Is the Max rev the Max

[metcalfej]

I have a 1977 700Merc EL. I am wanting to know if I can increase the maximum throttle without problems. I have the riight prop for the boat with a nice smooth take off and the trim is also optimum, the only problem is that it tops out at 4000rpm when it is rated to top out at 5000-5500, when I was moving the trim about it didn't seem to make much of a difference to the top rev's, could this still be a wrong prop or is the throttle stop wrong?? Is it doing damage to the engine running at 4000

Thanks for your guidance

 

[JB]

Re: Is the Max rev the Max

You may have the wrong prop. Yes, you are lugging the engine if it is making full power and won't go to 5500 at WOT with a light load. That is very bad for the engine.

First, make sure it is making full power, then go to the Prop Forum for advice on getting the correct prop.

Good luck.

 

[Texasmark]

Re: Is the Max rev the Max

You could pull the cowl and look and see where the throttle linkage in the engine is positioned when the remote is at WOT.

Then remove the remote cable from the throttle linkage at the engine and manually push the engines throttle control as far back as it will go. If in the same position as before, I'd put my money in the wrong setup or prop pitch. There are tweaks on the linkage but for the other end of the operating rpm band.

Mark

 

[metcalfej]

Re: Is the Max rev the Max

The throttle does achieve the maximum travel on the throttle lever, however there is a throttle stop screw which isn't fully back, that could be screwed out a little further to achieve a higher throttle, I don't know whether this is factory set and therefore shouldn't be moved?

 

[cobra 3.0]

Re: Is the Max rev the Max

I doubt that the little screw will get you the needed 1500 rpm. You may have a spun hub in the prop too(the rubber insert slips at higher rpm). What's the pitch on the prop now?(It's usually written on the outside or on the inside of the hub.)

 

[Silvertip]

Re: Is the Max rev the Max

Remove the air box and check the throttle plate position at full throttle setting. If the plates are perfectly horizontal you have full throttle. No more adjusting will help. You either have an engine problem, engine set-up problem, boat problem, or prop problem.

 

[Texasmark]

Re: Is the Max rev the Max

Cobra man, you're going the wrong way. He's low in rpm's not high. 8)

Mark