Adjustment screw on 13b na
 

What's the brass screw on the top of my throttle body do? Its a 1988 13B n/a and where abouts should it be as far as turns from seated? I am mechanically inclined but have no experience with rotors. Is it a fuel screw like on a dirt bike/ four wheeler Carb? And if so do you adjust it like one? Thanks

It's the idle adjust screw.

In general you should not mess with it unless you are following the factory idle set procedure. And if the idle is messed up in some way, then you must correct that initial issue before trying to set the idle.

The Factory Service Manuals for all years of RX-7 (and many other rotary cars) can be downloaded for free here: http://foxed.ca/foxed/index.php?page=rx7manual . They contain all common service information information and more, and are an essential tool for any sort of service work that needs to be performed on these cars.

Additionally, the Haynes service manual for the 1986 thru 1991 RX-7 (both turbo and NA) can be found at most local auto parts stores or purchased from any good bookstore (ISBN number 1 56392 007 7). It is only about $25 and is a great quick reference for things like this. Not only does it contain most of the information in the FSM condensed into an easy to read format, but it includes full wiring diagrams as well.

These manuals will answer 99% of service related questions for the car and if you intend to do your own repair work, you will need at least one of them. Preferably both, since the FSM is a free download. The Haynes is a good quick reference covering 99% of questions, while the FSMs show complete and detailed procedures.

So where is this "Initial set coupler" that FSM says to connect a jumper too?? Or where is "variable resistor" that i need to check resistance on and what do they do? This is why I posted this question because the service manual is as clear as mud to me. I thought that was the idle screw so I played with it to turn my idle up (before i realized that the TPS needs adjusting and need to do that once I pick up a multimeter. Now it mis-fires on idle.

I forget where it is offhand, but it most certainly is in the FSM. From memory, it's near the leading coil.

It's in the FSM. You'll find it on the passenger shock tower. It's roundish, marked "L" and "R" or "Lean" and "Rich". The variable resistor adjusts idle air/fuel ratio. However you shouldn't touch it unless it has been messed with. To use it, the initial set coupler must be set and the idle speed should be as close to factory as possible.

Sounds like you leaned it out too much.

If all the adjustments have been messed with, then setting them up from scratch is time consuming as it basically involves going around and around adjusting one thing after another, very slightly, slowly working towards an idle.

Well i played with those and got it running and idling great. I understand tuning but didnt know the adjustments. And sorry about not knowing that stuff, I read about them in the service manual but it just said "Adjust this" but never explained where they were and what they did. Thanks Aaron for the help and sorry if I sounded retarded...