Curbside Tech – Wrapping up My Mustang II Engine Swap

During an engine swap, sometimes your plan takes a detour…

 

This week, I’m going to review the two major issues I encountered while installing the fuel injected Scorpio engine into my Mustang II, but before that, let’s cover the (mostly straightforward) modifications I made to the charging and starting system.

The engine block matches up- The accessory drive not so much…

 

I had hoped to use the Scorpio alternator mounting brackets in the Mustang, since I wanted to keep all the Scorpio accessories, including the power steering pump. The Soul Survivor had been equipped with power steering when new, but a previous owner installed a manual rack. I wanted to restore the power steering, but to do so I needed hydraulic pressure.

Alternator mounted to the 2.9 V-6 using the Ranger brackets.

 

However, this was not to be. The passenger side frame rail interfered with the alternator when mounted to the Scorpio bracket. The fix was pretty straightforward-  I found a bracket and alternator off a 2.9 V-6 which moved the alternator up. The “new” alternator also included an internal regulator, so I bypassed the fender well mounted regulator.

Nothing very complicated- The factory solenoid becomes a control device for the new starter.

 

The 2.9 engine also included a starter mounted solenoid, instead of Ford’s system using a remote mounted solenoid. Rather than rewiring the existing starting system, I ran battery power directly to the starter solenoid, and then connected the starter’s control terminal to the remote solenoid.

Braille battery- Note the clearance between the battery and the exhaust manifold.

 

Finally, I used a Braille battery in to replace the Mustang’s Group 26-R battery. Due to the tight confines of the engine compartment, the factory battery sat right on top of the exhaust manifold. The smaller Braille battery still handled the starting duties, but allowed air space between the battery and exhaust manifold, and also allowed better access to the back cylinders on the passenger side.

The 2.8 manifolds (top) had 2 common ports and a different bolt pattern .

 

Speaking of exhaust manifolds, the exhaust system for this exchange ended up being the most expensive part of the project. As I wrapped up the project, I wanted to drive the Soul Survivor to the Mustang’s 50th anniversary celebration in Las Vegas. As often happens, I was under a considerable time crunch and could not use the original manifolds on the 2.9, since Ford modified the exhaust outlet spacing on the newer motor.

As you can see, the steering U-Joint has a smaller diameter than the factory joint.

 

On the right side, the Scorpio manifold almost cleared the frame rail, and I only had to grind a little material off the manifold flange. On the left side, the Scorpio manifold interfered with the steering column. To address this, I acquired a manifold out of a Ranger pickup. The manifold cleared the steering column, but the isolator (rag joint) rubbed against it. A smaller universal joint for an aftermarket Mustang II rack solved that clearance problem.

Whoops- There goes my budget! When dealing with fabrication projects, never tell a shop you’re working on a critical deadline

 

With the exhaust manifolds in place, I took it to a muffler shop for a custom exhaust system. I should have shopped the job around, and I made the additional mistake of mentioning my time crunch. All told, the exhaust ended up costing me more than the donor car (to be fair, I did get that car for a song…)

An example image showing the difference between Front and Rear sumps

 

The last system I’ll cover is the oiling system. It was a major pain, mostly because the Scorpio engine used a rear sump while the Mustang II came with a front sump.

Same basic block, two different cam drives….

 

In addition, the 2.9 engine used a roller chain camshaft with hydraulic lifters, instead of the gear driven solid lifter cam in the 2.8. You wouldn’t think the camshaft drive would affect the oil pump but life is a learning experience…

During the swap, we pulled the 2.8 engine and stripped off the parts we planned to re-use. This included the oil pickup tube and oil pan, but not the oil pump.

Similar but different. The 2.8 pump has the smaller intake port.

 

However, when I tried to mount the pick up tube to the 2.9 pump, I discovered the pump inlet did not match the tube. As this picture shows, the 2.9 pump inlet uses a three bolt flange with a larger inlet (compare it to the 2.8 pump with it’s smaller inlet and two bolt flange design). Also, the 2.9 pump was slightly taller and interfered with the Mustang oil pan.

More differences- The 2.8 shaft is on top, 2.9 shaft below.

 

Engine swaps are not for the faint of heart- The 2.8 pump bolted up to the 2.9 block so I swapped over to the old style pump and discovered the 2.8 pump used a hex driveshaft while the 2.9 used splines. Therefore, the Scorpio distributor could not drive the Mustang oil pump.

They sure LOOK the same…

 

To solve this problem, I sourced a Ford TFI distributor out of an early eighties 2.8 Ranger pickup. The distributor control module matched up to the the Scorpio wire harness, and the distributor drive mated to the hex shaft. The housing was identical to the 2.9 housing, so I expected it to drop right into the block, but after twenty minutes of effort, it appeared I was wrong.

 

Over the span of time, I’ve learned to walk away when things don’t come together. The problem is typically some factor I’d neglected to consider, and until I identify that element, further effort will not generate any positive results.

Mentally chewing on the problem during my drive home, I suddenly realized root cause lay in the updated camshaft drive. You see, a gear drive spins the camshaft in the opposite direction of a chain drive, and as I showed you, Ford changed the camshaft drive for the 2.9.

Eureka!

 

Sure enough, comparing the 2.8 and 2.9 distributors, the drive gear tooth angle did not match up. I swapped the 2.9 gear onto the 2.8 distributor, and it dropped right into the engine.

Sigh…

 

Once I bolted everything up the car fired up and drove quite nicely EXCEPT… During sustained operation above 2,000 RPM, the valve train stated clattering like a Model T. It seems the hydraulic lifters in the 2.9 required more oil flow than the 2.8 pump could provide. The pressure gauge showed OK pressure, so I drove up to the Mustang 50th Anniversary celebration with my fingers crossed.

Sorry- No pictures. I may have been a bit aggravated at this point ;-), and did not break out the camera.

 

The engine survived the trip without damage, but once I got back home pulled the motor, modified the oil pan for pump clearance, and fabricate an oil pickup tube.

That wraps up the engine swap on the Soul Survivor. As I noted earlier, despite these issues I’m very satisfied with the final product. Next week, we’ll take a look at adding cruise control to a car without this option.