Cant get engine to rev over 4100 RPM
 

Hello everyone. I have a 1996 Shabah Z 272 BR. Has a 2000 7.4 MPI with 2005 Bravo lll drive. For the past two years Replaced and upgraded everything with the help of the "Mariah Boat owners club" resources. Pulled the engine before this season and replaced everything that bolts on to the engine and some just to be proactive. Everything works great. The engine runs perfect. My compression is 150 lbs accross the board. starts right up, great hole shot, runs and steers smooth. The boat weighs 6000 lbs. dry. Add 50 gallons of gas, 1 person trimed up properly and my top speed is 37 mph at 4100 RPM. Still have 35 % throttle left. ( throttle linkage is perfect). The engine has approx. 330 horse power. The bravo lll drive has a verified 2.00:1 gear ratio and the duo propeller pitch is 22. ( propeller is in excellent condition.) I checked the timing, okay at 8 degrees tdc at 600 rpm in gear. Noticed it advance when reved slightly. Did notice the inductive timing light jumping a little at 600 RPM. Thought I could have a loose timming chain or distributor problem?? I have seen many similar boats with 24 -26 props having no problems. . I was told that I should have a 2.2:1 gear ratio. Could that possibly be the reason?? I would be very pleased if I could get the boat up to 4800 RPM with a top speed of around 45mph. Any suggestions are welcome.
Thanks, Paul
PS, will post pics one of these days...

Re: Cant get engine to rev over 4100 RPM
 

Any help on this yet? I am having a similar issue and close to the same rpm. I have a lot less HP with a 1.84 and a 21p getting 4350 and 41 mph trimmed up with 3 people and a cooler . How does the hull feel?

I started at 27 mph 3800 rpm with a 19p and it is now faster only from the hull but still not right. I am thinking the rest of mine is due to bad gas .

Re: Cant get engine to rev over 4100 RPM
 

Paul ,

Can you give us the serial number from the drive you have now?
Didi it come with a dou prop originally?
See if you can give us the engine serial number too.

Larry