3.8 in place of 4.2 swap

[CIRCLEBFAB]

Just finished putting a 3.8 out of a 99 mustang into my 97 f-150 that had a 4.2 automatic trans with 245,000 miles and wanted to tell everybody how easy this swap is. There was only 5 parts I had to swap off the old 4.2 to the 3.8 and that was the intake manifold, water pump,cam position sensor,oil pressure sensor and the knock sensor. All my accessories,power steering pump,air conditioner compressor,and alternator all bolted right up.

I purchased my motor out of a 99 mustang with 3.8 automatic trans and 49,000 miles for $400.00 at a local wrecking yard. Be sure you get the flywheel with the engine because it is differant than the 4.2 flywheel and must be used, it will bolt right up to your convertor and trans. The harmonic balancer on the 3.8 is 1/2 inch bigger than the old 4.2 but was not a problem I still used the old 4.2 belt with no problems. The water pumps are the same except the fan bolted on a little differant than the old one.

Also no need to pull the air conditioner condensor,just pull the radiator and you will have room to make the swap. I placed a piece of 1/4 inch plywood in front of the air condensor in case I accidently hit it. Have put a couple hundred miles since swap and everything is going great!

[monckywrench]

Plenty of otherwise good F150s go to scrap because of dead 4.2s.

What did you run into with the engine wiring harness? Do the injector connections match?

[CIRCLEBFAB]

Originally Posted by monckywrench

Plenty of otherwise good F150s go to scrap because of dead 4.2s.

What did you run into with the engine wiring harness? Do the injector connections match?

I am sure you could just use your 4.2 injectors with no problems however mine were junk so I used the ones that came with the 3.8. Yes I had to swap the connectors (cut and splice)to the ones that were on the 3.8

[monckywrench]

Thanks!
I try to keep track of which injectors come with which engine. Wiring is no sweat, but if I need a single injector I can hunt one easier.

[89ragtopgt]

hi i have a motor from a 1994 mustang will this replace the 4.2 in my 1997?

[monckywrench]

"hi i have a motor from a 1994 mustang will this replace the 4.2 in my 1997?"

Here's how to tell:
Remove dead 1997 engine without damaging any sensors. Set it next to your 'Stang engine, then play sensor, bracket, and manifold matchup. Be careful removing injectors etc. Your 'Stang block may or may not be drilled for all the sensors so inspect carefully.
Digital cameras help a lot. I take pics of everything especially harness routing.

[89ragtopgt]

Originally Posted by monckywrench

"hi i have a motor from a 1994 mustang will this replace the 4.2 in my 1997?"

Here's how to tell:
Remove dead 1997 engine without damaging any sensors. Set it next to your 'Stang engine, then play sensor, bracket, and manifold matchup. Be careful removing injectors etc. Your 'Stang block may or may not be drilled for all the sensors so inspect carefully.
Digital cameras help a lot. I take pics of everything especially harness routing.

OK will the intake swap over? so the bell housing will bolt up? then i just need to get a flexplate for an auto for the 3.8l as this mustang is a standard and the truck is auto. do these 4.2L units have a knock sensor in the block? will the front acc brackets from the 4.2 work on the 3.8?
thanks again

[monckywrench]

"hi i have a motor from a 1994 mustang will this replace the 4.2 in my 1997?"

Here's how to tell:
Remove (assuming it's dead) 1997 engine without damaging any sensors. Set it next to your 'Stang engine, then do sensor, bracket, and manifold comparison.

Be careful removing injectors (pull out as straight as possible to avoid knocking off the plastic caps on the tips) etc. Your 'Stang block may or may not be drilled for all the sensors so inspect carefully.
Digital cameras help a lot. I take pics of everything especially harness routing.