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[font size="1" color="#FF0000"]LAST EDITED ON 05-Apr-01 AT 10:35 PM (EST)[/font][p]I was told that a 4.2 is a slighty stroked 3.8
so I would guess any thing would exchange except
the rods and crank p.s. My Dad has a 2000 ford
f150 with a 4.2 v6 5speed I have a 1982 f100
with a 3.8 v6 3 speed the 4.2 just has 10,000
miles my 3.8 has at least 150,000 and we love
our v6s :7
The heads, intake manifolds, intake runners and fuel rails are different on the 4.2 vs the 3.8 motor. The block is the same but the stroke is longer on the 4.2.
I have heard of some Mustang owners putting 4.2's in their late model (1994-2000) mustangs, using the 3.8 oil pan and a custom hood. (The intakes runners are MUCH taller on the 4.2). Never tried it myself however. Check out http://www.v6power.com
To sum it up, they are in the same family of engines, but there are quite a few differences.
The 3.8L and the 4.2L are both 90 degree V blocks with the same deck height and bore spacing. This means that even though the heads and intake manifolds are different they will interchange. The following info is a copy from a previous post I responded to that might be of some interest.
Don't know if anyone is still watching this string but there is something all 4.2L V6 owners should now. The 4.2L is a bored and stroked brother to the 3.8L found in Windstars, Mustangs and the old Thunderbird Supercoupe. I have researched this because I was trying to make a 4.2L supercharged engine out of 3.8L parts and stick it in a Mustang.
This project never evolved for me but I discovered that the cam, upper intake, supercharger and heads from a 3.8L Supercoupe engine will fit on a 4.2L engine. Most of these parts are still available over the dealer's parts counter but I would find a total Supercoupe T-Bird if possible. I never researched this swap for a F-150 but the first real issues you will come across is getting the FEAD system to operate correctly. The FEAD system on the 4.2L must extend about 7 inches forward of the engine block and the 3.8L Supercoupe's FEAD is very tight and close to the block so this will be an issues to over come. FEAD = Front End Accessory Drive