Jeep Engines - Oljeep

44 MOPAR PERFORMANCE PARTSMeasuring Bearing-to-Journal Clearance1.2.3.4.5.6.7.8.9.Wipe the journal clean of oil.Use short rubber hose sections over rod bolts duringinstallation. (For more information, refer toConnecting Rod Bolt Protectors, 'Connecting Rods'section of Chapter 4.)Lubricate the upper bearing insert and install inconnecting rod.Use piston ring compressor to install the rod and pistonassemblies with the oil squirt holes in the rods facing thecamshaft and the arrow on the piston crown pointing tothe front of the engine (Figure 2-37). Verify that the oilsquirt holes in the rods face the camshaft and that thearrows on the pistons face the front of the engine.Install the lower bearing insert in the bearing cap. Thelower insert must be dry. Place a strip of Plastigaugeacross the full width of the lower insert at the center ofbearing cap. Plastigauge must not crumble in use. Ifbrittle, obtain fresh stock.Install bearing cap and connecting rod on the journaland tighten nuts to 45 Nom (33 ft-lbs) torque. DO NOTrotate crankshaft. Plastigauge will smear, resulting ininaccurate indication.Remove the bearing cap and determine the amount ofbearing-to-journal clearance by measuring the width ofcompressed Plastigauge using the scale on thePlastigauge envelope (Figure 2- 16). The correctclearance is 0.0381 to 0.0635 mm (0.0015 to 0.0025").Note: Plastigauge should indicate the same clearanceacross the entire width of the insert. If the clearancevaries, it may be caused by either a tapered journal,bent connecting rod, or foreign material trappedbetween the insert and cap or rod.If the correct clearance is indicated, replacement of thebearing inserts is not necessary. Remove thePlastigauge from crankshaft journal and bearing insert.Proceed with installation.If bearing-to-journal clearance exceeds thespecification, install a pair of 0.0254 mm (0.001")undersize bearing inserts and measure the clearance asdescribed in the previous steps.10. The clearance measured with a pair of 0.0254 mm(0.001 ") undersize bearing inserts installed willdetermine if two 0.0254 mm (0.001") undersize insertsor another combination is needed to provide the correctclearance (see the Connecting Rod Bearing FittingChart, Figure 2-32).Example: If the initial clearance was 0.0762 mm(0.003"), 0.0254 mm (0.001") undersize inserts wouldreduce the clearance by 0.0254 mm (0.001"). Theclearance would be 0.002" and within specification. A0.0508 mm (0.002") undersize insert would reduce theinitial clearance an additional 0.0127 mm (O.000St1).The clearance would then be 0.0381 mm (0.0015").Measuring Side ClearanceSlide snug-fitting feeler gauge between the connecting rodand crankshaft journal flange. The correct clearance is 0.254to 0.482 mm (0.010 to 0.019"). Replace the connecting rodif the side clearance is not within specification.Note: Too much side clearance will cause the engine tohave a high oil demand, resulting in either low or very lowoil pressure..., . ..l- .. T -1