Camshaft; Measuring Lobe Lift; Removal - Mercury MerCruiser MCM 454 Mag MPI Service Manual

454 CID (7.4L) / 502 CID (8.2L)

Camshaft

Measuring Lobe Lift

NOTE: Procedure is similar to checking valve timing. If improper valve operation is indi-
cated, measure lift of each push rod in consecutive order and record readings.
1. Remove valve mechanism as outlined.
2. Adapt dial indicator to cylinder head by temporarily installing suitable stud in bolt hole.
Position indicator with ball socket adaptor tool, from Lift Indicator Tool Kit, on push rod.
Be sure that push rod is in lifter socket.
3. Rotate torsional damper slowly in direction of rotation until lifter is on heel of cam lobe.
At this point, push rod will be in its lowest position.
4. Set dial indicator on zero, then rotate torsional damper slowly (or attach an auxiliary
starter switch and "bump" engine over) until push rod is in fully raised position.
5. Compare total lift, recorded from dial indicator, with "Specifications."
6. Continue to rotate engine until indicator reads zero. This will be a check on accuracy of
original indicator reading.
7. If camshaft readings for all lobes are within specifications, remove dial indicator assem-
bly and hardware.
8. Install and torque valve mechanism to "Specifications."

Removal

1. Remove valve lifters as outlined.
2. Remove crankcase front cover as outlined.
3. Remove camshaft as follows:
a. Remove timing chain and sprocket or timing gears as outlined.
b. Install two 5/16-18 x 5 in. bolts in camshaft bolt holes and carefully remove camshaft
Index
Page 3A-78
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a - Lift Indicator Tool Kit (J-8520)
as shown.
SERVICE MANUAL NUMBER 23
a
90-861326--1 MARCH 1999
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72549