i wanted to set the timing on my iroc-z, but i have a question. doesnt the ECM determin the timing? because i noticed when i disconnected the timing wire, it was at 4 degrees retard (diagnostic mode?), but once i connect the wires together again, it jumps to 10-12 advanced. now here's my question... wouldn't adjusting the timing manually be pointless if the EMC is just going to set it anyways? is there a way to set the timing permanently? thanks guys

 

The ECM determines how much timing advance you get ABOVE the baseline setting. You have to get the baseline setting right, then the programming in the chip will do the rest for you.

On a TPI the "timing wire disconnect" is a one-wire weatherpack connector sticking out of the main wiring harness over top of the heater box inside the engine compartment. Unplug that, start the engine and check your timing with a timing light. TPIs the stock spec is 6* BEFORE TDC (to the left of the 0 mark while facing the engine standing in the front of the car). Many have found that you can bump it up to ~10* BTDC for a little more performance if you run nothing but premium gas in it.

The difference in the "seat of your pants" between 4* ATDC initial and 6*BTDC initial timing will be quite a lot. Big 'ol blob of torque to be had.

 

that's how it's suspose to work. you set the base timing then plug the EST back in and the ecm takes over from there.

 

well... whats a good place to set the timing if i have a CC502 cam (218 / 224, .495 / .502 112 LSA), ported l98 iron heads and 10:5:1 cr? i'd be running 93 octane all the time... i just dont want any pinging or detonation. then i'll advance the timing whenever i put race fuel in it i guess, lol