Cylinder Blocks

Materials Cast iron Aluminum Economical More stable than aluminum May use sleeves Aluminum Light weight Uses sleeves

Cylinder Block Features Cylinders – May be cast in or pressed in sleeves Dry sleeves – no coolant contacts the pressed in liner Wet Sleeves – Coolant runs directly on the outside of the sleeve (some form of seal needed) example: Cadillac 4.1L

Cylinder Block Features Main web – the area that supports the crankshaft Skirted blocks Non-Skirted Blocks Deck Water jacket Mounting flanges

Disassembly and Cleaning Mark all main caps for position and direction Lubricate machined surfaces after cleaning to prevent rust Remove and save all plugs (note locations) Before assembly, wash with hot soapy water

Inspection and Measurement Visually check entire block for cracks, excess casting flash, or damaged bolt holes Use additional crack detection methods Magnaflux Zyglo (dye penetrant) X-Ray Sono

Inspection and Measurement Measure cylinder bores – correct problems by boring and/or honing Size Taper Out-of-round Surface finish Scoring Scratches Washboarding (use a rigid hone to detect)

Boring and Honing Boring enlarges the cylinder to a specific diameter to correct cylinder wear problems Honing imparts the correct surface finish to the cylinder wall to ensure proper ring break-in, sealing, and wear Torque plates should be used when honing cylinders “Hot Honing” is beginning to be used to simulate the distortion caused by engine heat

Cross Hatch Angle The correct angle for cross hatch lines to intersect is approximately 30 degrees.

Cross Hatch Angle Too flat a cross hatch angle can hold excess oil which causes thicker oil films which the piston rings will ride up on or hydroplane. Excessive oil consumption will result.

Cross Hatch Angle Too steep an angle promotes oil migration down the cylinder resulting in a thin oil film which can cause ring and cylinder scuffing.

Inspection and Measurement Measure main bearing bores Saddle alignment Size Taper Out-of-round Bore finish Correct any problems by align honing or align boring This will move the crank and cam centerlines closer together and may cause timing chain to be loose

Inspection and Measurement Check camshaft bore alignment- correct by installing semi-finished bearings and align boring Precision straightedge Inspect the old bearings Deck surface – Correct problems by machining ( this will affect compression ratio and valve to piston clearance) Warpage Parallel to crank centerline

Performance Modifications De-bur block Polish and paint lifter valley (only for high rpm use) Restrict oil drainback from lifter valley to camshaft Install drainback screens Sono cylinder walls for maximum possible overbore Install splayed main caps