hey guys, i have 2 questions. First of all i have a 1980 rx7 that i am rebuilding. It idles and runs great, but during acceleration the car pauses for a second at 4500 rpms. I have no clue what could be happening or if it is anything i need to worry about. Also, i have heard that a vacuum leak or bad shutter valve can cause backfiring, which my car does. how do you check for a vacuum leak and or how do you change the shutter valve. Thanks alot.

 

The early models which are the SA ones 79-80 do not have a shutter valve on them. They have a completly different system and are prone to heavy backfiring on deacceleartion.
The easiest part to check is the dashpot which is attached to the carb near the firewall.
Exhaust leaks on the Sa will also cause this problem.
For vacuum leaks just take some carb spray and shoot down the intake and carb area.