MerCruiser 350 Magnum EFI GEN+ Alfa One, Operation And Maintenance Manual

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14
IMPORTANT: The engines covered in this manual are equipped
with an RPM rev-limiter that is set to an upper (or limited) RPM
amount. This limit is slightly above the normal operating range
of the engine and is designed to help prevent damage from ex-
cessive engine RPM. Once the RPM drop into the recommended
operating RPM range normal engine operation resumes.
Select a propeller that will allow the engine power package to operate
at or near the top end of the recommended wide-open-throttle oper-
ating RPM range with a normal load. High RPM, caused by an exces-
sive trim angle, should not be used in determining correct propeller
selection.
If full throttle operation is below the recommended range, the propel-
ler must be changed to prevent loss of performance and possible en-
gine damage. On the other hand, operating an engine above the rec-
ommended operating RPM range will cause higher than normal wear
and/or damage. Generally, there is a 200-300 RPM change between
propeller pitches.
After initial propeller selection, the following common problems may
require that the propeller be changed to a lower pitch:
•
Warmer weather and greater humidity cause an RPM loss.
•
Operating in a higher elevation causes an RPM loss.
•
Operating with a damaged propeller or dirty boat bottom causes
an RPM loss.
•
Operating with increased load (additional passengers, pulling ski-
ers, etc.)
For better acceleration, such as is needed for water skiing, use the
next lower pitch propeller. However, do not operate at full throttle
when using the lower pitch propeller but not pulling skiers.