normal crusing rpm's 350 mercruiser?

[lime4x4]

I have a 27 foot searay which weighs around 7000lbs single mercruiser engine/sterndrive.I basically have to keep the rpms between 3800 to 4000 to stay on plane. Engine was rebuilt last year along with a complete tuneup. Is that rpm range for long period of time going to hurt anything?

 

[Bondo]

Re: normal crusing rpm's 350 mercruiser?

Ayuh,.....

It'll probably run like that for a Good Long Time,.....
But,....
If it were Me,.....
I'd be lookin' at some Oversized Trim tabs,...
More planing surface might help you get your crusing rpms down to the 3200/ 3500 range......

 

[arks]

Re: normal crusing rpm's 350 mercruiser?

A newly rebuilt engine should NOT run at a constant RPM for extended periods. Vary the engine speed every few minutes.

3800 RPM's to stay on plane??? You need to check the prop and/or invest in tabs. In my experience the Sea Ray 268 needs a healthy dose of throttle to get up on plane, but once there it should maintain plane at 2800-3000.

 

[lime4x4]

Re: normal crusing rpm's 350 mercruiser?

engine was rebuilt and broken in last year.Boat currently has 12x12 bennett trim tabs which seems to be standard on all boats in the size range.I'm looking at getting a set of 30x9 tabs. that hopefully will allow less rpm's to maintain plane. It's a heavy *** boat for a single engine.

 

[Bondo]

Re: normal crusing rpm's 350 mercruiser?

Hmmmmm,........ How about a 4 blade or Cleaver prop,..??

Something with more Stern Lift,..??

 

[lime4x4]

Re: normal crusing rpm's 350 mercruiser?

after trying many many props the best one seems to be a 15.25x15 any info on the cleaver prop and which size 4 blade?

 

[billder62]

Re: normal crusing rpm's 350 mercruiser?

I run a four blade 15x16 on my 250 sun dancer , what a difference , up and on plane in no time , and cruising at about 3000 -3200 rpm