OK i can get one of 2 engines locally to me
a 2004 with 170k miles with secondary air
a 2004 with 80k and no secondary air

Mine is a 2003 with secondary air so can I use the one with out??

Thanks
Keith

 

I'm not sure I would replace my motor with any 03-04 block...if you want a 4.6 I would either go with a P38 4.6 block or swap 4.6 internals into a 99 or 00 4.0 block. I think you need to keep SAI if I'm not mistaken.

 

What is the power difference on the 4.6 to 4.0 as they have a 2001 engine with secondary air. And is there going to be any other things that will not fit if I go as a down grade in engine size

 

the one at 80k they want a 1000.00 the one with 170k 400.00 the 2001 no clue on condition and they asking 200.00

 

Everything should fit just fine. Will need a 4.0 ecu. Both of mine have 4.0s so I can't speak to the power difference. Feels like a great opportunity to grab the 2001 and strip it down and move over your 4.6 internals and refresh/new seals/gasket everything and a bigger cam. That's what I'd do if I was in your shoes, best chance to have a leak/trouble free motor with maybe a little power bump.

 

Get the 01 engine.
Swap your 4.6 crank into it and toss a new cam in it.
Re-seal everything.
Put the SAI heads back on and run it.

 

Not quite a direct comparison, as my 4.6 is a GEMS in a P38 and my 4.0 is in my D2. The 4.6 has considerably more power. Where I live in British Columbia, we have the steepest/longest highways in the country. The 4.6 is adequate, you can maintain above the 120 kmh speed limit up the steepest hills. The 4.0 is more like 105. It's really about the only disappointing thing about my D2 (other than the poor departure angle).
I have a spare, supposedly good 4.6 GEMS in my shed, that "someday" I want to put in the D2, but it's more work than a direct swap, as it's GEMS, and the D2 needs Bosch.

 

You can just swap the 4.6 crank over. thats the main difference.

You can use the GEMS block, but the crank sensor will be different.
Other than that the blocks are the same, heads should be unless SAI.

 

Logan your saying I can just move the crank over or do I need the rods and pistons from the 4.6

 

unfortunately I need to minimize down time and labor cost as I can't do the swap myself