The 1970 Pontiac Grand Prix isn’t a car that comes to mind when you think street beast.
They were decent performers with the legendary Pontiac 455 under the hood, but 1970 was full of muscle cars with big numbers.
This 1970 Pontiac Grand Prix would thump every one of them.
Marty Cochrane has owned this big Poncho for over 38 years. This car has evolved over the years from a daily driver to a track car and back.
Marty explained how the Pontiac was a daily driver for his wife in its original version, but a spin on an icy October street convinced her she didn’t want it as a winter car. That was in 1988 after Marty had restored the car to factory specs.
The game changed after that because Marty is a more-power guy, so he built the 455 for track duty and stripped the car. Things like side glass and power windows were shed to get the Pontiac into a more favorable track weight.
That all happened when Marty was a younger, fully-committed-to-track-performance owner so the Pontiac did everything he asked at the time. He was happy with a purpose-built car but then he wanted to move into the next phase for the Grand Prix.
Marty’s vision was to blend the factory version of a 1970 Pontiac Grand Prix with a beastly version of a 1970 Pontiac Grand Prix. In other words, he wanted a comfortable, civilized car with the heart of a lion.
This was no easy task because the track version of the car was so far removed from stock. The windows were gone and replaced with Lexan glass, so he had to refit factory glass on the Poncho and put the power windows back on the car.
The 455 was replaced with a monster 525 cubic inch big block that pumps out–in Marty’s own words, “WAY more than 725 horsepower”, so this version definitely didn’t step down in power.
The suspension has been tweaked to 4-link setup, and there’s a Dana 60 rear end to handle the brute force of the massive big-block under the hood. Marty did something unusual with the exhaust system—he added catalytic convertors.
He was tired of the exhaust smell when he was working on the car, so Marty wanted to clean it up. In fact, he believes it’s clean enough to be emissions compliant. That’s not a road many car builders go down, but Marty had his own game plan.
The paint job is another great feature of this ’70 Grand Prix. There’s a black base coat with an Ice Pearl finish. Marty said he, “only needed a cup of pearl” to get the job done—the results speak for themselves.
This car is not a sleeper—the hood and full roll cage give it away. But it is a very civilized driver in Marty’s opinion and that was his goal. The Turbo 400 automatic still has a line lock and trans brake, but it’s driver not a racer. The plastic fuel cell was replaced with a steel one because Marty’s buddy had a plastic cell disintegrate after a crash in regular street traffic.
Marty said he can light up the tires with ease, but the 1000-dollar tires hold him back. He said it has done an 11-second ¼ mile and it’s fully capable of cracking 10 seconds but that’s not the end game.
Marty is prouder that this car can get 13-15 miles per gallon at 60 miles per hour and he summed it up this way.
“I have evolved and the car has evolved”.
Marty Cochrane
By: Jerry Sutherland
Jerry Sutherland is a veteran automotive writer with a primary focus on the collector car hobby. His work has been published in many outlets and publications, including the National Post, Calgary Herald, Edmonton Journal, Ottawa Citizen, Montreal Gazette, Saskatoon StarPhoenix, Regina Leader-Post, Vancouver Sun and The Truth About Cars. He is also a regular contributor to Auto Roundup Publications.
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