Steve Morris, of Steve Morris Engines, recently took a nostalgic ride to show everyone how cool old-school engine tuning is. In his latest video, he worked through a small block Chevy fitted with very challenging yet rewarding technology: mechanical fuel injection. As always, this complex system, a classic technology that predates electronic fuel injection systems, demands a level of knowledge in engine dynamics and a quite deft touch when it comes to tuning. Morris’s mission: to wring over 800 horsepower out of the classic power plant.

Mechanical Ease: A Symphony of Valves and Linkages

Unlike modern computer-controlled engines, mechanical fuel injection systems rely on a web of precision-calibrated valves, jets, and linkages to inject just the right amount of fuel into each cylinder. Morris began by priming the system and making opening adjustments to throttle blades and the all-important “barrel valve.” The latter controls the flow of fuel in much the same way a faucet regulates flow based on the position of its throttle linkage.

Troubleshooting: When One Bank Falls Silent

An all-too-common problem presented itself early: one bank of cylinders failed to fire. Morris, with many years of experience, quickly diagnosed the problem: an improperly set-up throttle linkage. He then carefully adjusted the linkage until each cylinder received the right air-fuel mixture and brought the engine to a harmonious roar.

A Paper-Thin Precise Art

Idling engine with mechanical injection is an art of fine balance. Morris did this with an astonishingly simple tool —a very thin feeler gauge made of paper — which he used to precisely set the throttle blade openings. This shows how extremely sensitive the system is. There can be a verifiable change in behavior in response to tiny alterations.

Fuel Curve Control: The Role of the Main Jet

Morris further explained the role of the “main jet” that was instrumental in controlling the delivery of fuel to the engine in general. By changing this jet, he showed how the entire fuel curve can be adjusted, affecting the engine’s power output across the RPM range. It was a graphic example of how everything — or at least, in mechanical terms, as much of it as was currently known — fit together.

The High-Speed Bypass: A Crucial Oversight

In a flash of “aha,” Morris stumbled over a previously overlooked blunder that would have cost the engine dearly: The “high-speed bypass” had not been properly adjusted. This bypass adjusts the fuel flow at the high end of the RPM range. The mistake proved just how valuable an added double-check is, even for the most experienced pros. With that sorted out, the engine came into its own with a glorious serenade.

Dyno Discoveries and Final Touches

Mounted on the dyno, the small block Chevy finally revealed its potential, but Morris had another thing coming. He kept honing and adjusting with the main jet and ignition timing to get that perfect balance between power and efficiency. Throughout this whole process, he clearly explains the function of each component and the reasoning behind his tuning decisions.

A Testimony of Old-School Skill

This video is much more than just a tutorial on engine tuning. It is a tribute to the lasting power of old-school mechanical know-how. Where computer-controlled systems hold sway, Steve Morris reminded us there’s still a method to the madness — to understand and unlock maximum performance from classic technologies. Skill, passion, and the always exciting attraction of a perfectly tuned small block Chevy are demonstrated in this captivating exercise.