Video: The Problematic 426 Hemi Is Back On The Engine Dyno

The last video we posted of a 426 Hemi being dyno tested and tuned in search of 550 horsepower at Nick’s Garage ended on a sour note, as a number of gremlins reared their ugly head, and prevented Nick Panaritis from reaching the power goal set for the mild rebuild of his customer’s 1966 426 Hemi engine. It was also a cliff-hanger that some of you really didn’t like, so in the spirit of closure, we bring you the follow-up.

This video takes place a week later – a gap in time necessitated by the amount of time it takes for parts to arrive at his shop in Quebec, Canada. After installing a new set of heavier-wall pushrods to combat the deflection Panaritis believed was responsible for the lack of power, and changing the gears in the oil pump, the team was ready to once again make some power runs on the dyno.

After a quick first pull, in which the valvetrain noise seems to have disappeared, Panaritis rejets the carburetor to richen the air/fuel ratio up. He then adjusts timing with the new AFR, and runs into issues with the engine stumbling, continuing this engine’s history of being particularly problematic. The new ignition wires he mentioned ordering in the last video are installed, and that seems to cure the stumbling and hesitating issue and get the Hemi running smoothly again.

Apparently, that was just the ticket, because on the next dyno pull, the team was rewarded with the number they had been looking for – 553 horsepower at 6,200 rpm and 519 lb-ft of torque at 4,700 rpm. So while this wasn’t the usual, heavily-edited process usually shown to the world, this journey is an honest look at how projects usually go. In the real world, there are delays, setbacks, and challenges to be overcome, and being able to handle those challenges is an underrated skillset that goes largely unnoticed by the general public.

After swapping the pushrods for stiffer-wall versions, and changing out the low-mile factory plug wires for new performance pieces, the Hemi finally started cooperating, posting 553 horsepower at 6,200 rpm, and 519 lb-ft of torque at 4,700 rpm. Just as Nick predicted.

About the author

Greg Acosta

Greg has spent over a decade in automotive publishing as Senior Editor of Race Pages magazine. In his free time, he is a firearms instructor and volunteer in the police armory.
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