Crown Victoria V8-281 4.6L SFI (1998)
Measure cylinder bore diameter in two directions, A and B, as shown.
Measure cylinder bore diameter in both directions at 12.70 mm (0.50 inch) below top of cylinder block deck.
Measure cylinder bore diameter in both directions at 12.70 mm (0.50 inch) above top of the piston with the piston at its lowest point of travel in the
cylinder block bore.
Measure cylinder bore diameter 32 mm (1.25984 inch) down from head deck at 90 degrees to the piston pin centerline.
The cylinder bore taper equals the difference between measurements A at top and B at bottom of cylinder bore.
The cylinder bore out of round equals the difference between measurements A and B when measured at the center of the piston travel.
Pistons are graded prior to skirt coating. Exact clearance cannot be calculated. Clearance is determined based on bore piston dimension.
If the taper, out-of-round and piston-to-cylinder bore clearance conditions of the cylinder bore are within specified limits, new piston rings will work
well.
If installing new rings in a used cylinder that has not been refinished, remove the cylinder wall glaze using only spring-loaded Engine Cylinder Hone Set
303-S084. Remove only if there is no visible sign of cross-hatch markings on the cylinder walls. Always clean the cylinder bore thoroughly with
detergent and water solution.
1. Calculate the size of piston to be used by taking a cylinder bore check. Follow procedures described in Pistons-Fitting.
NOTE: After any refinishing operation, allow cylinder bore to cool. Make sure piston and bore are clean and dry before checking piston fit.
2. Select proper size piston to provide desired clearance. Measure piston diameter in-line with centerline of piston pin and at 90 degrees to piston
axis.
3. Make sure piston and cylinder block are at room temperature, approximately 21° C (70° F).
Pistons-Fitting
The standard-size pistons are color-coded red, blue and yellow. Oversize pistons are shown in Specifications.