Hello everyone, my '83 is in need of a carb rebuild soon. My questions is, what year nikki carb would be the best to rebuild? I ask because I noticed that my uncle on his '85 12a averages 25+MPG. I on the other hand get between 17-19mpg average with all highway driving. This is after doing a full tune up on the vehicle soon after purchasing it earlier this year. My uncle has a total of 6 Rx7's along with numerous carbs and parts lying around. 2 of the Rx7's are operational while the rest are project/parts cars. Instead of taking out my carb; i was planning to rebuild one of the extras he has lying around that include one from a 79, 83, and 85. I have read that there are changes to mpg from early SA to the FB and revisions were made to the carb and the rat's nest. Should I shoot for rebuilding the 85 as it seems to be the best in MPG and overall revised of all the years?

Here is some info I found from google as well: The 1980s Mazda RX-7 with the 12A engine gets an average of around 16-18 MPG in mixed city/highway driving, with specific models like the 1984 GSL achieving an estimated 19 MPG city and 29 MPG highway. Some owners report highway mileage closer to 20-24 MPG, but this varies significantly with driving conditions and the car's maintenance.

 

You have to decide if mpg or performance is the priority. The 79 and 80 intakes are much better to use that the FB ones for performance. As to the best nikki to use thats a debatable topic. I'm sure someone will come in with an opinion and some observations about the differences @Jeff20B . I used an 83 intake and the carb that came on it from a JY when I did my hogged out nikki. Works great for me.

 

I mean, I prefer the 79-80 carb for its idle circuit layout. Idle speed is isolated from throttle position, so you don't muck up the transition.

25+ can be achieved with any carb. I have hit 30 with an 85 carb... and an '80 carb, and a '79. It is more about ignition timing and the rest of the car, really, once you have the fuel pressure right.

 

Like peejay, I prefer the 79-80 carburetor. I find them simpler than the later carbs and a bit easier to tune. That's just me. I have rebuilt more S3 carbs that I have S1 or S2 carbs, so maybe my opinion is a bit biased. The S3 carbs and emissions system have more to control backfiring, provide a more stable idle, and they do seem to help the car get better fuel economy. I guess it just depends on what your priorities are for the carb.

 

Thanks guys, I greatly appreciate the great advise from everyone.