RPM Limit 7.4MPI B3

G

GL2238

Cadet
Joined
Sep 8, 2004
Messages
19
26' 2001 SeaRay Sundancer with 7.4MPI B3 tops out with best trim at about 4,000 rpm. Identical boat and two equiv Well Craft with same equipment and same pitch props turn 4,300 through 4,600. Engine is smooth and runs like a clock. Mechanic diagnostic indicates all is A-OK. Could the over rev limit be set to low? Is the limit mechanical or electronic? Bottom is clean. Any suggestions?<br /><br />Gerald
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: RPM Limit 7.4MPI B3

You need to change props to a different pitch. Comparing pitch from a Wellcraft to a searay doesn't work. Depending on loading, even 2 different 26' 2001 SeaRay Sundancer with 7.4MPI B3 could need differnt prop pitches.
 
G

GL2238

Cadet
Joined
Sep 8, 2004
Messages
19
Re: RPM Limit 7.4MPI B3

Your last sentense is interesting. The identical boat has the same equipment i.e. hot water heater and was topped off water and fuel as mine was. Seems to me a little difference could be accounted for but 400+ RPM to the Other SeaRay tells me something else is not quite right. The sister boat I was on turned just over 4,400 RPM. I would also add that to keep things even the tabs were full up/flat on our runs. Props were confirmed to be the same and neither was ever re-pitched or had cup reshaped. Tach was confirmed right on the money. <br /><br />Tnx for response.
 
T

tylerin

Commander
Joined
Jul 25, 2003
Messages
2,368
Re: RPM Limit 7.4MPI B3

I would also add that to keep things even the tabs were full up/flat on our runs.
Click to expand...
So they aren't identical. Tabs on my boat made a difference even when they were in the up position
 
G

GL2238

Cadet
Joined
Sep 8, 2004
Messages
19
Re: RPM Limit 7.4MPI B3

Agree: When a poor installation results in the tab leading edge below the bottom, when up and even by 1/4 ", loss of RPM results, but not 400 RPM? Tabs are correctly aligned with the bottom on both boats. <br /><br />I have, however, seen loses in excess of 400 RPM when 1/4" caused significant drag on the hull. <br /><br />Tnx for reply.
 
T

tylerin

Commander
Joined
Jul 25, 2003
Messages
2,368
Re: RPM Limit 7.4MPI B3

Tabs are correctly aligned with the bottom on both boats. <br />
Click to expand...
So are mine GL. Maybe one or both of the tachs are off. Possible your foam filled compartments under floor are saturated causing excess weight. I live in Ventura county myself where do you fish or boat out of?
 
Don S

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: RPM Limit 7.4MPI B3

I'm not exactly sure what you want any more. If every thing on your boat is perfect, then it should be getting the proper rpm. You cannot change the rev limiter settings because it's part of the computer. If your engine is running smooth at 4000 rpm, you are not against the rev limiter.<br />If you talk to your dealer, the may lend you a set of props to test. If that works and the rpm comes up then the case is closed and there is no reason to keep guessing what the problem should be.<br />All props are not exactly the same. Even one prop could be labled wrong, hard to say, but till you try something, it's not going to do any good to keep speculating.
 
You must log in or register to reply here.
Top