Iv been working on a Subaru that my friend started and couldn't get running so he called me he replaced a burnt valve in the head and re installed it got it back together and no start. i got there found that the timing belt was all wrong re installed using the correct timing marks not the arrows. and no start still. compression checked to make sure there was no additional valve damage do to being out of time. compression was between 145-150psi checked ignition timing it is firing about 180 out and there are no dtc. any input im out of ideas

The info in previous answers is correct about making sure the cam marks are in correct place and engine cylinder #1 is at top dead center. Other thing you have to watch carefully is where the timing marks end up when belt tensioner is fully engaged. On MANY engines the marks will move slightly when belt is pulled fully tight. You sometimes have to start with the belt looking one tooth "off" to have it lined up when belt fully tight. Have seen this on many cars that when assembled loose all is lined up - but if you check when belt fully tight things are just a little off.

The only thing I can think of is the timing gear where the timing sensor or crank sensor is, is backwards. Are you sure it's right? Did you change the gears or are they original to that motor (Some years have different timing marks for the sensors, I found out hard way)? I know that these are very hard to line up right so I understand. I wish I had a picture to show you but I don't.

If its firing 180 out you need to make sure when you set the timing its on the compression . when the piston is at the very top of the stroke The first one is the Intake stroke, the piston moves down the cylinder while the intake valve is open. Once the piston reaches the bottom of the intake stroke the intake valve closes. The next stroke is the Compression stroke, during this stroke all valves are closed and the piston moves back to the top of the cylinder compressing the air fuel mixture. Once the piston reaches the top you are starting the ignition stroke. With the piston at the top the spark plug fires igniting the compressed air fuel mixture forcing the piston back to the bottom of the cylinder. Once it reaches the bottom you begin the Exhaust stroke. The exhaust valves opens allowing the piston to rotate back to the top pushing out the burnt gases.