Jeep Engines - Oljeep

T - T i l4.0L POWER TECH IN-LINE 6 (CONNECTING RODS) 151CONNECTING ROD BEARINGSFor racing purposes there are two special connecting rodbearings materials used: Babbit and Tri-Metal. In general,Tri-Metal is preferred for oval track racing, Babbit for dragracing.InstallationFit all connecting rods on one cylinder bank untilcompleted. DO NOT alternate from one bank to another,because when the rods are assembled to the pistonscorrectly, they are not interchangeable from one bank toanother.The bearing caps are not interchangeable and should bemarked at removal to ensure correct assembly.Each bearing cap has a small V-groove across the partingface. When installing the lower bearing shell, make certainthat the V-groove in the shell is in line with the V-groovein the cap. This provides lubrication of the cylinder wall inthe opposite bank.The bearing shells must be installed so that the tangs are inthe machined grooves in the rods and caps.Limits of taper or out-of-round on any crankshaft journalsshould be held to 0.0254 mm (0.001"). Bearings areavailable in 0.025 mm (0.001"), 0.051 mm (0.002"), 0.076mm (0.003"), 0.254 mm (0.010") and 0.305 mm (0.012")undersize. (Contact your local Chrysler-Plymouth-Dodge-Jeep dealer for ordering information.)Note: Install connecting rod bearings in matched pairs. DONOT use a new bearing half with an old bearing half. DONOT file the rods or bearing caps.Measuring Connecting Rod Bearing Clearance1.2.3.4.5.Wipe the journal clean of oil.Use short rubber hose sections over rod bolts duringinstallation.Lubricate the upper bearing insert and install inconnecting rod.Use a 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.6. 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.7.8.Remove the bearing cap and determine the amount ofbearing-to-journal clearance by measuring the width ofcompressed Plastigauge by using the scale on thePlastigauge envelope (Figure 2-16). The correctclearance is 0.025 to 0.076 mm (0,001 to 0.003").Plastigauge should indicate the same clearance acrossthe entire width of the insert. If the clearance varies, itmay be caused by either a tapered journal, bentconnecting rod, or foreign material trapped betweenthe 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.9. If bearing-to-journal clearance exceeds thespecification, install a pair of 0.0254 mm (0.001")undersize bearing inserts. All the odd size inserts mustbe on the bottom. Service replacement bearing insertsizes are stamped on the backs of the inserts. Measurethe clearance as described in the previous steps.10. The clearance measured with a pair of 0.0254 mm(0.00 1 ") undersize bearing inserts installed willdetermine if two 0.0254 mm (0.001") undersize insertsor another combination is needed to provide the correctclearance. (Refer to Connecting Rod Bearing FittingChart [Figure 4- 151 .)Example: If the initial clearance was 0.0762 mm(0.003"), 0.025 mm (0.001") undersize inserts wouldreduce the clearance by 0.025 mm (0.OOlll). Theclearance would be 0.002" and within specification. A0.051 mm (0.002") undersize insert would reduce theinitial clearance an additional 0.013 mm (0.0005").The clearance would then be 0.038 mm (0.0015").11. Repeat the Plastigauge measurement to verify yourbearing selection prior to final assembly.12. Once you have selected the proper insert, install theinsert and cap. Tighten the connecting rod bolts to 45N*m (33 ft-lbs) torque.