1967 GTX 440 Big Block Restored and Tested

At Nick’s Garage, the dyno room is where every build finally tells the truth — but this time the dyno itself breaks down, and the whole shop grinds to a halt. Waiting in the wings is a freshly restored 1967 Plymouth GTX packing a 440 big block that needs to be tested and tuned. Can Nick and the crew get the equipment running before the star of the show gets its moment? Find out whether the GTX makes the numbers it was built for.

A dyno room is a place built for a single purpose: to end arguments. Every build gets strapped down, run up through the rpm, and forced to prove its power at the wheels rather than in someone’s imagination. At Nick’s Garage that room is where the action is — until the dyno itself breaks down and the entire shop grinds to a halt. Waiting through the delay is a beautifully restored 1967 Plymouth GTX with a 440 big block that has been rebuilt and is ready to be tested. Whether the crew can revive their own equipment in time to give the car its moment is the tension the whole episode runs on.

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The 440 That Defined the Gentleman’s Muscle Car

The 1967 GTX earned a nickname worth remembering: the gentleman’s muscle car. Plymouth built it as a premium, purpose-designed performance model rather than a stripped-down budget special, and it came standard with the 440 Super Commando V8. That big block made 375 horsepower and a genuinely enormous slug of torque, giving the GTX effortless, big-cube grunt without the temperament of the pricier 426 Hemi option. It was fast, it was refined for its era, and it looked the part with its subtle performance cues.

When the Dyno Room Goes Dark

The drama here is that none of that matters until the dyno cooperates. When the equipment fails, everything downstream stops — the tuning, the testing, the payoff the whole build has been pointing toward. Anyone who has worked in a shop knows the specific frustration of a tool breaking at the worst possible moment, and Nick and the boys have to diagnose and fix their own machinery before they can even think about pulling the trigger on the GTX.

The Moment of Truth

That is what makes the eventual run so satisfying. A 440 that has just been through a full restoration is an unknown quantity until the rollers spin, and the dyno sheet is the honest verdict on all the work that went into it. Does the freshly rebuilt Super Commando deliver the numbers a healthy 440 should? That is the exact question the machine was strapped down to answer, and it is worth watching the crew earn the result. Watch the full video and share your thoughts below.

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