MAINTENANCE
SERVICE MANUAL NUMBER 25
90-861328--1 NOVEMBER 1999
Page 1B-5
Engine and Tune-Up Specifications
MCM (Sterndrive)
Model
MCM 4.3L
ALPHA /
BRAVO
MCM 4.3LH
ALPHA /
BRAVO
MCM 4.3L
EFI
ALPHA /
BRAVO
Propshaft Horsepower
(SAV1 Rating)
190
205 (190)
2
210
1
(188)2
Propshaft Kilowatts (SAV1 Rating)
142
153 (142)
2
157
1
(146)
2
Number of Cylinders
V-6
Displacement
262 cid (4.3 l)
Bore / Stroke - in. (mm)
4.0 x 3.48 (101.6 x 88.4)
Compression Ratio
9.4:1
9.4:1
Compression Pressure
Minimum 100 psi (690 kPa)
7
Idle rpm In Neutral
3
650 rpm
5
600 rpm
5
Maximum rpm (at WOT)
3
4400-4800 rpm
Oil Pressure (at 2000 rpm)
Minimum 30 psi (207 kPa)
Minimum Oil Pressure (at Idle)
Minimum 4 psi (28 kPa)
Fuel Pressure (1800 rpm)
3-7 psi (21-48 kPa)
30 psi ( kPa)
Electrical System
12 V Negative (–) Ground
Alternator Rating
55 or 65 amp
8
Minimum Battery Requirements
375 cca / 475 mca / 90 Ah
Firing Order
1-6-5-4-3-2
Spark Plug Type
AC - MR43LTS
Champion - RS12YC
NGK - BPR6EFS
Spark Plug Gap
.045 in. (1.1 mm)
Timing (at idle rpm)
4
10
°
BTDC
8
°
BTDC
Preliminary Idle Mixture
1 1/4 Turns
DNA
Thermostat
160
°
F (71
°
C)
1
Power Rated in Accordance with NMMA (National Marine Manufacturers’ Association) rating procedures.
2
Power Rated in Accordance with SAV1 rating procedures. This rating procedure is used to certify that the
engine complies with “Stage 1” Bodensee and Swiss Regulations. Horsepower differences shown result from
differences in test rpm, allowable test tolerances, and/or installation of special kit components.
3
Measured using an accurate service tachometer with engine at normal operating temperature.
4
Timing must be set using a special procedure as outlined in the appropriate section of this manual. Timing can-
not be properly set using the conventional method.
5
A special procedure must be followed to adjust idle rpm. Consult your Authorized Mercury MerCruiser Dealer
before attempting this procedure.
6
Idle speed on EFI models is not adjustable.
7
Minimum recorded compression in any one cylinder should not be less than 70 percent of the highest recorded
cylinder.
8
Serial Number Break for 65 Amp alternator: OL619083 and above.
