Isaac Mion
April 24, 2012

Michael Cox is an airplane mechanic by trade, so it's no surprise that on nights and weekends, he builds objects that fly across the ground. Like most of us, Cox has been into cars, particularly Fords, since he was in high school. He's been racing them for more than 16 years and has owned just as many. His first foray into vintage racing took place back when he campaigned a '67 Mustang Coupe in the RMVR (Rocky Mountain Vintage Racing) series.

"I bought the SportsRoof from a friend of mine in 2004," said Cox. "It had been sitting in his backyard for years and he was looking to get rid of it. Around the same time, another racer from RMVR approached me about buying my Mustang coupe. So, I figured it would be a good time to sell."

It also happened that the gentleman who bought the coupe already had an engine, so Cox was able to keep the balanced and blueprinted 289 that he had assembled himself. The Block Shop in Denver, Colorado, performed all of the machine work so Cox could drop a billet steel crankshaft and custom pistons into the 12:1 compression small-block. Power output is an estimated 400 hp at 7,000 rpm, thanks in part to a host of other accoutrements like FPA step headers, a Holley carb, and an Edelbrock Performer RPM intake among others. Of course, being on the track, Cox has plenty of time to keep the revs near seven grand. In fact, when we spied him at local car show, he had to leave early, as the Boss 302 clone is understandably temperamental at slow speeds, which they tend to be when exiting a car show. The duration on the Crane cam probably doesn't help at these speeds either. But we're getting ahead of ourselves.

Before Cox could take the car to the 2010 RMVR Trans Am invitational, he had to get the car completed. When he acquired it from his buddy, Cox told us that the SportsRoof was in rough shape, but nonetheless repairable.

"After repairing some rust in the floorpans and quarter-panels, I enlisted the help of my friend and fellow racer, Jim Valdez, to build the mild steel, eight-point rollcage," said Cox. "The interior and bodywork I pretty much did at the same time. I would work on one thing until I got sick of it, then I would work on something else until I got sick of that. It wasn't really a well-planned build."

By the way, we should mention that one of those things that Cox completed during this period was the installation of the Ford 9-inch rearend, Ford '70 Top Loader transmission, and Detroit locker that he had laying around his shop. After jumping around from spot to spot on the project, Cox decided to take the car to bodyman and friend Bob Hill in Colorado Springs.

"He set about correcting all the mistakes I made during my attempts at body panel replacement," said Cox. "I was making the trip to the Springs regularly to help Bob with the body and paint. By that I mean I was doing the stuff that didn't require any skill, like rough sanding and cleaning up. Bob let me spray one of the doorjambs, but after about two passes with the gun he said, ‘Give me that back. You're making me nervous.' So I can say I painted about 8 inches of the car."

After the car came back from the Springs, it was crunch time. Not for sit-ups, but to have the car ready for the upcoming Trans Am race which would arrive in approximately two months time. Cox wired the car up to his satisfaction in about three weeks, but the deadline soon started to bite at his heels a bit. He called upon his friend, John Cummings, an old-school drag racer, yet someone obviously knowledgeable in making cars go fast.

"I think he really enjoyed the challenge of assembling a road race car, which was something he was not familiar with," said Cox. "With John's help, we got the car finished one day before the race."

With no time to spare, Cox was well aware that there would be a few things to sort out after a shakedown run.

"I knew there would be some teething issues and I wasn't disappointed," said Cox.

Once at the track, Cox approached the car with a mixture of excitement and trepidation. He opened the door, passed the shiny aluminum door panel, and climbed into the Sabelt race seat before buckling the five-point Simpson race harness and shooting a steely-eyed, furtive glance at the Auto Meter gauges set in the custom-made aluminum dash. A nasty, yet somehow Siren-like song, emanated from the Spin Tech mufflers and 2-1/2-inch custom exhaust as Cox fired up the previously mentioned small-block. He put his hand on the Hurst shifter, knocked it into gear, and started through the pits for a shakedown run.

"I just went slow to make sure everything felt like it would stay together," Cox said. Feeling relatively good about the Mustang, Cox picked up the pace, letting the leaf springs from EPS and Koni adjustable shocks, and front stock-type coil springs in the front handle the more aggressive loads in the corners. As he applied the brakes at the end of the first straight, he realized the 12-inch brakes up front grabbed a lot less than the 10-3/4-inch Lincoln Continental brakes out back.

"That's when I realized the brake bias was way out of balance, but I managed to keep it on the track," said Cox. "When I got the car back to the pits, I noticed the rear wheels were covered with gear oil. That is when I learned that I needed inner axle seals with the full floater rearend."

Being the uber mechanic that he is, Cox got things sorted out. But during qualifying, about six turns into the first lap, he pushed the clutch pedal down and it didn't come back.

"I had decided to use a hydraulic clutch to save some space under the hood and wouldn't you know, I put in a defective master cylinder," Cox said. "At that point, I felt like that was enough, so I became a spectator for the weekend. The car came home in one piece, so I considered it a moral victory."

Throughout the next few months, Cox solved a few other problems that still lingered, like a loose steering box, as well as the ones he "discovered" on his day out at the track. To solve the clutch issues, he fabricated a different slave cylinder arrangement that not only works a little better, but it's easier to maintain. As far as those brakes locking up, he took care of that by adjusting the bias and changing the brake pad compounds--one can imagine his neighbors liked that little test and tune session. Cox mentioned that one of the few last glitches he needs to sort out is getting his engine to rev up quick enough to get downshifts smooth. "Once I get that worked out, I won't have any excuse left for why I'm not faster," he said.

Michael Cox's Pony clone may not have the proper Boss 302 motor--he promises to get one soon--but what it lacks in pure muscle, it makes up for with heart and character; the kind that can only come from a build finished with the hard work of numerous friends and some serious trackside troubleshooting.

The Details

Michael Cox's '70 Mustang SportsRoof

Engine

  • '67 Ford V-8 289 ci
  • 4.00-inch bore
  • 2.87-inch stroke
  • Billet steel crankshaft
  • Custom pistons
  • 12:1 compression ratio
  • '69 Ford 351 Windsor cast-iron cylinder heads
  • Edelbrock Performer RPM intake manifold
  • Holley 4150 750-cfm carburetor
  • Ron Davis radiator, aluminum water pump
  • MSD 6AL ignition
  • 400 hp at 7,000 rpm

Transmission

  • '70 Ford Top Loader four-speed
  • Hurst Competition Plus shifter
  • 10.5-inch diaphragm clutch

Rearend

  • Ford 9-inch rearend
  • 3.89-4:86 ratio depending on usage
  • Detroit Locker differential
  • 31-spline Speedway Engineering axles
  • Coleman Racing Products full floater

Exhaust

  • Ford Powertrain Applications step headers with 1-5/8 - 1-3/4-inch primaries and 3-inch collectors
  • Custom 2-1/2-inch exhaust with X-pipe and Spintech mufflers

Suspension

  • Front: Stock-type coil springs and spindles, Koni single-adjustable shocks
  • Rear: Evergreen Performance Systems leaf springs and Override axle damper system, Koni shocks, Fays2 Watt's link

Brakes

  • Front: Ford disc, Kelsey Hayes four-piston calipers, 12-inch rotors
  • Rear: Ford disc, Kelsey Hayes four-piston calipers, 10-3/4-inch rotors from a Lincoln Continental
  • Ford 1-1/8-inch master cylinder

Wheels

  • Front: Performance Superlite or Minilite, 15x8
  • Rear: Performance Superlite or Minilite, 15x8

Tires

  • Front: Hoosier Street T.D. S, 25.5x8.5-15
  • Rear: Hoosier Street T.D. S, 26.5x9.5-15

Interior

  • Custom-made aluminum dash, Auto Meter instruments, Sabelt race seat, aluminum door panels, Simpson five-point harness, eight-point mild steel rollbar fabricated by Mike Cox and Jim Valdez

Exterior

  • PPG single-stage Grabber Blue and Black paint, headlights removed, Raydyot replica mirrors, Maier fiberglass front and rear bumpers, fabricated front splitter