Jim Smart
February 1, 2009

Mustangs are closely tied to V-8 engines, and it's been that way for nearly a half-century. However, six-cylinder Mustangs reign supreme when it comes to raw production numbers. Ford built a lot of them, encouraging dealers to sell even more when V-8 engines were in short supply during the mid-'60s. Buyers snapped them up in great numbers just to get into a Mustang.

With so many six-cylinder Mustangs out there, why aren't we building more of them today? As a rule, enthusiasts like the way a V-8 sounds and responds. But what if you want something that doesn't require radical surgery?

When it's time to buy a Mustang, six-cylinder hardtops are the cheapest available, making them terrific restomod bargain rides. When you build a six-cylinder Mustang, you're building something different. It isn't just another V-8 Mustang, but rather something with a lot of room for imagination because inline engines look sharp when they're dressed to the nines. A six built with an array of goodies from Classic Inlines provides an engine compartment nearly everyone will stop to admire.

This is a 250ci block being built for a turbocharged application by McLearran Racing in Southern Arizona. Notice the O-ring sealing around each bore for an artificially aspirated (turbo or supercharged) application. The 250 is long on torque thanks to its generous stroke.

Build a classic Ford six intelligently and it will sport a throaty European sound. By the way, inline Ford sixes don't have to sound buzzy. Give them an Italian opera tenor voice with the right induction, cam profile, cylinder head, and exhaust tuning. Along with the right exhaust tuning, your Mustang six will come alive.

Some History
The Mustang's "Getaway Six" was originally known as the "Thrift Power Six" before it became known as the Falcon Six. When the compact, lightweight Thrift Power Six was introduced in the fall of 1959 in the all-new '60 Falcon, there was only one displacement: 144 ci with a 3.50-inch bore and 2.50-inch stroke sporting 90 hp. The 144 wasn't much on torque. In fact, it was a gutless wonder that needed a good running start, but it was certainly practical for any commute. A year later, Ford stroked the 144 to 170 ci for 1961, giving the Falcon a pinch more punch at 105 hp.

The 250ci six has main bearing journals that are the same size as those in the 289/302ci small-block V-8. That, coupled with seven-main bearing construction, makes the Mustang's largest six quite rugged and easy to build. When you build a Ford six, you can make the same improvements as you would with a V-8: chamfer the oil passages, dynamic-balance the bottom end, recondition and shot-peen the connecting rods, install ARP rod bolts, opt for forged pistons if you're going to spin it high, install hardened exhaust valve seats, increase rocker arm ratio, choose the right performance camshaft, and improve breathing.

Ford increased the 144/170 bore and stroke to 3.86/3.126 inches in 1963 to create 200 ci with 120 hp and 190 lb-ft of torque. Originally, the 200 six had four main journals like the 144 and 170, but Ford made significant block improvements for 1964, including seven main bearings to eliminate crank oscillation, which had caused noise, vibration, and harshness. You can tell the difference between a four-main bearing and seven-main bearing block by the number of core plugs. Four-main bearing blocks have three while the later seven-main bearing blocks have five. Seven-main bearing blocks also have hydraulic lifters instead of the solids used with four-main bearing blocks.

A lame cylinder head with an integral intake manifold and a mix of Autolite, Holley, and Carter one-barrel carburetors greatly limited the 144/170/200ci engines. Because the integral log manifold was a raw, unmachined casting inside, fuel distribution was never a strong suit with these engines. Most didn't idle well and throttle response was poor at best.

Ford took the 200ci six's architecture and raised the block deck 1.66 inches in order to reach 250 ci for 1969. To achieve the extra 50 ci, Ford increased the stroke to 3.91 inches, which improved torque to 240 lb-ft. What made the 250 different from previous sixes was its larger main journal, bolt-on intake manifold, and bellhousing/starter arrangement like a small-block V-8. It also had a new cylinder head for improved breathing and easier service. Available in the Mustang from '69 to '73, the 250 remained in production through 1976 in other Fords.