Member of the Family (Part 2): Installing Our Ford 408 Windsor in a ’68 Mustang

(Image/Christopher Campbell)

We were a little sad to pull the original 289 from our project, but after 250,000 miles, it’s completely worn out, showing low compression on all cylinders and leaking oil.

A 351W-based swap is by far the closest thing to a dead drop-in you can get with an original 289/302-powered FoMoCo project. It’s essentially the same block, just with a raised deck height, so it will drop right onto the original motor mounts. It’s really the little stuff that will get you, especially if you changed a lot of stuff like we did. This is our 408 just as we left it from Part 1 of this project.

While it may be taller and wider, reaching the top bolts on the bellhousing with a 351W swap is no worse than with a 289 or 302. It’s on the sides and top where things get a bit tight.

Many assume that standard 289/302 headers will fit, but that’s rarely the case. While they will bolt up to the heads, the raised deck height pushes the heads upward and outward, usually killing clearance—particularly on the driver’s side. Fitment gets even more critical if you opted for a Borgeson steering box swap like we did with our RideTech suspension upgrade. These 1-3/4″ stainless steel ceramic-coated headers from JBA (PN: 6613SJS) are the only long tubes on the market specifically designed for a 351W swap that’s using a Borgeson power steering conversion.

From underneath, you can see that there are miles of room on the passenger side, as usual, but the driver’s side is snug even with the right header. You can also note that we went with Energy Suspension black poly motor mounts vs. stock rubber.

For visual reference, here’s our 14:1 Borgeson power steering conversion box for 1967-1970 Ford Mustangs with 1-1/8” sector shaft (PN: 800111) prior to the engine install. While it is a compact box and a direct bolt-in, it’s how the dimensions change vs. the stock box that can become an issue.

The Borgeson box does not stick out as far toward the engine, but it is taller, so the tubes have to account for that. Looking upward from underneath, even with our JBA tubes bent for exactly this application, it’s a snug fit. This is what everyone online is frustrated about who are conducting searches for a “351W swap” or “Borgeson box swap.”

Space isn’t nearly as cramped on the passenger side since there isn’t any steering to route around, but we opted for a Summit Racing high-torque gear reduction starter since its small size keeps it as far as possible from hot header tubes. The clockable mounting plate also makes it ideal for positioning the wires and routing the wires.

Like most mini starters, the Summit Racing one has a built-in GM-style solenoid. A simple rearrangement of the wiring will get it working with the stock FoMoCo style solenoid.

Bigger engines need more cooling, especially if you’re thinking about street cruising with the A/C on during summer, so we opted for a tested and vetted Exact Fit combo from Griffin (PN: CU-70039). The dual Spal fans will raise demand on the electrical system, which is why we upgraded the alternator in the previous installment, but they will also cool more consistently at low rpm and speed and reduce drag on the engine. The kit comes with the necessary wiring and relays, but you will need to add a controller with temperature probe such as Dakota Digital’s Programmable Dual Fan Controllers (PN: PAC-2750).

Another place where a clockable housing really comes in handy is the mechanical fuel pump. This Edelbrock pump (PN: EDL-1725) flows 110 gph, and we can place the outlets anywhere we need them. Plus, the polished housing looks great.

Ignition is what drives an engine, so we always prefer to go strong here. Rather than a traditional canister coil, we went for the more aggressive E-core Blaster HVC (PN: 8252) which is better suited to the Digital 6 AL box (PN: 6425). We also placed it on the inner fender away from the engine to reduce heat soak.

Distributing the spark is our vacuum advance MSD distributor (PN: 8354) and a universal set of MSD Super Conductor plug wires that we cut to fit (PN: 31183). If you’re like us and require neatly routed wires, we highly recommend the MSD wire separators as well. Summit Racing also carries pre-cut sets for Windsor engines. We’ll need to get it on a chassis dyno to really dial it in, but we started with 14-degree initial timing and 34 degrees of total timing.

Here’s the correct set-up for our MSD Ready-to-Run distributor paired with a 6AL Digital ignition box. Also worth noting, contrary to some posts we’ve seen online, the 12v feed in the stock engine harness is an acceptable place to pick up 12v ignition.

Purists may cringe at the sight of a Saginaw power steering pump on a Ford engine, but the reality is that with the swap, the stock pump just isn’t up to the demands of the Borgeson box. We initially had a different style pump on the 408 in the first installment, but swapped to this pump on Borgeson’s advice. Note the large spacers on the bracket; these will be removed once we install our A/C compressor bracket down the road.

For fuel delivery, we opted for a sleek and stylish Road Demon carb with vacuum secondaries for improved street cruising mpg (DEM-RDA-650-VS). Holley has completely re-engineered and re-calibrated these carbs for better drivability and full throttle performance, and the fuel bowls now have dual threaded inlets on each side, dual sight glass windows, and internal baffling for improved fuel slosh control. That’s a must have if you’re planning to do any autocross work down the road. The Demon needed no adjustment out of the box to run well, but we’ll dial it in on a dyno down the road.

We know some of you have been eyeing that Edelbrock Performer RPM Air-Gap intake and doing mental math with the 351W deck height to see if it will clear the stock ’68 hood. The good news is: Yes, it will, provided you have a deep enough drop-base air cleaner. To allow for a 3-inch tall element for sufficient airflow, we went with an Allstar 1.75-inch drop base (PN: AAF-ALL26092). We topped it off with a stock 289 Hi-Po style lid which looks appropriate, and is nice and flat.

It looks good, nice and simple like that, but sharp eyes surely noted the three-groove crank pulley. We’ll be upgrading and reinstalling the A/C down the line. The good news is that now it’s a runner!

Here’s the actual break-in dyno run for our 408. While it’s a low revver with peak horsepower coming in at 5,000 rpm, that super-flat torque curve is gonna feel great on the street. Could it make another 100 hp with more aggressive heads and another 1,000 rpm? Sure. Probably more. But that’s not what we were after. That long, flat table top of a torque curve that sits well above 400 pound-feet from 2,750 to redline is what we were after.