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Hidden Modifications

Hidden Modifications

Text and photography by Miles Cook

Suppose that you have a classic Falcon, Fairlane, Galaxie, Mustang or any other collectible Ford or Mercury of any year or body style. We’ll imagine that it’s all restored or in fairly good shape as is. Or if the car is a project that’s in the process of going together, we’ll shoot for the goal of having it on the road in the next six months to a year.

Let’s surmise that you want the car to look essentially stock, but you’d like it to drive better than the typical above-noted car that’s 100 percent original. We’re not talking a 10-second drag car or an extreme open-track road racer, but rather a good-performing street car that can keep up with just about anything on the highway and hold its own on the twisty stuff, too.

If these parameters are what you’re thinking of, then this overview will be right up your alley. In simple terms, we’re going to focus on the best upgrades you can do to a vintage Ford that most people will never know are there–unless you mention them of course.
Note that the first section will encompass things that can be done with engines that are nearly or totally invisible, while the remaining sections will focus on other areas of the car.

This ’69 Mustang is a great example of what this overview covers. At first glance what can you see that isn’t stock on this car? Not much really, other than a set of Baer disc brakes, larger Vintage Wheel Works 17-inch wheels and a Maier Racing fiberglass hood. It’s a great way to build a fun-to-drive Mustang or other classic Ford--keep it subtle but have plenty of hidden but effective upgrades that dramatically improve the overall driving experience.

The 351W in our ’69 looks fairly stock with the only really noticeable external upgrades being its JBA headers, Edelbrock Performer 351 intake and late-model-style distributor cap. It even has the stock “Power by Ford” valve covers. And if we painted the intake manifold, aluminum cylinder heads and valve covers engine-color Ford blue, they’d be even better concealed. Our goal here was to make the engine look like a fairly ho-hum 351W as found in other ’69 Mustangs. While it looks the part, this Windsor is actually a reasonably healthy street engine that has plenty of internal upgrades. All them invisible, no less, to make it much stronger than a stock 351W. Included in the Smeding Performance short-block are a freshened crank and stock 351W rods. Forged aluminum flat-top pistons net about a 10.4:1 compression ratio. With a 0.030-inch overbore and a stock stroke, the 358-cube Windsor is topped with a pair of AFR 185 aluminum cylinder heads which are home to a set of Comp Cams roller rockers. A Comp XR282RF hydraulic roller cam gives the engine a decidedly lively personality. With the Edelbrock intake, a Holley 650 cfm carb, a set of JBA headers and a Pertronix Ignitor ignition, this combo makes more than 300 horsepower at the rear wheels without really looking the part.

As you likely might be well aware, several things can be done to an engine that will, for the most part, remain totally invisible to the casual observer. Even with a closer look many would be hard-pressed to notice much of what we touch on here. In fact anything inside an engine will never be seen or known about by anyone, unless you happen to discuss it.

Stroker Short-Block
This one is pretty obvious. On the outside, a 347 will always look like a 289 or a 302 and a 392, 408 or 427 will always look like a 351W. Is this the ultimate hidden mod? Could be. Take, for example, this ’70 Boss 302 Mustang engine. A show-quality restoration effort, could anyone detect this to be a 345-cubic-inch stroker motor? Highly unlikely. And combined with the following other hidden tricks that can be done to any V-8 engine installed in a classic Ford (small-blocks, Clevelands, FEs and 429/460s included) this one might be the hidden mod that does the most, while at the same time shows the least.

More Compression
Building that stroker short-block (or even if you stay with a standard stroke engine like was done here with our 351W) and bumping up the compression a point or so is another totally invisible thing nobody will ever know about. When putting together a new engine for any Ford, consider ratios in the 9.5:1-10.5:1 range for a strong running combination that will run well with typical 91-93 octane pump gas.

Higher Spec Cam
Combined with a higher compression ratio, bigger cams play a part in making more power. Healthier cams are always invisible to the eye. But, of course, they’re readily apparent to the typical enthusiast ear once the engine is running. But you can always bluff a little, depending on how lopey the idle is.

Roller Rockers
Do you already have a stock engine in your car that runs good and doesn’t need the internal changes mandated by building a new engine with more compression and/or a stroker combination? If so, a valvetrain anchored by a good set of roller rockers such as these Comp Cams 1.6:1 ratio (standard 289/302/351W) rockers will always be hidden by the valvecovers. Combine these with a roller cam upgrade and you have the makings of a thoroughly modern valvetrain that’s decades ahead of what was offered in the ’60s and ’70s.

Eliminate Points
Another upgrade that’s invisible and uses the stock distributor housing, is eliminating the points and condenser, which is what a Pertronix Ignitor does. Doing away with the points and condenser used in stock Autolite and Motorcraft distributors should be near the top of anyone’s list of upgrades to make a car more daily-driver reliable–even if the car isn’t used that often.

Cylinder-Head Porting
This is another one that merits mention, simply because it’s so effective. Porting Ford cylinder heads for improved flow is a time-honored way to make more power. And, of course, it’s as invisible as can be. With no mention that you have ported heads on your car, it’s another one of those hidden mods that’s impossible to detect. Both aftermarket and stock heads (such as a ’69 351W casting) can be ported, but keep in mind that spending the time and money to port aftermarket heads will yield better results in the end that expending the same efforts on stock heads. And if you want to go with an ultra sneaky option for aftermarket aluminum (or cast-iron) heads, then consider painting them your car’s factory engine color to make them even less likely to be discovered.

Other Equipment
Moving to other parts of the car besides under the hood, there are several ways to improve upon a vintage Ford without it being apparent. Options here pertain to the drivetrain, brakes and suspension.

Overdrive Transmission with a Stock Shifter
In our opinion, this is the single best improvement that can be done to any ‘50s, ’60s or ’70s era Ford. For cars with automatics, a four-speed AOD is the way to go. For cars with three–or four-speed manuals, the shown T5 five-speed setup from Modern Driveline is an excellent option. Regardless whether your preference is for an automatic or a manual, as long as a transmission has an overdrive top gear you simply cannot go wrong with installing one in any Falcon, Fairlane, Galaxie or Mustang.

We’ve owned and/or driven several vintage Fords with AODs and five-speeds and the personality of the whole car is dramatically changed for the better. There isn’t any other single thing you can do to make a classic Ford so dramatically better to live with on a regular basis–especially if you do a lot of freeway driving.

Furthermore, with an automatic, AOD conversions can be done using the stock shifter such as in ’65-’73 Mustangs, so the upgrade remains totally hidden until the car shifts into top gear on the highway at 70 mph.
For five-speeds, stock-look shift handles such as available from California Pony Cars can be used to keep things unobtrusive. And if you run a shift knob that doesn’t have a five-speed pattern on it, nobody will ever know that your classic Ford car has the high-speed cruise capabilities that all new cars have today.

Rearend Gear Ratios and Limited-Slip Differentials
This is much like an overdrive transmission and the internal engine upgrades we’ve discussed--anything upgraded inside an 8- or a 9-inch rearend will always remain invisible to the naked eye. Limited-slip differentials of any description are a solid advancement, as are a set of lower (numerically higher) rearend gears–made all the more possible with the addition of a four-speed automatic or five-speed manual trans. For the majority of vintage Fords that most drive on a daily basis, ratios in the 3.00-3.70 range work very well. For any car with an AOD or T5, 3.00, 3.25 or 3.50 gears are a good choice. If you want more off-the-line punch, ratios in the 3.50-3.80 range are choices to consider. Just remember that the lower the gear (again, numerically higher) the more gas you’re going to use. For example expect about 10 percent less fuel mileage running a 3.25 gear, compared to a 3.00–whether you have an overdrive trans or not.

Suspension and Chassis
Yet another mod most will be hard-pressed to notice are suspension improvements. You’ll have to at least look under the car to discover anything. Different rate springs, better shocks, larger antisway bars and upgraded control arms all qualify. Subframe connectors are another thing to consider–especially if you have a convertible. While maybe a little easier to discover than say, an upgraded rearend, most suspension upgrades are still relatively stealthy and looking underneath the car is required to see them.

Not Totally Hidden
Slightly Larger Diameter Wheels
Most vintage Fords came with 13-, 14- or 15-inch wheels. Upgrading to a 15- or 16-inch wheel of some sort, or at the biggest a 17-inch on a bigger car is a subtle change that can be tough to detect. And if you stay with a 15-inch wheel on smaller cars like ’65-’66 Mustangs or a Falcon, that choice will usually be harder to distinguish. Anything 16 inches or bigger definitely stands out on smaller cars like ’65-’66 Mustangs or ’60-’65 Falcons.

Bigger cars like a Galaxie or a ’66-’67 Fairlane can easily accommodate a 16-inch wheel without it being real obvious, as along as wheel offset is correct and the tire isn’t too large. Also consider factory-style wheels, with the best example being a ’65-’67-type Mustang styled-steel wheel available from several sources in 15-inch sizes.

As far as tire sizes, our experience has shown us that on a 16x8-inch wheel, 225/50R16 and 245/50R16 tires fit well on ’67-and-newer Mustangs and the shown ’67 Fairlane, while several sizes fit nicely on 15-inch wheels for ’65-’66 Mustangs. These include 215/60R15s, 225/50R15s and 205/55R15s. These suggestions will look great, but most will still be subdued enough for many to overlook.

Rack and Pinion Steering
Not very visible unless you look under the car, this upgrade makes a huge difference in the way a vintage Ford behaves on the highway. If you want your car to be a true high-speed road-trip cruiser, a rack-and-pinion system such as shown from Total Control Products is a worthwhile option to consider.

If there was one area where you shouldn’t worry about whether the upgrade is hidden or not, it’s the brakes. However, most stock wheels hide brakes quite well. If your car has front drum brakes, a set of stock-type front disc brakes won’t normally generate much attention. However, if you want to go beyond that, but still maintain the hidden quality, Baer Brake Systems now has systems with PBR calipers and 11-inch rotors that will fit behind many stock-type 15-inch wheels. Stainless Steel Brakes also has these optional drilled and slotted rotors that are very difficult to detect behind the stock 14-inch styled-steel wheel on this ’67 Mustang.

Hiding in Plain Sight
Very popular engine upgrades that have always been effective are headers, an aftermarket intake and a four-barrel carburetor. While they’re a great way to go, they do have a drawback in the context of our discussion–you can readily see them with just a casual glance.
However, there are ways around this issue when it comes to these three components. For example if your classic Falcon, Fairlane, Galaxie or Mustang has a two-barrel, adding whatever four-barrel that would’ve come on the car for that year along with a factory cast-iron four-barrel intake are one way to hide the upgrade. An Autolite 4100 four-barrel on a ’65-’66 Mustang is a good example. Painting an aftermarket aluminum intake a factory engine color is also an effective trick, and combine that with the carb hidden under the air cleaner and you have these two items pretty much out of sight.

As for exhaust, one possibility is to Extrude Hone stock cast-iron manifolds to pick up a little extra power. And if you start with K-code manifolds, the results will, of course, be better than with log-style ones. Other than maybe a shorty design, most headers will be detectable. Headers are one of the more obvious underhood changes you can do, but with everything else that can be hidden, you could say they’re the only things you did to your car–until, that is, they hear that big lumpy cam.

Published Dec 7th, 2015

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