I have a strange issue here. 84 S, 12A, Nikki Carb, No emissions. Whenever I press the throttle, there seems to be a spot in the throttle that the car just hesitates really bad. It wouldn't be so bad if it wasn't right were I like to let out the clutch. My theories are: sticking throttle linkage, sticking throttle plates, accelerator pump improperly tuned. What do yinz think of this?

 

Accel pump, or clogged transition circuit, would be my first two guesses.

 

me too, in that order even

 

Bam. It's probably leaning out. Pull the intake plenum off and have someone blip the throttle (or pull it yourself from the engine bay). You should see two streams of gas, one from either side of the accel pump nozzle. There's a pic of the nozzle here, third pic down: https://www.rx7club.com/1st-generation-specific-1979-1985-18/how-test-nikki-fuel-jets-without-rx-7-a-964299/

 

The accelerator pump linkage has worn out on almost every carb I rebuild. My guess is that this is your problem. The hole in the lever on the throttle shaft (where the AP arm connects to) gets worn larger than it should be. Also the arm itself gets worn thin. So there is a lot of play when you first open the throttle, resulting in the AP not squirting fuel straight away.



I repair the hole with metal work solder and re-drill it. Also have to solder the arm if its worn through.

 

Thanks, I will try tuning the accel pump, then cleaning the carb AGAIN! This thing has been dipped for days scrubbed all over and blown out with air/ carb cleaner. I would like to think nothing is clogged but maybe. I'll check out the linkage too.

 

I have the same issue with my latest build, Justinfox. When you free up all the junk that's been building in these carbs the past 25 years, it's really hard to clear it all out. I spent hours soaking and cleaning mine only to have one primary jet clogged when I finally reinstalled it.

My accel pump needs tuning too... it leans out during transition and sputters.

 

If you rebuilt it recently, make sure the accel pump circuit ***** and weights are in the right holes, and in the right order. One of the half-dozen most common errors during a carb rebuild is to end up with the ball on top the weight - - or to neglect to put the ball or weight in, because you never saw it fall out during disassembly.

Both errors result in a weak accel shot.

 

It seems to be fuel delivery related. Every time i clean my filter and blow carb cleaner into the rails it seems to go away for a bit. My clear filter up by the carb is always getting full of dirt and slowing down the flow.

 

Sounds like you need to drop the tank and re-line it

 

I never concluded this thread. It ended up being a small hole in the accel pump diaphragm. I noticed it was getting worse and worse, the hole must have been getting bigger. It was the only thing I didn't replace during the rebuild b/c the one that came with the kit would always get stuck to one side. I put it in anyways and after a bit, it got broken in, and stopped getting stuck.

 

Ding ding ding ding... we have a winner! Grats!