Car Culture & Entertainment

Pontiac’s Innovative OHC Sprint Inline 6 Proved That You Didn’t Need to Bring a V8 to the Musclecar Party

It’s always nice to see a Tempest that hasn’t been converted into a GTO clone—especially if it’s packin’ a Sprint 6. (Image/OnAllCylinders)

In an earlier article on the Crosley Hotshot, we mentioned that it carried a groundbreaking engine with an overhead camshaft. That got us thinking about another innovative OHC powerplant that arrived over two decades later.

And when we saw a Montero Red Pontiac Tempest with the distinct “OHC 6 Sprint” badging at the 2021 Goodguys Summit Racing Nationals a few weeks ago, we figured now was a good time to tell you about it.

The OHC Inspiration

As with other performance-focused GM efforts like the Cosworth Vega and Pontiac GTO, the Sprint 6 story begins with John DeLorean.

And just like he did with the aforementioned GTO and Vega, DeLorean looked to Europe. He noted that cars like the Jaguar E-Type were powered by engines running overhead camshafts. This OHC design not only reduced the number of moving parts in the engine, it improved valvetrain performance and allowed for better valve sizing and spacing, which often meant a wider usable rev range and improved flow.

Always the engineer, DeLorean sought to develop a similar overhead cam engine that could create V8 power with less cylinders, in a lighter, more compact package.

Visually striking, it’s easy to spot Pontiac’s OHC six thanks to its ribbed valve cover/cam carrier and timing belt cover. (Image/OnAllCylinders)

Enter the Pontiac Overhead Cam Sixes

Starting with the basic engine architecture from Chevy’s inline six, Pontiac engineers pretty much reworked the entire thing. In addition to an all-new iron engine block, the Sprint 6 had a unique cylinder head that put a single, large 1.920″ intake and 1.600″ exhaust valve in each combustion chamber.

The camshaft, fuel pump, oil pump, and distributor were all driven off a fiberglass-reinforced Gilmer belt—a considerable innovation for the time. That arrangement also resulted in the Sprint 6’s signature ribbed timing belt cover that pops over the engine.

It’s also worth noting that the Pontiac OHC isn’t an interference engine, meaning that a broken or stretched belt wouldn’t necessarily result in contact between valves or the piston, avoiding catastrophic damage.

And it gets even more interesting when you look at the Sprint 6’s valve cover. It completely housed the single overhead camshaft within integrated journals, and the whole thing fit directly atop the cylinder head and valves. For valvetrain service, you disconnected the belt and removed the entire assembly just like a traditional valve cover.

Pontiac wasn’t shy about announcing its new powerplant either—all Sprint-equipped cars got special badging. (Image/Summit Racing)

Pontiac OHC & Sprint 6 Performance

It’s important to note that, while they all had the same overhead cam design, only the performance variants of the Pontiac OHC inline sixes got the “Sprint” name.

Base-trim OHC sixes were equipped with a single one-barrel carburetor and made around 130 horsepower. Sprint sixes benefitted from a hotter cam, Rochester Quadrajet, and a few other enhancements to push engine output well north of 200 horsepower.

In top fighting trim under the hood of a 1967 Firebird, the Sprint 6 made 215 hp. For comparison, the Firebird’s base 326 V8 was making 250 hp that same year. At its peak, the 1969 Sprint 6 topped out at 230 hp.

Famed tuning shop Royal Pontiac even offered a hop-up kit for the Sprint motors and, when tested on the drag strip, that extra performance could easily put you into the 14s.

In addition to the Tempest and LeMans midsize cars, Pontiac made its Sprint engines available in its all-new Firebird as well. Note the small OHC 6 emblem on the rocker behind the front wheel. (Image/MidCentArc, Creative Commons)

The End of the Pontiac OHC Sixes

Despite some growing pains (oil starvation on the valvetrain being one of the biggest), these motors were showing that they could be capable and reliable performers. Yet, Pontiac only produced its OHC six engines from 1966 to 1969.

Why the short run? It was probably due to a confluence of issues, including mechanics’ unfamiliarity with the OHC design, high development costs, cheap gas negating the need for efficiency, and the overall perception that V8s offered inherently better performance (and to be fair, at that time, they did).

Piston-Powered-Auto-Rama-Tempest
Amid a sea of V8s, an OHC inline six certainly stands out. (Image/OnAllCylinders)

Though it’s fun to wonder what Pontiac’s overhead cam engines would have evolved into, given more development time. Perhaps the Sprint sixes would’ve propelled Pontiac through the gas crisis of the 1970s better than its V8s? Perhaps an overhead camshaft engine could’ve turned the Fiero into the Ferrari fighter it should’ve been?

Regardless, these OHC Sprint engines are a fascinating footnote in Pontiac’s history—so at your next car show or cruise-in, be on the lookout for these powerplants under the hoods of first-gen Firebirds and 1966-69 Tempest/LeMans models.

Like obscure Pontiac engines? You’ll probably dig this: The 1980-81 Pontiac Turbo Trans Am was an Evolutionary Step in GM’s Forced Induction Engine Development

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11 Comments

  1. Pingback: Facts and Information About the Chevy Inline Six Engine

  2. Glenn Spears says:

    I had a ’67 tempest w/ohc 6
    Manual shift and AC.
    I put Gabriel high jackers and chrome reverse rims on it.
    Midas gold w/black painted top.
    I rolled it over Thursday August 10, 1972.

  3. I had a 66 sprint with a Muncie tranny and more than one small block owner learned it was quick!

  4. Schon Crouse says:

    Thank you for noticing our car. We had so many comments about keeping the car original.
    This is a very nice article

  5. John Watkins says:

    I had 67 Lemans Sprint 6 4 speed post car. Drove over 120k miles but sold in 1975. It became difficult to find premium fuel at rural stations. (10.5 Cr dictated premium). My job required a lot of driving.
    It was purchased in 68 as senior in college. I got Navy commission out of OSU. While on active duty it made many trips between Columbus and the coasts. Great car and fun to drive!

  6. Mike Friday says:

    I bought a 1967 Lemans with the OHC6 back in the’80s. It was a bit dopey until I put a 4:11 rear under it. It woke it up considerably, and the OHC didn’t mind the high revs at all. It had the ST300 two-speed auto.

  7. I bought a new 69 sprint with 3speed hurst. Loved it but sold it in 73. Last year bought a running sprint engine out of a 68 firebird that was being converted to retro mod. Still searching for a roller to put it in.

    As mentioned in article, I also own a very rare Cosworth Vega #3241

  8. James Frazier says:

    I have a 66 tempest sprint with 3 speed on floor. Bought from original owner who got her groceries with it. 52000 miles. Had in storage for years now. Hoping to start a restoration on it next year.

  9. Didn’t somebody develop a centrigal advance variable camshaft setup for these?

  10. Have 69 Firebird convertible. Dad was original owner, stayed in family. 86,000 mi. Restored in 1982, original interior. 4 speed with higher torque rear end. Loaded with options…Dad was always trying to get something no one else had.

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