Engine Rebuilding Techniques & Procedures Flashcards

When resurfacing a cylinder head, what additional check must be performed on an OHC engine before reassembly?

Answer: Verify camshaft bearing bore alignment after material removal

Removing material from an OHC head deck changes the cam-to-head geometry and can misalign camshaft bearing bores, requiring verification of bore alignment.

What is 'porting' in the context of cylinder head reconditioning?

Answer: Enlarging and reshaping intake and exhaust ports to improve airflow

Porting involves carefully enlarging, reshaping, and smoothing intake and exhaust ports to reduce flow restrictions and increase engine breathing efficiency.

Which measurement confirms that a cylinder block's main bearing bore is properly aligned from front to rear?

Answer: Line bore alignment measured with a precision bar or laser alignment tool

A precision alignment bar or laser tool checks whether all main bearing bores share a common centerline, confirming proper alignment before bearing installation.

What is the effect of installing a piston with its orientation reversed (front to rear) in a non-symmetrical piston design?

Answer: Offset pin bore and valve pockets will be misaligned, causing piston damage

Non-symmetrical pistons have offset wrist pin bores and directional valve reliefs; reversing orientation misaligns these features, potentially causing contact with valves or abnormal wear.

After a valve job, what measurement ensures that valves are not sitting too deep in the head (excessive valve sink)?

Answer: Installed valve stem height relative to a datum on the head

Measuring installed valve stem height from a reference datum on the head reveals excessive sinking of the valve into its seat, which reduces compression and may cause coil bind.

What is the primary reason for hot tanking or jet washing a block before machining operations?

Answer: To remove grease, scale, and debris so machining tools and measurements are accurate

Cleaning removes contamination that would interfere with precision measurements and damage expensive machine tools, ensuring accurate machining results.

Which factor most directly determines the correct piston-to-wall clearance specification for a given engine?

Answer: Piston material and skirt design (cast vs. forged, slipper vs. full skirt)

Piston material and skirt design dictate thermal expansion characteristics; cast pistons typically require tighter clearance than forged pistons, and skirt design affects the contact area.