What did the mechanic do???

[Solittle]

A while back we went to the Fla. Keys for a few days. The boat (23' CC, 1988 twin OMC V4 Sea Drives) ran great except both motors would frequently die when put in neutral. The motors had plenty of power and ran 32-34 mph (GPS) at 43-4500 rpm. When we got back I took it to a mechanic to have him adjust the idle as I had a full plate with other stuff.<br /><br />The other day we went out and it seemed to idle OK but power and performance were terrible. It took forever to get on a plane, power seems way off and now I get to only 29-30 mph at 50-5200 rpm. I checked compression yesterday and all 8 cylinders were 115-118 lbs. All plugs looked OK.<br /><br />What could the mechanic have done to screw up the performance that I now need to undo?

 

[Dhadley]

Re: What did the mechanic do???

Something doesnt sound right here. You went 32 mph at 4500 rpm (which is way low) and now you turn more rpm (5200 - better but not best) and go slower (30 mph)?<br /><br />If he switched props to gain top rpm you should gain acceleration also but lose on top speed. If he retarted the timing, which would explain the slow acceleration, you would most likely not gain 700 rpm. <br /><br />I would simply ask him what he did. Although I'm sure if you paid him and were not happy, you already have asked. What did he say?

 

[Solittle]

Re: What did the mechanic do???

DH - It is a puzzle to me also. The props are the same. The mechanic said that he adjusted the carbs. He also suggested that I replace the T-stats which I did. I have also decarbed since the trip to the Keys.<br /><br />The rpm values I gave in the post when in the Keys are not WOT but where I like to cruise at. WOT now is about 5200 on one motor and close to 6000 on the other. The motor with the 5200 seems more sluggish that the other. Before (in the Keys trip) I think the WOT for both motors was around 56-5800 though I seldom run at that speed.

 

[plywoody]

Re: What did the mechanic do???

Ok, but you are flaunting the laws of physics here. Unless something else is going on.<br /><br />You cannot have the same boat with the same props turning a higher RPM, and yet push the boat slower. It doesn't compute.<br /><br />John

 

[Hooty]

Re: What did the mechanic do???

Is the plug in?<br />Not being cute here but it sounds like you've (the boat) gained weight.<br /><br />c/6<br /><br />Hooty