Mercruiser 230 V8 3900rpms WOT

mattymuch

Cadet
Joined
Jul 21, 2016
Messages
15
I have a 1985 Four Winns Cuddy 195 horizon Mercruiser 230. Owned the boat the past 3 years and has ran very well. It's my first boat and I've tried to gain some knowledge over the few years. I have a small idea on what to be looking for. When I purchased the boat the timing was off. I had a buddy time the engine in the water under load by turning the distributer. I know now that this was a rigged way and it should have been done with a light. At that time also changed plugs, wires, and coil. Today the boat still runs very well. I've never checked to see if the choke worked, basically choked it myself, hit the neutral switch pump throttle a couple times and pull it back close to neutral and fires right up every time. let it idle for about 45 seconds with slight throttle then click it back into locked neutral and its good. Boat would do about 40mph but I really never paid attention to my RPMS till now. Usually go to a small lake now and rarely sees WOT long periods of time. I did a river run 2 years ago and was full throttle for a while and seem to go just fine.

Now I just had a new Outdrive installed Brand New SEI Unit. Same ratio as previous drive 1.47/1.50- prop 14.5x19. After my break in and learning more about props and how boats should be running I noticed my RPM's at 3900 WOT 2 people in the boat. My speedometer pickup broke off while in storage, the mph seems to be no different. I've talked with a Few marina's and all said that's too low. I'm going to have boat timed to proper specs, could it be just the prop? Its a pretty heavy boat IMO. Should I Do a compression test as well? would like some opinions on Where to go from here. Thank You.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
51,720
there are stickies at the top of the forums on low WOT. first place I would look is the throttle not opening all the way.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,348
Ayuh,.... Welcome Aboard,.... 3900 rpms is way to low, ya oughta be at or very near 4800 rpms at Wot,.....

If the hull is clean, 'n the motor runnin' right, yer lookin' at probably a 15" pitch prop,....

Probably shoulda gone with the 1.65:1 drive for a big heavy hull,....
 

mattymuch

Cadet
Joined
Jul 21, 2016
Messages
15
did a compression test today and everything was good. looks like my engine still has some life
 

wahlejim

Master Chief Petty Officer
Joined
Jul 23, 2015
Messages
884
If you have no speedo and didnt gps the speed, it is tough to say for sure what is going on. You are also relying on the dash gauge, often inaccurate. Before you put any money into parts or tearing things down, use a shop tach to get an accurate reading. Then go from there. It sounds like you are just shooting from the hip right now and a lot of guessing going on. Get accurate readings.
 
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