Originally Posted by MobjackB32
I just bought a 1981 Bristol 32 with a Universal 5424 that has 1150 hours. Bringing her home (30 hours) I noticed she hit cruising speed 5-6 mph at 1400-1500 rpm. I had heard that crusing rpm should be over 2000 on this engine. Is there any harm in having the crusing rpm between 1400 and 1500? Will it lug the engine or cause undo wear, overheating, etc? She has run this way for almost 30 years it would appear.
2800 is max rated RPM for the 5424. You'll want to get a photo tach to confirm your actual RPM though.
You should ideally be able to hit max rated RPM at max throttle with a clean bottom and prop in smooth current free water. 1500 is quite low for cruise RPM. You should be turning 2200-2250 for your cruise RPM..
Universal & Westebeke are very picky on proper RPM. In the spec sheet for all their new engines they will have a statement like the one below.
From the M-25 XPB Spec Sheet:
"Universal recommends a propeller that will allow the engine to turn 3000 RPM underway at full throttle"