Home » Jeep Engine & Fuel System » Replacement Engines » ATK Engines Replacement 4.2L I-6 Engine for 75-80 Jeep® CJ-5, CJ-6, CJ-7, Cherokee & J Series Pickup
ATK Engines Replacement 4.2L I-6 Engine is no longer available
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ATK Engines Replacement 4.2L I-6 Engine for 75-80 Jeep® CJ-5, CJ-6, CJ-7, Cherokee & J Series Pickup


ATK engines with cylinder heads are engineered & fully remanufactured, using only the highest-quality parts and precision-machined tolerances. These Engines are backed by a 3-year - Unlimited mile warranty! All of ATK's manufacturing facilities are both QS-9000 and ISO 9001 certified, making them one of few engine remanufactures in the world to do so. Every engine is tested for compression, oil pressure, oil leaks, engine noise and general operating condition before shipment. Engines are shipped by truck freight. When you're ready to return your exchange core - the process is simple with our 360-Degree Core Guarantee. Simply stated, your engine core need only be the same type as the one supplied, complete with no visible damage and be able to turn over 360 degrees. Core pickup is easy. Place it in the crate and call the pickup number provided with the bill of lading. We pay the freight back. A Quadratec representative will contact you regarding the exact year of your existing engine, along with VIN number and additional shipping details. Please provide a daytime phone number and/or email when ordering.


These motors include a full range of new parts including most of these components: balanced pistons, balanced rods, valves, valve guides & lifters, rings, wrist pins and bushings, main connecting rod and camshaft bushings, timing chain, oil pump, brass freeze plugs, as well as a premium gasket set and all oil seals.

All engine blocks are magna-fluxed, bored, precision honed and mains are line-honed. The camshaft bearings are line-bored for accurate center-to-center clearance; all blocks & cylinder heads precision surfaced; cylinder heads magna-fluxed & machined for three-angle valve seats. All crankshafts are stress-relieved, precision ground and micro polished. Camshafts are precision ground or replaced with new.

Installation Notes
Installation Difficulty:
Level 4Experts Only

1. Left Head Cast #258 / 490.
2. Block Cast #445 / 098.
3. Carburated, Gas, Overhead Valve.

Installation Time: 12-16 hours
  • Jeep CJ-7

  • 1979 Jeep CJ-7
  • 1978 Jeep CJ-7
  • 1977 Jeep CJ-7
  • 1976 Jeep CJ-7
  • Jeep CJ-5

  • 1979 Jeep CJ-5
  • 1978 Jeep CJ-5
  • 1977 Jeep CJ-5
  • 1976 Jeep CJ-5
  • 1975 Jeep CJ-5
  • Jeep CJ-6

  • 1975 Jeep CJ-6
  • Jeep J Series

  • 1979 Jeep J Series
  • 1978 Jeep J Series
  • 1977 Jeep J Series
  • 1976 Jeep J Series
  • 1975 Jeep J Series
75-79 Cherokee 75-79 J-10 1976 J-20