Top speed???

[Supra-in-steamboat]

I second what Lively and Chris Young are telling you. Jetlink has stellar advice as well. Do your research. I have 4 props. At sea level a very aggressive 4 blade CNC Nibral sent my 87 to 46mph quickly. At 7500ft that prop would take 30-40 seconds just to get on plane with no weight and 1/4 tank of gas. Add a .60 cup 3 blade 10.5 from Acme (ballast prop an older acme 913 -new ones are.80 cup) and it will rip the rope out of your hands and do @39mph at @4100. Is it possible there is some crap in your power valve?

[Blackntan90]

For info I run WOT at 42 mph and 4400 rpm- Just as it says in my manual with a stock 13x13 prop at less than 1000 ft elevation. I have added alot of weight to her over the years in accessories(tower, tunes, misc. crap), and my bimini acts like a sail and probably slows me down a bit.

[carlossa]

I would check your timing first. Cost you nothing to throw a light on it. Flyweights in the distributor could be frozen and not advancing through the rev range.

[SquamInboards]

I would check your timing first. Cost you nothing to throw a light on it. Flyweights in the distributor could be frozen and not advancing through the rev range.

While I may have just come out saying "get a prop," I completely agree with this. A new prop can really transform a boat, but it does have to be running right to begin with. As far as the cost, you can work with a shop that will let you try one, and if it doesn't perform the way you want they'll give you a different one until you're happy. Not all shops will do this but some that have been mentioned certainly will, and maybe someone near you would do it for you too. But definitely checking timing is a good idea since it's FREE if you can get your hands on a decent light.

The more info you have and the more confident you are that the engine is performing properly, the better experience you will have looking for a new prop to take you the last 10% of the way to excellent performance. I've seen boats with new (repower) engines gain 2mph @ consistent RPM with a CNC prop over the old one. So once you get in the neighborhood, the right prop can really dial you in.

Good luck, and keep us posted with what you find. There's a lot of collective engine knowledge here to steer you in the right direction.

[cadunkle]

Check for full timing advance, you want 32*-38* full advance around 2500-3000 RPM. Check that your secondaries are opening, if vacuum it could have a ruptured diaphragm not opening or not fully opening.

WOT RPM should be ~4500, give or take a few hundred depending on prop. My Saltare does ~44 MPH with a CNC Acme 13x12 and with the original cast OJ it did ~50 MPH.

[biggsie]

Timing light has been erratic... Works ok at idle but cuts out and acts funny at 3k rpm. New dist going in this afternoon. Funny thing is that the boat seems to run great.


Sent from my brain using Tapatalk.

[lively]

Get a new timing light ?


Sent from my iPhone using Tapatalk

[biggsie]

It is a very new digital unit that works great.

Just pulled the old dist and the guts are all rusty and crappy looking. Fingers crossed.... New one goes in soon.


Sent from my brain using Tapatalk.

[lively]

Pictures ! I wanna see !


Sent from my iPhone using Tapatalk

[biggsie]

Too late for pics, it's gone to the core charge gods.

New one installed and set timing to 10*. Instant gain!!!
40mph and 4200rpm. Not too sure what the factory timing curve is but I may just leave it be.


Sent from my brain using Tapatalk.