4.8l to 5.3l engine swap now wont start

[ff_jeff]

try this maybe?
Nelson Performance - Security Relearn for no start
from Nelsonperformance.com

[Madd Maxx]

If you have spark and fuel, look for something mechanical. Are you absolutely, positively, beyond a shadow of a doubt sure that you lined up the dots on the timing gears correctly? Since you shaved the heads, did you check the valvetrain geometry? Correct pushrod length, etc? First thing I would do is run a compression check on all cylinders. If the valvetrain geometry is off, you could be holding the valves open.

[ff_jeff]

If you have spark and fuel, look for something mechanical. Are you absolutely, positively, beyond a shadow of a doubt sure that you lined up the dots on the timing gears correctly? Since you shaved the heads, did you check the valvetrain geometry? Correct pushrod length, etc? First thing I would do is run a compression check on all cylinders. If the valvetrain geometry is off, you could be holding the valves open.

thats what quik said in his other thread on this issue. Could be the answer as well.