AERA Cylinder Head Rebuilding & Valve Train

Question 1

When measuring valve guide inside diameter, what is the maximum acceptable clearance between the valve stem and guide for a typical intake valve on a passenger car engine?

Accepted Answer

0.0010–0.0027 in (0.025–0.069 mm)

Answer

0.0050–0.0080 in (0.127–0.203 mm)

Answer

0.0030–0.0045 in (0.076–0.114 mm)

Answer

0.0001–0.0005 in (0.003–0.013 mm)

Question 2

What is the primary purpose of cutting a three-angle valve seat?

Accepted Answer

To narrow the contact band for better sealing and heat transfer

Answer

To widen the contact band for increased flow area

Answer

To increase the valve face-to-seat interference fit

Answer

To reduce the need for valve lapping compound

Question 3

When checking cylinder head flatness with a precision straightedge and feeler gauge, what is a commonly accepted maximum warpage limit for an aluminum head?

Accepted Answer

0.002 in (0.05 mm) per 6 inches

Answer

0.010 in (0.25 mm) per 6 inches

Answer

0.025 in (0.64 mm) per 6 inches

Answer

0.001 in (0.025 mm) per 6 inches

Question 4

Valve spring installed height directly affects which critical valve train parameter?

Accepted Answer

Spring seat pressure and open pressure

Answer

Rocker arm geometry and pushrod angle

Answer

Valve face-to-seat contact width

Answer

Lifter preload on hydraulic systems

Question 5

What condition is indicated when the valve margin (the edge between the valve face and the top of the valve head) is less than the manufacturer's minimum specification after valve face grinding?

Accepted Answer

The valve must be replaced to prevent burning or breakage

Answer

The valve can be reused if the seat angle is corrected

Answer

Additional lapping will restore adequate margin thickness

Answer

The valve stem seal must be upgraded to compensate

Question 6

Which method is used to verify that rocker arm geometry is correct after a cylinder head has been resurfaced?

Accepted Answer

Check that the rocker arm tip contacts the center of the valve stem tip at mid-lift

Answer

Measure the rocker arm ratio with a dial indicator at the valve tip and pushrod cup

Answer

Verify that the pushrod is parallel to the cylinder bore centerline

Answer

Confirm that all rocker arms are torqued to the same specification

Question 7

When installing new valve stem seals, what is the correct procedure to prevent damage during installation on an assembled head?

Accepted Answer

Use a proper seal driver and lightly lubricate the seal lip; protect the seal over the valve stem keeper grooves with a sleeve or tape

Answer

Press the seal on dry to avoid contaminating the sealing surface with lubricants

Answer

Heat the seal with a heat gun before installation to soften the rubber

Answer

Install the seal after the valve spring and retainer are in place to hold it in position