What V8 engine can you put into a 2003 F150 SB auto 2WD that is now running a 4.2 V6. Will a worked up 5.0 be better?

Answer 1

In most cases if you can find a 4.6L v8 or 5.4 v8 from a junk yard truck that is the same year as your truck then you can just swap them over as long as you ALSO take the COMPLETE engine wiring harness. You will also need the computer and one or two other modules as well. Each year is different on what you will need. Do a Yahoo/Google search for something like "2003 F150 forums" and you should be able to read up on what yours specifically needs. It gets even harder if you have the anti theft system, auto transmission, etc. People do it but you need to do your home work.

Answer 2

If you've got the money, the possibilities are far and wide. I know someone who crammed a 6.5 Duramax into a 1st Gen S10... but it wasn't a simple "plug and play" swap.
First, you need to see what the torque rating of your transmission is and make sure it can handle whatever engine you're swapping in. You also need to make sure the transmission is compatible. You also need to sure you can get all the electronics to jive together. Back when TBI was a new thing, the only thing controlled by the ECU was engine-related, so you could swap it out for a carbureted engine if you so wished... not true with today's cars and trucks, and there's a tendency for these vehicles not to be reverse compatible with older engines.