Dropping a 12.4 litre Jacobs R-755 radial engine into a 1939 Plymouth pickup truck seems like the sort of thing you might do if you’d been tasked with the job of building a modern chariot for Mars – the ancient Roman God of War. The truck is the work of the Corns family, based out of Colorado where they run a 40 acre salvage yard with hundreds of vehicles and tens of thousands of parts. Each Wednesday evening the Corns family invites friends to come by and they set to work on a project vehicle – the rules for joining this weekly get together are “Love cars, bring beer, and have a sense of humour.”
The project for the radial-engined truck began years ago when Gary Corns bought the beat up old 1939 Plymouth from a regular customer. It sat for over 30 years as they worked on other projects and ruminated over what they should to with it – until one day when Corns senior found an old seaplane in a nearby airplane wrecking yard that still had its Jacobs R-755 radial engine bolted to the front.
The first order of business was to see if they could get the old radial to run, amazingly it fired up with minimal fuss in a cloud of smoke and a roar that would send a chill down the spine of Cthulhu.
The Corns team set about finding a suitable single-barrel updraft carburettor on eBay, they then fabricated the parts needed to fit it to the Jacobs R-755. Once it was fitted the ignition system could be tuned and the valve clearances adjusted to within specification – likely for the first time in decades.
The Plymouth truck’s original chassis was beyond saving so a new tube chassis was welded up, this also allowed them to extend the front of the truck to allow adequate room for the new power plant. The body was heavily modified as it was fitted to the new chassis, rivets were used extensively as a hat-tip to the aeronautical past of the 7 cylinder radial and the attention to detail is remarkable.