A really good thread and worth to bump it up I believe.
Also anyone could help with my issue.
i changed head gasket and machined and put all the bits back,,
so excited last night before put the key back.
But engine doest not fire. Keep cranking seems no spark.
can smell a bit petrol from exhause, but not burning at all.
could not think anything wrong and dont know where to start.
Anyone could help, thanks heaps!!

Model car? EA/EB/ED/EF/EL/AU?

If it's EA/EB/ED/EL then it might be your TFI module or coil that have died. If EF/AU then maybe coil pack. This is with the assumption you don't have spark. Might want to check that.

It can also be Smartlock if your car has it, but I can't remember what Smartlock disables, but if you have it, does the Smartlock light flash on your dash? If so, you'll need to reprogram the key into the system by leaving the key in the ignition in the on position for an hour. See if that works.

Another option could be a relay/fuse, main engine relay/fuse? I'm hazarding a guess here.

Thanks for your reply. It is an El xr6. Yes no spark, checked coil it should be good. I connect another coil and tested. Smart lock ok checked according to book. Tfi module difficult to test i have to pull apart inlet again, pain in xxx. Will do it. Appeciate your help

May be a dumb suggestion but being an EL, did you re-fit the crank angle sensor correctly?

EDIT... Never mind...