I have a 1990 RX7 and am having a hard time keeping it timed. I put a new cas in and still the timing moves. Does anybody have any ideas for a rookie at this?

 

The ecu advances timing if your idle speed is up above ~ 1k. Set your warm idle below 1000, preferably to 750.
Generally, setting the timing involves:

1. Stab the CAS
2. Start and warm up the car.
3. Set TPS
4. Adjust idle speed
5. Adjust timing by rotating CAS and using a timing light.

 

http://www.nopistons.com/2nd-generat...-sensor-67074/

 

For TPS (throttle position sensor)
http://www.johnr.com/tps.html

 

my experience is that if you have the A/C and power steering bolted to the bracket they end up getting in the way and disturbing your CAS installation. move them out of the way and it will be easier to drop the CAS in.

 

i set timing the following way.

1. put the engine on the leading timing mark. its the one on the right side of the two marks.
2. remove the CAS cover.
3. remove the little plastic plug on the CAS cover.
4. look in the CAS, there are two wheels in there, one with 28 teeth, and one with two teeth.
5. install CAS so that one of the big teeth is in the middle of the CAS cover hole. this may take a couple of tries.
6 re-install the cover, plug, tighten the CAS, etc.
7. start car, warm it up, jump or ground the "initial set coupler" (green 1 pin on S5, or green 2 pin for S4, by battery)
8. check timing with a timing light. you will be within a degree or two.
9. since the set coupler is jumped, you might as well set the idle speed, which is 750rpm +/-50rpm
9a. if you have an S4 you can set the idle mixture, slowly turn it, there will be a spot where it runs the best, go a teeny bit richer. if you have the emissions installed, and it needs to be all the way rich or lean, there is something wrong.
10. what the hell, set the TPS, i like the factory 2 light method, as its the output from the ECU that matters.

and then you shouldn't need to touch it again for a while

 

^^^exactly what he say,from my experience.