Right i am stumped on this one
Got a bog standard XE in a Nova, fitted engine last week, started and ran, tappets ratling like mad and a bit lumpy but was told been sat for two years so assumed needed running for a while.
Gave it back to the customer, 1 week later wouldnt start, he brought it back and i fitted another earth strap and it ran but like a bag of spanners for about 5 minutes, started seriously backfiring and cutting out.
Then wouldnt re start again.
Inspected the engine (engine was supplied by customer who said was in perfect running order) and found that it had the wrong spark plugs in it...
After taking the rocker cover off to get the plugs out finally swapped them over and fitted Brand new GM plugs for the XE.
Tried to start it but its firing in the wrong place (half way by the sound of it) and then locking up on the bores, changed the crank sensor made no difference.
Take the coil lead off and its turning over at correct speed and sounds fine but when refit the coil lead its locking up again as sparking in wrong place again.
Obviously i have checked the timing, this is spot on, checked the firing order many many times and its correct. Have put earth straps onto any possibly earth point just to try and get it to run.
Have got good fuel pressure etc.
Anyone got any ideas as i am stumped, no matter how silly it sounds please say it as i am willing to try anything as i believe i have tried everything.