From a distant galaxy of single overhead cam engines comes the Mitsubishi Astron series. The mighty Astron began life in 1972, and is still ticking away under the hoods of everything from Mitsubishi Starions to the panoply of Chrysler K-Car variants. In the beginning, the Flying Sikh himself pummeled an Astron equipped original Lancer to numerous rally victories. Patented silent shaft technology canceled out harmonics as the engine grew in displacement from 1.8 to 2.6 liters of four pot fury. The last production car to pack the Astron was either the the 1991 Pajero or the 1990 Starion, but only if not counting the diesel version of the Astron - which motored on with turbo until 1993 amid Galants. 21 years of Astron! In sourcing a new cylinder head sans jet valves for one of the two 2.6L G54B turbo variants of the Astron in our garage we learned that the 'ol G54B aspirated on propane with propane accessories serves in many forklifts to this day. The odd marriage of Mopar, Mitsubishi, and K-Car station wagons also led to some innovative badging - as seen in the bonus pic after the jump. [Mitsubishi Astron]
The only chain with an adjustment on this engine was the silent shaft chain, which directly drove one balance shaft and the oil pump. The other balance shaft was driven in the opposite direction by the oil pump. The one and only timing chain had no adjustment, a hydraulic tensioner kept it snug.
One balance shaft spun at twice crankshaft speed in the same rotation as the crankshaft while the other balance shaft's rotation was in reverse of the crank's rotation at 1/2 crankshaft RPM. As soon as the hydraulic tensioner let the heavy timing chain go slack for just a second, a guide bolt that did double duty at the end of two different chain guides would break. That's all folks!