Jeep Engines - Oljeep

-7-766 MOPAR PERFORMANCE PARTSValve Stem-to-Guide Clearance MeasurementValve stem-to-guide clearance may be measured by eitherof the following two methods.1. Preferred MethodRemove the valve from the head.Clean the valve stem guide bore with solvent andbristle brush.Insert a telescoping gauge into the valve stem guidebore approximately 9.525 mm (3/8") from the valvespring side of the head with contacts crosswise tothe cylinder head (Figure 2-67). Remove andmeasure telescoping gauge with a micrometer.Repeat the measurement with contacts lengthwiseto cylinder head.Compare the crosswise to lengthwisemeasurements to determine out-of-roundness. Ifthe measurements differ by more than 0.0635 mm(0.0025"), ream the guide bore to accommodatean oversize valve stem.Compare the measured valve guide bore diameterwith specifications (7.95-7.97 mm or 0.3 13-0.314"). If the measurement differs fromspecification by more than 0.076 mm (0.003"),ream the guide bore to accommodate an oversizevalve stem.Note: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.2. Alternate MethodVALVE SEATSUse a dial indicator to measure the lateralmovement of the valve stem (stem-to-guideclearance). This must be done with the valveinstalled in its guide and just off the valve seat(Figure 2-68).Correct clearance is 0.025-0.0762 mm (0.001-0.003"). If indicated movement exceeds thespecification, ream the valve guide toaccommodate an oversize valve stem.Note: Valve seats must be reground after reamingthe valve guides to ensure that the valve seat isconcentric to the valve guide.Figure 2 - 68ICYLINDERHEADFigure 2 - 67VALVE. STEMGUIDEJEW-92With cast iron cylinder heads, all the valve seats aremachined into the head material. (Aluminum heads usevalve seat inserts.) One of the most important items in ahigh output engine is the valve job.Valve Seat Refacing1. Install a pilot of the correct size in the valve guide boreand reface the valve seat to the specified angle with agood dressing stone (Figure 2-69). Remove onlyenough metal to provide a smooth finish.2.3.Use tapered stones to obtain the specified seat widthswhen required.Control valve seat run-out (Figure 2-70) to a maximumof 0.0635 mm (0.0025").