Because we have performed a number of six to V-8 conversions in this magazine's 30-year history, you'd think we'd have it all down to a methodical process. However, each and every project brings its own challenges. Our '67 hardtop was no exception. We learned to plan better for one thing. We installed a JMC Motorsports hydraulic clutch along with a Master Power brake booster and discovered quickly the two will not work well together no matter what kind of modifications are made. That's when we went to a Modern Driveline cable clutch and Trans Am Racing power brake booster instead. Both cleared each other nicely.
We also learned about exhaust systems, headers, and pipe size. We needed a stock 2- or 2 ¼-inch dual exhaust system from Virginia Classic Mustang instead of the JBA system we ultimately went with. The JBA system is terrific and offers perfect fit. What's more, it yields a throaty bark with minimal backpressure. However, the JBA system is designed more for 400-500-horse small-block engines due to its 2 ½-inch pipes and straight-through mufflers.
Ride height is another issue we didn't address until the car was complete. We needed five-leaf mid-eye springs for more acceptable ride height. We went with four-leaf mid-eye and got less ride height than we bargained for.
The best advice we can offer to readers contemplating a six to eight conversion is to plan ahead and do your homework beforehand.
 The PerTronix Ignitor and...  The PerTronix Ignitor and Ignitor II have been around for more than a decade. They remain the best single modification you can make to a classic Mustang. The Ignitor hides nicely inside an Autolite or Motorcraft distributor. It installs in 30 minutes. And it improves starting and drivability. If you're running a PerTronix Flamethrower coil, remember to bypass the pink factory resistor wire from the ignition switch. And always remember to keep your distributor's ground wire connected. |  We used an Edelbrock high-flow...  We used an Edelbrock high-flow water pump on our Trans Am Racing 289. In the extreme heat of Southern California in summer, there have been no overheats. A high-flow water pump isn't about pressure, but volume. It increases coolant volume and flow through the engine's water jackets, which carries heat away to the radiator. |  Although common logic has...  Although common logic has always been to run a low-pressure radiator cap on old cars, you need at least a 16-pound cap if everything is new. A 16-pound cap raises your cooling system's boiling point, which prevents boil over. |
 Although this common six-blade...  Although this common six-blade fan for air conditioned applications moves a lot of air, it is an inefficient cooling fan. It consumes a lot of power and makes a lot of noise. |  The most efficient cooling...  The most efficient cooling fan is the thermostatic clutch fan. They work as needed when the radiator gets hot. |  It engages and cools, then...  It engages and cools, then disengages and freewheels when it isn't needed, which helps free up power. |
 Next to lubrication, your...  Next to lubrication, your Mustang's most important support system is engine cooling. When you're doing a six to eight swap, do not miss this important cue. |  Reward your engine with a...  Reward your engine with a healthy cooling system -- new four-row core radiator, new hoses, the best stainless steel clamps, 180-degree thermostat, high-flow water pump, deep breathing fan (flex fan or thermostatic clutch fan) and shroud, and an anti-collapse spring in the lower radiator hose. | |