I want to know how to adjust the timming on my 86 Z28. The motor is a 305. I was thinking about removing the catlytic converter because it may be clogged but that will probably throw the timming off ( is this correct? ).

Patrick, to check and adjust the timing on your 305 is the same as any conventional motor. The only difference is that instead of having a conventional vacuum advance on the distributor, there is an electronic spark advance instead. You have to disconnect the wire to the distributor, which is right above the AC unit on the passenger side, in the engine compartment. Follow the wires from the distributor and they will lead you right to the connector. After disconnecting the connector, start the engine and check the timing. The correct timing should be 8* BTDC. If it's not on the mark, lossen the distributor and turn it CW or CCW to get it to where you want it to be. Tighten down the distributor and recheck the timing to make sure it didn't move from the mark. Turn off the engine and reconnect the spark advance. You are done.

As far as the cat goes, you will need it to pass smog. If it is clogged up, it will make the engine run crappy and will need to be replaced. It doesn't effect the timing on the motor when a catalytic converter goes bad. You should have it replaced rather then just removing it.

thanks for the reply, that was a HUGE help. I'll probably just get a high flow cat whether its clogged or not.