referee will pass the vehicle! ...I'm glad there are people who are corruptible so my car will pass a SMOG Test ONLY!!