source of smoke?
 

My boat is 16 years old. When the engine runs it smokes just little bit. After i run the engine wide open and slow down to near idle speeds it smokes noticibly more for a few minutes. Is this a sign of my piston rings are going bad, or what would cause this. I suspect 50-60 hp has gone out to the pasture, but the shop tells me compression is good

Is it smoke or steam? Do you have through hull exhaust? If it is smoke it could be a lot of things. Rings, valve seals, the list goes on. If you want more power fresh-in it up.

Do a leak down test to check the rings thoroughly. If that comes back good, then it is probably valve seals.

if its 16 years old would you really consider just fixing what you might identify as only one weak area ?

EVERYTHING in that motor is old. would you just do the rings or valve seals and put them back on 16 year old bearings and bores ?

just rebuild it and get it over with the first time.

How much should i pay for a engine rebuild? And in the process would it be best to keep it stock, how much more would it be to get it to 420-450hp. Can the bravo drive handle that power. From what ive read this hull should do 70 with around 400hp. my best is 61..

OK, first off was that the "Dream O meter" or GPS. You need to give more details about your boat if you want good info. What type of boat, lenth, model, drive type, drive height, prop, ECT...

Boat is 93 rinker 236. closed bow. 502 mag carb. Prop is 23mirage plus. Last year it was spinning at 4700 rpm i could get 61 gps. This year it spins 5100rpm 61 gps??? Seems like a lot of prop slip to me. It has bravo with 1.5 ratio. Others have claimed 60+ gps with 330 hp 454. Old boat magazine archives from the early 90's report 63mph for 330hp, i think i saw 67mph for the 365 mag engine. It frustrates me I have a hard time getting 60 mph. This is on freshwater lakes in Mn

Your tach may be off, Rinkers gages are not the best. Your speed sounds normal. A friend of mine had one with the 454 Mag, 365 HP, 58 MPH GPS. Check out this website http://www.rbbi.com/folders/prop/propcalc.htm

If you want 70 MPH you will need 500 HP. You can't go by what people say, or a article that was written before the days of GPS. In the 90's the magazines would publish speeds to help advertisers sell boats. Almost all non GPS speedo's read 3 or more MPH fast. Either you can freshen up what you have for about 2k or you can spend 10k or more to get the 70MPH mark. This spring I did a roller cam upgrade through RMbuilder and I finally hit 69 MPH. I have a little more tweeking to do on it, when the humidity drops in the fall I should hit 70. Take a look at my thread "Roller Cam Upgrade".

Great advice.

Guessing- with no time crunch addition 4K to do a stock part rebuild. 1K for an in-n-out 3K for engine dis tear down/cleaning and freshening.

Better yet get an new shortblock and have you heads gone through, bolt everything up that works well (replace/fresh all or not?) and go boating.

If you want 70 you need a head intake combo cam and exhaust. good time to do this is in a rebuild. (this is what I would do but its not practical)

Really though if you are going to spend anything on it- just put it together with fresh stock/cheap parts and go boating dude.

Dont start the "circle jerk of speed" with a Rinker- more speed will lead to handling issues then you need steering, then tabs, then a bottom true....just clean it up and enjoy it for what it is.


UD