Hello, I have a 1988 F-150 standard cab with the 300 and 5 speed trans, the motor is bad. Yes yes I know I will draw a lot of comments about the motor probably not being bad, but it is seized and then some. Long story. By the previous owner. Bought it because the frame and body is nice.

I have a 2003 F-150 with the 4.2L V6 automatic trans I have owned since new and maintained the crap out of the engine and trans, drove all over the country, and has low miles (early 100,000 range), and have never needed to do anything close to a major repair. Since it is low miles and maintained by me since new and runs like a top, I would like to use it as somebody hit the truck in 2021 and bent the frame and it has been parked in storage since. However it seriously was the best engine and trans I ever had and I would take that 4.2L across country tomorrow and likely make it, the 300 I would not (sorry 300 lovers), and I just want that "set it and forget it" newness reliability I enjoyed with my 2003 over my 1988. I have had my share of 300s and yes they are amazing engines but always felt like I was adjusting something.

You could argue I should keep the 300 and I would consider it but it is already blown and gone so that is out of the equation and not what I want to do anyways.

Anybody have any guidance on the swap?

Also would I have to swap the auto trans or could I stay with the manual?

 

Also I appreciate any other input about different engine combinations, like I usually see in these types of threads, but the reality is is that I have both engines here and paid off, and not looking to source another engine. So this is the combo. Even if it doesn't make a whole lot of sense to some, it's sure a lot better than having two dead trucks laying around!

Thanks!

 

Sounds like a plan and you already have a donor vehicle to make it easy....er.

I've done a lot of engine swaps and as long as you have a donor to steal everything from, it's not too bad. The hardest part may be fabricating engine mounts. I will say that the best thing you can do beforehand is get the actual Ford wiring manual for each vehicle first and study/make notes of wires that need to be spliced to mate the 1988's cab harness with the newer underhood harness. Keep all of the engine wiring intact and pare down the vehicle side of the 42 pin connector from the 2003. You will find that a lot of the wiring will be the same color for the gauges/engine sending units.
Finding a safe method of mating the fuel lines (pressure and return) may also present a challenge as they are not in the same spots.

 

Neat sounding swap.

Engine mounts shouldn’t be a big deal. There was an older version of the 3.8 v6 that sat in the early 80s trucks.

The 4.2 uses the same 90* bolt pattern as the 300 and Windsors, so that’s good.

Find a manual transmission 4.2 computer and start lining things up from there. I’m sure an ‘88 model is missing ways to get inputs to an electronically controlled transmission, so you have to simplify this as much as possible. You’ll have to figure out oxygen sensors. You’ll be going from one to four. Maybe enlist a tuning guru to get rid of what you can.