Finnegan's Garage

More Power and Better Fuel Economy Thanks to Tuning and Overdrive! (2019x71)

Air date: Jun 14, 2019

Square Force 1 is my 1989 GMC Sierra R30 cab and chassis square body truck that was converted for enclosed car hauling duty over 30 years ago. It's powered by a 454ci V8, which is backed by a Gearstar Performance Transmissions Level Four 4L80E tranny and a Yank billet converter. Prior to swapping the original TH400 three-speed transmission with the new four-speed, the truck averaged 5.5 mpg during a 5,300 mile coast-to-coast road trip. During this episode we'll address some tuning issues with the 454 and then road trip the truck with the new trans. After the mods the truck nearly doubled it's fuel economy; We achieved a best of 9 MPG and a worst of 6.5 MPG. This video will show you how to find Top Dead Center on a four-stroke engine, how to diagnose a malfunctioning vacuum advance distributor, and how to read the timing mark on spark plugs. Hopefully you learn something or just laugh. Thanks for watching!