I changed the alternator on my 1979 RX-7 over the weekend because the old one basically died on me at a stop sign. Pretty embrassing thing to happen during Friday rush hour. I used to have a nice gurgly backfire with my RX - nothing obnoxious - for the first couple of miles after startup when coasting to a slower speed in 3rd or 4th gear, for example. Well, that backfire has been eliminated with the alternator change. Had to tighten up the belts a little too since they were too loose. I am really happy with the change. The car just seems to run a lot smoother.

 

that is kinda strange, the only reason for that I can think of would be if you are still running a air pump that the belt being tightened was what eliminated it from the extra oxygen getting to your cats...

 

Or the new altinator now has a better cleaner charge providing more constant power to the coils and ignitors ....... wait its a 79 humm maybe never know.

 

Kinda makes sense. If you had a shitty alternator you probably had a really weak spark and it wasn't burning all the fuel. Now with a good alternator the spark is a lot better and it's burning all the fuel, so now there's no extra fuel to go into the exhaust.

 

Same thing happened in my 91. It wasn't backfiring more than usual, but it was running a bit rougher, which I thought was dirty fuel injectors or something. My alt belt started slipping, I tightned it (too much), snapped it, put a new one on and tightened it to proper spec, car runs much much better. I don't know exactly why, but weak spark could have been the issue.

 

for the record, how tight should the alt. belt be?

 

Hmmm, maybe getting the '72 RX2 alternator off my 7 and putting the original back on might cut down on my popping.

 

I like the idea of the car running better, but I sure miss the previous "evil cackle" of my exhaust!