Tdc angle.

What is tdc offset angle. And how do i go about trying to get it set right

What's your application? What exactly are you trying to do?

What ECU are you tuning?

Motor is a holden 355 stroker. Setting up full sequential injection and single coil per cylinder with dual knock control and dual o2 monitor. The ecu is a haltech elite 2500

Typically, The method to set this angle is quite simple.

Get a timing light on number 1 cylinder, and use the timing lock feature under "ignition" to lock your timing to something you have marked on the main pulley, say 10 degrees btdc. Run the car, and aim the light at the main pulley. What you see at the pulley should always match what you have set the locked timing to be. If they do NOT match, change the angle offset until they do. Then slowly rev it up with the timing light still on, to around 4-5k. The mark should stay put. if it does not, you may need to either use filtering, adaptive trigger, OR you have wired the sensor wrong (vr sensor is applicable here). If its really jittery back and forth, that is timing scatter, you dont want that.

Here is a video showing how, straight from haltech

https://www.youtube.com/watch?v=2yoxiKJ1KzY&t=351s