hello all,

I was looking over my rx-7 and seeing how the throttle plates are almost closed, if not closed, when I release the fast idle cam roller manually. This would be idle for the car. Im wondering where the car gets its air from, is it like 100% from the BAC, or like 90%,etc.

I also see a tiny hole in the middle of primary throttle plates, or is this the only feed for the idle?

My books say the settings for the primary throttle plates to wall clearance are like almost nothing , .016 inch

I find it hard to picture that feeds the entire idle..

anyone know the finer details?

 

Some comes through the slightly open primary throttle and some comes through the BAC valve.

The hole you see between the secondary plates in the TB is for the oil nozzle and fuel injector air bleeds. Since this air is being sucked into the engine, it also contributes to the idle air quantity.

Remember the idle airflow is a tiny fraction of the full load, full revs airflow, so that 0.016" gap (plus the other air sources) is enough.