4.3L Engine Mechanical Specifications - Performance Product Technologies

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You are Here: Tech Specs > Mercruiser 4.3L Engine Spec's

262 cid / 4.3L Gen + Engine Specifications

Unit of Measurement

In. (mm)

Displacement	262 CID (4.3 Liter)
Bore	4.00 (101.6)
Stroke	3.48 (88.39)
Compression Ratio	9.3:1
Heads	Cast Iron
Intake Manifold	Cast Iron
Block	Cast Iron (2 Bolt Main Bearing Caps)
Rods	Forges Steel
Pistons	Cast Aluminum
Crankshaft	Cast Iron
Camshaft	Steel

CYLINDER BORE

Diameter			4.0007-4.0017(101.618-101.643)
Out of Round		Production	.001 (0.025) Maximum
		Service	.002 (0.051) Maximum
Taper	Production	Thrust Side	.0005 (0.012) Maximum
		Relief Side	.001 (0.025) Maximum
	Service		.001 (0.025) Maximum

PISTON CLEARANCE

Production	.0007-.002 (0.017-0.05)
Service	.0024 (.001)

PISTON RING: COMPRESSION (MEASURE IN CYLINDER BORE)

Groove Clearance	Production	Top	.02-.06 (0.51-1.52)
		2^nd	.04-.08 (1.02-2.03)
	Service		.0042 (0.107) Maximum
Gap		Top	.010-.016 (0.25-0.40)
		2^nd	.018-.026 (.046-.066) Maximum
	Service		.06-.035 (1.524-0.88) Maximum

PISTON RING: OIL

Groove Clearance	Production	.002-.007 (0.51-0.20)
Groove Clearance	Service	.02-.08 (0.51-2.032)
Gap	Production	.015-.050 (0.38-1.27)
Gap	Service Limit	.009-.065 (0.23-1.65)

PISTON PIN

Diameter		.9267-.9271 (23.545-23.548)
Clearance	Production	.0002-.0007 (0.005-0.0178)
	Service Limit	.001 (0.025) Maximum
Fit in Rod		.0008-.0016 (0.021-0.040) Interference

CRANKSHAFT

Main Journal	Diameter	No. 1	2.4488-2.4495 (62.199-62.217)
		No. 2, 3	2.4485-2.4494 (62.191-62.215)
		No. 4	2.4479-2.4489 (62.179-62.203)
	Taper	Production	.0003 (0.007) Maximum
	Taper	Service	.001 (0.025) Maximum
	Out of Round	Production	.0002 (0.005) Maximum
	Out of Round	Service	.001 (0.025) Maximum
Main Bearing Clearance	Production	No. 1	.0008-.0020 (0.020-0.051)
	Production	No. 2, 3, 4	.001-.025 (0.025-0.635)
	Service	No. 1, 2, 3, 4	.001-.002 (0.030-0.051)
Crankshaft End Play			.002-.008 (0.05-0.20)
Connecting Rod Journal	Diameter		2.2487-2.2497 (57.117-57.142)
	Taper	Production	.0003 (0.007) Maximum
	Taper	Service	.001 (0.025) Maximum
	Out of Round	Production	.0002 (0.0051) Maximum
	Out of Round	Service	.001 (0.025) Maximum
Rod Bearing Clearance		Production	.0013-.0035 (0.033-0.088)
Rod Bearing Clearance		Service	.001-.003 (0.025-0.076)
Rod Side Clearance			.006-.017 (0.15-0.43)
Crankshaft Runout			.001 (0.025) Maximum

VALVE SYSTEM

Lifter			Hydraulic Roller
Rocker Arm Ratio			1.50 to 1
Valve Lift		Intake	.414 (10.52)
		Exhaust	.428 (10.87)
Valve Lash (Intake & Exhaust)			Net Lash No Adjustment
Face Angle (Intake & Exhaust)			45°
Seat Angle (Intake & Exhaust)			46°
Seat Runout (Intake & Exhaust)			.002 (0.05) Maximum
Seat Width		Intake	.035-.060 (0.89-1.52)
		Exhaust	.062-.093 (1.58-2.38)
Stem Clearance	Production	Intake	.0010-.0027 (0.025-0.069)
		Exhaust
	Service	Intake	.001 (0.025) Maximum
		Exhaust	.002 (0.51) Maximum
Stem Diameter		Intake	.34-.3407 (8.636-8.653)
		Exhaust
Valve Margin (Intake & Exhaust)			.031 (0.79)

VALVE SPRING

Valve Spring	Free Length		2.03 (51.6)
	Pressure	Valve Closed	76-84 Lb. (338-374 N) at 1.7 in (43.16 mm)
		Valve Open	187-203 Lb. (832-903 N) at 1.27 in (32.25 mm)
	Installed Height		1.690-1.710 in (42.93-43.43 mm)

CAMSHAFT AND DRIVE

Lobe Lift + .002(0.051)	Intake	.286-.290 (7.26-7.36)
	Exhaust	.292-.296 (7.42-7.52)
Journal Diameter		1.8682-1.8692 (47.452-47.478)
Journal Out of Round		.001 (0.025) Maximum
Camshaft Runout		.002 (0.051) Maximum
Camshaft End Play		.001-.009 (0.0254-0.2286)
Timing Chain Deflection		.375 (9.5) from taut position [total .75 (19)]

FLYWHEEL

Runout

.008 (0.203) Maximum

CYLINDER HEAD

Gasket Surface Flatness

.010 (0.254) Overall Maximum

BALANCE SHAFT

Front Bearing Journal	2.1648-2.1654 (54.985-55.001)
Rear Bearing Journal	1.4994-1.500 (38.084-38.100)
Rear Bearing Journal Clearance	.001-.0036 (.025-.091)

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