The 4 cylinder Iron Duke was used in a variety of GM vehicles and changed several times.The early ones have both the exhaust and intake on the same side, but the ones after 1980 or so have a cross flow head. The ones found in the S-10 are probably the best of the bunch.They are very popular in 2.5 liter racing classes in boats and midget racers.The later ones are fairly rugged units. The block and head is a slightly different design for rear or front drive applications.The front drive engines had the poor rep for cracked heads.Hi po parts are reasonably available, often listed for Pontiac rather than Chevy.The Iron duke is a short stroke design, with a 4 inch bore and a 3 inch stroke. All 4 cylinder auto engines made in the 10 years have longer strokes than the bore is wide. Generally in the 3.5 inch range. That also includes 8000 rpm Honda engines. RPM limits on longer strokes are not a design problem any more. The engines use longer strokes for better crankshaft leverage,The piston lingers longer at TDC allowing a better filling of the cylinder and the smaller piston head reduces emissions and the cylinder seal is improved.
[ 12-12-2001: Message edited by: Tony ]
