TECH QUICKIE: What is a ‘3/4 Race’ Camshaft?

Occasionally the term “¾ race cam” pops up in conversation, usually with veteran hot rodders or nostalgia groups. Sometimes you’ll see it in print ads and online product listings. From a purely technical viewpoint it means little in the way of explaining a camshaft’s performance potential. It’s just one of those glorious reminders of the early days when camshaft grinders had furious rivalries on the track and in the media. It’s also a significant milestone in a developing enterprise that snowballed into what we now recognize as the street-performance market.

The original 3/4 race cams are the forerunners of today’s street-performance grinds.

The term likely originated in the ‘50s as the burgeoning hot-rod industry was modifying Ford Flatheads to drag race on airport runways and attempt top-speed runs on dry lake beds. The legendary Ed Winfield was one the early pioneers in grinding camshafts with more aggressive lobe profiles, and the cams were often labeled as full race for promotional purposes.

“And then some guys wanted a milder cam that could also be used on the street, so they called it a three-quarter race cam because it didn’t have as much duration and lift,” explains John MacKichan of the Speedway Motors Museum of American Speed in Lincoln, Nebraska.

Ford Flatheads were the beneficiaries of the first 3/4 race camshaft grinds.

You have to remember that tooling up the master lobe that was necessary to regrind an existing camshaft core was quite involved. For performance engine builders in the ‘50s and ‘60s, there were only a handful of camshafts for even the most popular engines. In fact, some cam grinds were blessed with their own nicknames that are still revered as iconic hot rod hardware today, such as the Duntov cam (3736097) for small-block Chevys and the Le Mans cam (C7FE-6250-A) for Ford small-blocks.

Remembering the ‘cam wars’

When the great cam wars started in the ‘60s, the term “¾ race” was so recognizable as a performance model somewhere between full race and mild stock performance that it seemed like the perfect fit for any hot rodder. As the market expanded in both applications and more grinds for each of those engines, the term slowly lost much of its meaning. Now you can order grinds specific for nitrous, boost, low-end torque or even just a lumpy idle.

Here’s an engine from the Museum of American Speed in Lincoln, Nebraska, that likely sports a 3/4 race cam along with its 6-pack of Strombergs.

“The modern equivalent would be the Stage 1, Stage 2 and Stage 3 type cams that were popular in the Import/Sport Compact world of the late ‘90s,” explains Billy Godbold of Comp Cams. “It really doesn’t mean anything.”

In fact, Godbold says one of the major players in those legendary cam wars despised the designation.

“Harvey Crane hated the three-quarter term,” says Godbold, who was very close to Crane before he passed away in 2013. “I think the term three-quarter was around even before the real cam wars begun.

Some advertisements and online listings still refer to 3/4 cam grinds.

“If you go back before the mid ‘60s, all the aftermarket cams were just bigger versions of the OEM profiles with more lift and duration,” continues Godbold. “What set Harvey apart from that generation was that Harvey redesigned everything from below the lash point up to max lift. The other guys probably did not have the math background, and no one had the required design software.

“Hence, the old ¾ race camshaft was just an in-between duration and lift version of the street Flathead and race Flathead,” sums up Godbold, adding that “by the time Comp was born, the 3/4 deal was dead as a hammer.”

About the author

Mike Magda

Mike Magda is a veteran automotive writer with credits in publications such as Racecar Engineering, Hot Rod, Engine Technology International, Motor Trend, Automobile, Automotive Testing Technology and Professional Motorsport World.
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