Can anyone tell me if a Nikki carb from a 1984/5 car is the same as a 1979, what year did Mazda change the 12a engine?
Basically i want to change the carb on my '79 rx and they were only available in the Uk from '84 so finding a carb for a '79 would be pretty hard.
Would the Edelbrock 500 be any use as a replacement and if so what mods are needed to fit it?

 

There are a large number of alternate builds of the Nikki; even within a single model year there have been several different buildouts.

Example; 1980 model year saw 6 distinct builds; California, Federal, and Canadian Manual Trans builds, and California, Federal, and Canadian Auto Trans builds. The differences included different jetting, different vacuum porting, and the inclusion on the Cali models of a richer system. Those are north-american builds - - I don't know if the Euro builds were different or not.

Year-to-year, the variations were even greater, most but not all revolving around emissions equipment. At some point, I know the size of the barrels changed sigificantly, too.

This doesn't mean that you can't make a later-model carb work on an earlier engine, but you'll have more work to do to get it right.

 

The venturis didn't change from 79-85.

 

Primary barrells appear to be smaller in the 81-85 cars but flow just the same. The 79-80 Carbs are designed to run richer due to the thermal reactor system instead of a catalytic converter as the later year cars had

 

I've never had an FB; I know that the openings on top LOOK smaller to me, is all.

 

they are. the 81-85 style flows better