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All 1978-1990 Iron Duke engines used a micartacamshaft gear that meshed directly with a steel gear on the crankshaft. Over the years, the Tech IV engine has proved to be a reliable workhorse for owners when not pushed to its limits. The Tech IV uses the same bellhousing pattern as the 2.8 L 60-Degree V6. The most powerful variant of the Tech IV raised the rev limit to 5500 rpm, and achieved 110 hp (82 kW). Further improvements in later years included new pistons, rods, crankshaft, and an in-pan oiling system. Up to this point, the engine incorporated a 'dogbone' upper front engine mount secured to the cowling of the vehicle's hood latch, aiding in controlling the vibration. In 1988, a balance shaft was added to smooth engine vibrations. This revision to the engine increased power to 98 hp (73 kW). Several significant changes were made in 1987, which included: an improved cylinder head, intake manifold and throttle-body fuel injection module, a more-modern serpentine belt with an automatic spring-loaded tensioner for the accessories, and a Distributorless Ignition System (DIS). Other additions for 1985 included roller lifters, improved bearings, and a new crankshaft.
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This was replaced by a swirl-port head with 9.0:1 (instead of 8.25:1) compression ratio in 1984 for a 2 hp (1.5 kW) gain. 1980â∱985 Buick Skylark, Chevrolet Citation.1980â∱984 Oldsmobile Omega, Pontiac Phoenix.1978â∱980 Chevrolet Monza, Oldsmobile Starfire.(The engines sold in AMCs continued to use the Chevrolet V8 bellhousing pattern.) AMC used the Iron Duke as a base engine in their cars until it was replaced with a 150 cu in (2.5 L) four-cylinder of their own design in 1984.ġ23 lbâ ft (167 Nâ m) 2800 rpm : 40ġ34 lbâ ft (182 Nâ m) 2400 rpm : 47 GM also began selling the engine to AMC, for use in their 1980 model Spirit, Concord and Eagle, and (as the Hurricane) in base-model Jeep CJs.