“Plymouth Radial Air” Pickup Smokes Leno’s Garage

Sometimes you do things because you can. When you’ve got a 1939 Plymouth pickup and a Jacobs seven-cylinder radial engine from a Cessna airplane sitting in the same wrecking yard, you do a mashup. Right? 

Gary Corns has a Denver wrecking yard that’s been around since the 1950s. Wrecking yards accumulate all kinds of hunks of metal over the decades. Corns knew he wanted to rejuvenate the pickup someday. After all, it’s a rare Plymouth truck.

Yes, Plymouth Made Pickup Trucks

Plymouth Radial Air | Jay Leno’s Garage

Plymouth mostly made passenger cars. But, in the late-1930s up to WWII it took pickups from sister company Dodge and branded them as Plymouth so it would have trucks to sell, also. From the looks of it, the Plymouth was obviously nice enough not to scrap.

When Corns started eyeing the radial engine he and some buddies started riffing on the engine. Then they dragged the Plymouth into the shop and hatched this plan. The “Plymouth Radial Air” truck was born. With the help of friends, his two sons, and almost two years of wrenching, this is what emerged from his shop.

These 300 hp Jacobs radials were manufactured in Pottstown, Pennsylvania, not too far from Bethlehem Steel. Cessna stabbed these L-5 seven-cylinder engines into its planes until the late-1950s. Jacobs innovated forged aluminum pistons, sodium-filled exhaust valves, and magnesium crankcases. All of these components were developed for lightweight combined with a fail-proof design. 

The Engine Was Called “Shakey Jake” For A Reason

The Jacobs L-5 engine was called “Shakey Jake” for its extreme vibration at low RPM. You’ll see that when they start it up outside of Jay Leno’s garage in the attached video. The 757 ci radial has been adapted to a GM TH400 automatic transmission. These transmissions were found in millions of GM products throughout the 1960s to 1990s. 

The engine and trans are connected by a large belt tied to a V-drive out of Corn’s own boat. It’s a pretty slick way of transferring all that power to the rear wheels. So, the Radial Air has some aircraft, automotive, and boat components all wrapped together. Is everything covered? 

The pickup obviously exhibits some nice engineering and craftsmanship. The aircraft theme carries through into the cockpit featuring tons of rivets and eve dual controls. The lever between the seats controls engine throttle. 

Radial Air Equipped With “Stunt Smoke”

Plymouth Radial Air | Jay Leno’s Garage

“Stunt smoke emits from a three-gallon tank to add a smoky mist to the proceedings. Corn wanted this for effect. After the exhaust warms up the tank injects the oil onto the exhaust for that smoky start we all love to see and breathe. 

The plan was for the truck to run at Speed Week at the Bonneville Salt Flats. Unfortunately, the truck didn’t pass technical inspection. The seats were not properly bolted into the roll cage. So, Corn and his sons started it up and drove it along the track to the delight of the participants. Hopefully, he’ll be back to for a sure record as we can’t imagine there is another vehicle running in the Radial Engine class if there is such a thing.