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Tech Specs > Mercruiser Big V8 Engine Spec's
454 CID / 7.4L / 502 CID / 8.2L Engine Specifications
|
Unit of Measurement
In. (mm)
|
|
DISPLACEMENT
|
7.4L
|
454 MAGNUM
|
502 MAGNUM / 8.2L
|
|
Bore
|
4.25(108)
|
4.46 (113.28)
|
|
Stroke
|
4.00 (101.6)
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|
Compression Ratio
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8.0:1
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8.6:1
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8.75:1
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|
Heads
|
Cast Iron
(
Oval
Port )
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Cast Iron
(Rectangular Port)
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|
Intake Manifold
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Cast Iron
|
Aluminum With Brass Inserts-High Rise (See Note)
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|
Block
|
Cast Iron (4 Bolt Main Bearing Caps)
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|
Rods
|
Forged Steel
|
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Pistons
|
Cast Aluminum
|
Forged Aluminum
|
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Crankshaft
|
Cast Steel
|
Forged Steel
|
|
Camshaft
|
Cast Iron
|
Note: 7.4L / 454 and 5/2 Magnum MPI are equipped with a cast aluminum intake manifold with brass inserts.
CYLINDER BORE
|
ENGINE
|
7.4L
|
454 MAGNUM
|
502 MAGNUM/ 8.2L
|
|
Diameter
|
4.2500-4.2507
(107.950-107.967)
|
4.2451-4.2525
(107.826-108.013)
|
4.4655-4.4662
(113.423-113.441)
|
|
Out of Round
|
Production
|
.001 (0.025) Max
|
|
Service
|
.002 (0.05) Max
|
|
Taper
|
Production
|
Thrust Side
|
.0005 (0.0127) Max
|
|
Relief Side
|
.001 (0.0254) Max
|
|
Service
|
.001 (0.02) Over Production
|
PISTON
|
Clearance
|
Production
|
.0018-.0030
(0.0457-0.0762)
|
.0025-.0037
(0.0635-0.0939)
|
.0040-.0057
(0.1016-0.1447)
|
|
Service
|
.0018 (0.0457)
Max
|
.0075 (0.15) Max
|
.0065 (0.16) Max
|
PISTON RING
|
ENGINE
|
7.4L
|
454 MAGNUM
|
502 MAGNUM 8.2L
|
|
Compression
|
Groove
Side
Clearance
|
Production
|
Top
|
.0012-.0029
(0.044-0.081)
|
.0017-.0032
(0.044-0.081)
|
.0017-.0032
(0.044-0.081)
|
|
2nd
|
.0012-.0029
(0.044-0.081)
|
.0017-.0032
(0.044-0.081)
|
.0017-.0032
(0.044-0.081)
|
|
Service
|
High Production Limit + .010(0.02) Maximum
|
|
Gap
|
Production
|
Top
|
.010-.018
(0.25-0.46)
|
.011-.021
(0.28-0.53)
|
|
2nd
|
.016-.024
(0.41-0.61)
|
.016-.026
(0.41-0.66)
|
|
Service
|
High Limit Production + .010 (0.25) Maximum
|
|
Oil
|
Groove
Side
Clearance
|
Production
|
.0050-.0065 (0.127-0.165)
|
|
Service
|
High Limit Production + .001(0.25)
|
High Limit
Production
.005 (0.12) Max
|
|
Gap
|
Production
|
.010-.030
(0.254-0.762)
|
.020-.035
(0.508-0.889)
|
.010-.030
(0.254-0.76)
|
|
Service
|
High Limit Production + .001 (0.25)
|
High Limit
Production
.005 (0.12) Max
|
|
|
|
|
|
|
|
|
PISTON PIN
|
ENGINE
|
7.4L
|
454 MAGNUM
|
502 MAGNUM
|
|
Diameter
|
.9895-.9897
(25.132-25.1371)
|
.9895-.9898
(25.134-24.140)
|
|
Clearance In Pin
|
Production
|
.0002-.0007
(0.0050-0.0177)
|
.00025-.00035
(0.0064-0.0088)
|
|
Service
|
.001(0.025) Maximum
|
|
Fit In Rod
|
.0021-.0031
(0.0533-0.0787)
Interference
|
.0008-.0016(0.021-0.040)
Interference
|
454 CID / 7.4L / 502 CID / 8.2L Engine Specifications
|
Unit of Measurement
In. (mm)
|
CRANKSHAFT
|
ENGINE
|
7.4L
|
502 MAGNUM / 8.2L/454 MAGNUM
|
|
Main
Journal
|
Diameter
|
No. 1,2,3,4,5
|
2.7482-2.7489 (69.8042-69.8220)
|
|
Taper
|
Production
|
.0004 (0.010) Max
|
.0002 (0.005) Max
|
|
Service
|
.001 (0.02) Maximum
|
|
Out of Round
|
Production
|
.0002 (0.005) Maximum
|
|
Service
|
.001 (0.005) Maximum
|
|
Main Bearing
Clearance
|
Production
|
No. 1,2,3,4
|
.0017-.0030
(0.043-0.076)
|
.0017-.0030
(0.043-0.076)
|
|
No. 5
|
.0025-.0038 (0.063-0.096)
|
|
Service
|
No. 1
|
.001-.003
(0.03-0.07)
|
.0010-.0015
(0.0254-0.0381)
|
|
No. 2,3,4
|
.001-.003
(0.03-0.07)
|
.0010-.0025
(0.0254-0.0635)
|
|
No. 5
|
.0025-.0040 (.0635-.1016)
|
|
Crankshaft End Play
|
.005-.0011
(0.127-0.279)
|
.006-.0010
(0.15-0.2)
|
|
Connection
Rod Journal
|
Diameter
|
2.1990-2.1996 (55.8546-55.8698)
|
|
Taper
|
Production
|
.0005 (0.0127) Maximum
|
|
Service
|
.001 (0.0254) Maximum
|
|
Out of Round
|
Production
|
.0005 (0.0127) Maximum
|
|
Service
|
.001 (0.0254) Maximum
|
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Rod Bearing Clearance
|
Production
|
.0011-.0029 (0.028-0.074)
|
|
Service
|
.001 (0.0254) Max
|
.003 (0.076) Max
|
|
Rod Side Clearance
|
.013-.023 (0.35-0.58)
|
|
Crankshaft Runout @ No. 3 main Bearing
|
.0015 (0.038) Max
|
.0035 (0.088) Max
|
454 CID / 7.4L / 502 CID / 8.2L Engine Specifications
|
Unit of Measurement
In. (mm)
|
VALVE SYSTEM
|
ENGINE MODEL
|
7.4L
|
454 MAGNUM
|
502 MAGNUM
|
|
Lifter
|
Hydraulic
|
|
Rocker Arm Ratio
|
1.70 to 1
|
|
Face Angle (Intake & Exhaust)
|
45°
|
|
Seat Angle (Intake & Exhaust)
|
46°
|
|
Seat Runout (Intake & Exhaust)
|
.002 (0.05) Maximum
|
|
Seat Width
|
Intake
|
.0300-.0600 in.
(0.7620-1.5240 mm)
|
.03125-.0625 in.
(0.79-1.58 mm)
|
|
Exhaust
|
.0600-.0950 in.
(1.5240-2.4130 mm)
|
.0625-.09375 in.
(1.58-2.38 mm)
|
|
Stem
Clearance
|
Production
|
Intake
|
.0010-.0029
(0.0254-0.737)
|
.0010-.0027
(0.025-0.069)
|
|
Exhaust
|
.0012-.0031
(0.0300-0.0787)
|
.0010-.0027
(0.025-0.069)
|
|
Service
|
Intake
|
.001 (0.02)
|
.003(0.07)
|
.0037 (0.09)
|
|
Exhaust
|
.002 (0.05)
|
.004 (0.10)
|
.0049 (0.12)
|
|
Stem Diameter
|
Intake
|
.372 (9.45)
|
|
Exhaust
|
.372 (9.45)
|
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Valve Margin (Intake and Exhaust)
|
.0312 (0.79)
|
|
Valve Lash (Intake and Exhaust)
|
Fixed Lash
|
454 CID / 7.4L / 502 CID / 8.2L Engine Specifications
|
Unit of Measurement
In. (mm)
|
VALVE SPRING
|
ENGINE MODEL
|
7.4L
|
454 MAGNUM/
502 MAGNUM
|
|
Valve Spring
(Note 1)
(Note 2)
|
Free Length
|
2.12 (53.9)
|
2.15 (54.6)
|
|
Pressure
|
Closed at
1.88 in. (47.8 mm)
|
Does Not
Apply
|
110 Lbs.
(489 N)
|
|
Closed at
1.838 in. (46.7 mm)
|
71-79 Lbs.
(316-351 N)
|
Does Not
Apply
|
|
Open at
1.34 in. (35.1 mm)
|
Does Not
Apply
|
316 Lbs.
(1406 N)
|
|
Open at
1.347 in. (34.120 mm)
|
238-262 Lbs.
(1059-1165 N)
|
Does Not Apply
|
|
Installed Height
|
1.838 (46.7)
|
1.88 (47.7)
|
|
Damper or Damper
Shield
|
Free Length
|
Does Not
Apply
|
1.86 (47.2)
|
|
Approximate Number of Coils
|
4
|
|
Damper or Damper
Shield
|
Valve Spring Fit in Damper Shield
|
.42-.094 (1.07-2.38)
Interference
|
Does Not
Apply
|
Note 1: 454/502/8.2L Models Only-Test spring pressure with inner and outer spring assembled.
Note 2: 7.4L Models Only Test spring pressure with damper shield installed.
454 CID / 7.4L / 502 CID / 8.2L Engine Specifications
|
Unit of Measurement
In. (mm)
|
ROLLER TAPPET CAMSHAFT
|
ENGINE MODEL
|
7.4L
|
454 MAGNUM
502 MAGNUM
8.2L
|
|
Lobe Lift + .020 (0.051)
|
Exhaust
|
.284 (7.214)
|
.342 (8.687)
|
|
Intake
|
.282 (7.163)
|
.342 (8.687)
|
|
Duration at .050 In. (1.27 mm)
Cam Lift
|
Exhaust
|
209°
|
227°
|
|
Intake
|
209°
|
211°
|
|
Journal Diameter
|
1.94282-1.9492 (49.485-49.509)
|
|
Journal Out Of Round
|
.001 (0.025) Maximum
|
|
Camshaft Runout
|
.002 (0.051) Maximum
|
|
Timing Chain Deflection
|
.375 (9.5) from taut position [total .75 (19)]
|
FLYWHEEL
|
Runout
|
.008 (0.203) Maximum
|
CYLINDER HEAD
|
Gasket Surface Flatness
|
.004 (0.1016)
Overall Maximum
.003 (0.076) within a
6 in. (152 mm) Span
|
.007 (0.178)
Overall Maximum
.003 (0.076) within a
6 in. (152 mm) Span
|
