Tech Tips

401 Engine Swap Must Do's

Replacing a '87 360 with a '78 401

There are a few details that need to be known when doing this type of swap. Especially if you are like me and putting a mid-to-late '70s engine into a late model Wagoneer.

For the most part, it is a very easy engine swap. The 401 is the same block size as the 360, so the bolt pattern and most parts are exactly the same. I was able to transfer all major items (carb, manifold, pumps, etc.) over with no problem.

But there are a few items which hung me up in the swap that I thought everyone should know about.

1. Know what the engine came from

In other words, get the year, and what type of transmission it was hooked into. In my case, the 401 was a '78 hooked to a TH400 tranny. This is vital in determining steps #2 and #3.

2. Flexplate

If you plan to get the engine balanced, the flexplate has to be correct. My 401's flexplate would not have hooked into my 727 tranny because it was originally going into a TH400, so I needed to put on the flexplate for the 727 tranny, before balancing. A safe method would be to get the flexplate for a 74 Matador with 401 and 727 transmission (to ensure flexplate fits the 727 and is balanced for the 401)

3. Adapter Ring

This was one of the discoveries I made by chance when putting in the 401. Since the engine was originally hooked to a TH400, the crank had a small adapter ring for the snout of the torque converter. It is a thin steel ring, that is pressed into the crank. Of course, the snout on the torque converter for the 727 was too large to fit within this ring. Make sure this ring is out before mounting the engine. Otherwise you will end up like myself, dropping the tranny, and chiseling out the ring with little space to maneuver.

4. Starter

If you have the later model Mitsubishi starter (typically on 1988-1991 Grand Wagoneers), you will have to convert to the older Ford starter (Try Autolite P/N A3209 at PartsAmerica online) with fender solenoid (try Borg WarnerP/N S113 at PartsAmerica online). These part numbers are from PartsAmerica online as of Sep 2007 as found on a 1980 Cherokee with auto trans, or you can look up parts for 1985 Grand Wagoneer.

5. Other recommendations

  • Make sure to prime the engine before you start it for the first time (don't ask)
  • Replace the Motor Mounts
  • Depending on what modifications you make to the engine, you may need to re-jet your carb.

That's really about it. Just be sure to check on these items before installing the new engine, and your swap will go buy very smoothly.

Toby DeMoss