* Valve Train Differences: The 1986 JS engine utilizes a hydraulic lifter system, while the 1983 KE and WR engines use solid lifters. This fundamental difference in valve actuation means the heads are not interchangeable.
* Head Design: The head designs are not compatible. The JS head is specifically designed for hydraulic lifters, including the camshaft profile, rocker arm geometry, and valve stem clearances.
* Valve Stem Seal Compatibility: The JS engine uses different valve stem seals that are incompatible with the solid lifter heads.
* Intake and Exhaust Manifold Compatibility: The manifold mounting points and configurations might differ between the JS and KE/WR heads, making them incompatible.
Potential Workarounds (Not Recommended):
While directly swapping the head isn't possible, some modifications could be attempted, but they are highly discouraged due to significant complexities and potential reliability issues:
* Modify the JS Head: You could potentially modify the JS head to accept solid lifters, but this is a complex and risky undertaking, requiring machining and potentially compromising the head's integrity.
* Custom Cam: You could try to find a custom camshaft designed for solid lifters and tailored for the JS head. This would still require significant modifications to the valve train and would likely result in poor performance and reduced reliability.
Conclusion:
Attempting to fit a solid lifter head onto a hydraulic lifter engine is not a practical or reliable solution. Stick to using compatible parts for your 1986 JS engine to ensure optimal performance and longevity.
