1998 convincer 330 2x454 props?

[check303rcng]

hi im new here i am 3 time checkmate owner and i have a problem hopefully someone can help me out i have a 98 convincer 303 2x454 310 hp i have power tech 22 4 blades on the drives top speed is 62 mph at 4600 rpm i know this boat should be doing 70 mph can somebody tell me am i proped wrong or is there something else wrong with it thanks ALAN

 

[check303rcng]

hi im new here i am 3 time checkmate owner and i have a problem hopefully someone can help me out i have a 98 convincer 303 2x454 310 hp i have power tech 22 4 blades on the drives top speed is 62 mph at 4600 rpm i know this boat should be doing 70 mph can somebody tell me am i proped wrong or is there something else wrong with it thanks ALAN

 

[Shameless]

First, welcome to the board. Second, how are you measureing your sppe, gps or speedo, if speedo, what brand? Third, who told you that you should run 70 with pretty low horsepower and 4 bladed props? I personally have never heard of power tech, but for your set up, Mirage plus's would be a faster prop. You have alot of boat for only 620 hp. Also what is the condition of the bottom of the boat? Is it clean, is it straight? Are the props or skegs nicked or bent at all? There are many variables, I hope this is a start.

 

[check303rcng]

hi bill and thanks 62.7 on gps the bottom is clean skegs are perfect i keep it in the air in my back yard the boat only weighs 6500 so 620 hp is pretty sufficent for the weight of the boat power tech is a good prop alot of info on the net but is it possible the the 4 blades are to much prop for the boat do you know what the stock props were ?

 

[Shameless]

The stock props were probably Mirages. It is not that a 4 blade is too much prop, they are better for mid-range acceleration, hole shot, and better cruising. They are a little slower because of the extra blade. In a single application, a person would normally loose about 2mph, so you are probably looking at a 3-3.5mph loss with twins. When I worked with thes boats, we always put Mirages on them but we never powered with less than the 454 mag (385 hp). I would say that almost a true 63 it real close with 4 bladed wheels. We used to run the 454 mags at about 70-71 on the Merc speedo which is about 67 on gps. Also, most manufactures would list your boat as a 32 footer because they include the platform where checkmate did not. So, you have a big 30 footer. I must say though, the 303 is an awesome rough water boat, I used to run them on lake mighigan, and the boat never groaned at what the lake threw at it!

 

[check303rcng]

thanks bill i love the boat its awesome in rough water i run the ocean all the time with it plus its the most boat for the money so back to the prop story if i went with a mirage 3 blade 23 i would gain aprx 3 to 4 mph if so would you remeber the exact size prop pitch diamiter the whole nine yards i would really appreciate it 3 to 4 mph would put a smile on my face

 

[Shameless]

I am sorry I don't remember, but you can call Mike Combs at Checkmate, he is a wealth of information, and a good person to get to know. His number is 419-562-3881, you can either ask for Mike, or parts. Anything you need for your boat, he can probably get too. Just incase Mike asks, you might want to have either the boats hull number or if you can find it on the dive, the gear ratio for him. Good luck

 

[disturbed]

hey 303,
I am not disagreeing with Bill at all, because he knows far mor about mates than myself. i have been battling with props for about 2 months now. I have a 260 convincor with a 454 mag(365).I would try a couple of bravo 1 4-blade 22's. they are acually almost a 21 p prop,so you will pull another 200-300rpm because the rev limiter is 4900 on those engines. then you will still be able to come out of the hole alot quicker than with the mirage plus's. that should get you up to about 65 on gps. Try it. Just trust me.

"I LOVE THE ARMY"Where else can you travel to beautiful places, meet foreign exotic people an KILL EM !!

 

[Shameless]

Ditsturbed is right, I would say find a dealer who has a couple of props that you can demo, then buy what you like. Checkmate and I thought the 22p Brvo one would work on my boat, it turned out to be too small, so like disturbed, back to work on finding the right prop. Disturbed, I spun the 22 Bravo 1 up to 5300 rpm's, dead calm water, about 60 gallons of fuel, 4 people, 42 beers and ice, though as the hours went by, the beer count lessoned!

 

[check303rcng]

hi bill i spoke to kip combs today and he was pretty helpful and he told me i was running about 5 mph slow his brother was on vacation and he told me to contact him next week but its real nice to know that the people who own the company are there to help you when needed if and when checkmate builds a 38 mark my words i will own the first one

 

[disturbed]

Hey Bill,
Since iv'e got ya here. My 454 mag is blowing out some serious black smoke when i cold start it. it goes for about 15 minutes and then it runs good. It almost quits if i don't keep it about half ass on plane in the marina. is my carb bad or does it need to be cleaned or what? There have been no adjustments made since i got it, and it has always run very well. I'm running 93 octane in it.What do i need to do?

"I LOVE THE ARMY"Where else can you travel to beautiful places, meet foreign exotic people an KILL EM !!

 

[Shameless]

Disturbed, by what you are saying, I would say buy some Power Tune by Mercury and clean the card and Make sure you have a new water/fuel seperator. You might want to reconsider running the premium unless you have raised the compression on your motor. If the motor is still stock, run 87 octane, that is what it was made to run. Two big mistakes people make with fuel is running higher octane when not necessary and running alcohol based fuels. Running premium in a stock motor can cause detonation, and alchol, well lets just say too much to list for now. Everyone should keep Power Tune on hand for carbs and EFI motors.

 

[disturbed]

hey bill,
there is not a water/fuel seperator on my mag. The compression in the motor has not been beefed at all,But the local dealers all say to run high octane in the motor. How do you clean the carb with power tune ?or do you put it in with the fuel.never heard of it before. Guide me through this a little.

"I LOVE THE ARMY"Where else can you travel to beautiful places, meet foreign exotic people an KILL EM !!

 

[Shameless]

Please, do not take this comment wrong, I am not trying to be a wise ass here... Read your owners manuel on fuel. The only reason I claim to know what I do about fuel is beacause I was told to go to a school, partially put on by Mercury at the time regarding fuel. It wa around the time alcohol based fuels were coming out and it caused havoc with motors. Refresh my memory, what year is your boat? It was around 93 that Merc started putting water/fuel seperators on all of their motors, at least the V-6's and V-8's. If you really don't have one, you should install one, very easy to do. As far as the Power Tune... You buy in in an aerosol can, follow the simple directions on the can, but essentially, you warm up the motor, then spray it into the butterfly valve on the carb. You will need to take off the flame arrestor to do this. High octane fuel is not only wasting your money, but can potentially damage an engine that is not designed for it. Small displacement/high revving engines with high compression, generally hihger than 9.8 or 9.9 to 1 requires high octane fuel. Your motor shouldbe around 9.0 to 9.5 to 1. All oxyginated fuel or alcohol based fuel attract alot of water, for every 10 gallons that sits for 2 weeks attracts 1 quart of water. Also, if you do not have alcohol or oxyginated fuel, and have "regular" fuel, winter storage is very hard on the fuel. You essentially create a rain forrest atmosphere in you tank from the temperature variations and closed quarters. Basically a greenhouse effect. THose water droplets that form in your tank, fall into the fuel and sink to the bottom, water is heavier than fuel, that is where the fuel pick-up is. I am willing to bet you did not have this problem at the end of last year Disturbed, but started this Spring. Alot can depend on where you buy fuel and even comes down to what day you bought fuel because of winter blends and all that sh** Trust me on this, once the water is out of the tank, install a water fuel seperator, power tune the carbs, and by 87 octane fuel, that is until you slap the Super Charger on, then switch to the premium. Most people are still very old school when it comes to fuel, even dealers, but trust me, after a week up in Northeren Wisconsin talkink about fuel, this is onething stuck in my head.

I have to run out now for some follow up doctors visits with my wife, but i will check back this afternoon for any more questions or feel free to e-mail me at fischerbill@msn.com

 

[Eriktheviking]

Hey Disturbed,
It could also be your choke is sticking and needs adjustment or replacement.I'm suprised you don't have a water/fuel separator.Every V8 Merc I've had was equipped with one.If you face the motor its on the left side by the fuel pump.(Looks like a white oil filter)