What props and what hp??
 

Hello just trying to get a little info on props on the 92 checkmate convincor 251. My boat has about 500hp at the prop and so far a 26 4 blade bravo works the best for speed and rpm, I want to be around 5200 rpm . I tryed a 26 hydromotive and it was very unstable it felt like the only thing in the water was the prop.I did call hydromotive and they told me to try a 24 they said there was to much tq for that prop, any body got some insite on this?


like what hp
year
hull
rpm
speed
and prop hydromotive,bravo,3or4 blades

Thanks alot

500 HP AT THE PROP
 

Give me a call at 281-580-7767 and I,will be glad to help get you dialed in.Darin;)

I think we have determined that Checkmate used different x dimensions on various 25's. We am running a 23 Mirage and it works great. Others can't get on plane with a 3 blade. BTW, we have a stock 454.

Hello,

I have a 251 Convincor, year 1997 with a 500 EFI (gear rotation: 1,5:1). It runs between 78 to 79 on speedometer and 73,4 on GPS with a 27 Mirage plus at between 5200 to 5300 rpm depending on the people and fuel on board and the water condition. Normally the boat runs on flat water and there are no waves. Does anybody got an idea how to get the boat run faster? Does anybody got any experience with a shorten Bravo One? Or does anybody of you ever changed the gear rotation from 1,5:1 to 1,36:1? In my opinion the engine got enough power, but it is very difficult to find the proper prop. In Germany only a few people using the pitch I would need.

In the past I have not written anything for quite a long time, but I had so much work and was not able to. But I promise to do better in the future.

Hello Wild Willy,

well it seems that I do not have many options. But with a shorty drive you should have less water resistance, shouldn't you? There must a some possibility? Does anybody have experience with chip tuning on the 500 EFI? Perhaps, somebody else got any idea.

I am not at home this week-end, thus will answer as soon as I return. Take care.

Hello,

There is said that Mercruiser got a new five blade prop. In Germany the information flow is very slow and I am not able to get any at all. Does anybody has tested it aleady and what kind of experience do you got?

By the way we had our first Poker Run on the Rhine River which was organized by my friend Mike and me. If you are interessted, you can have a look under www.Boote-Forum.de (its posted under the category offshore). There are really a lot of pics.

Greetings from Germany (todays weather: raining)

Liquidator

I also have that same question I have a 1991 251 GTX Convincer. I am running a 23 3 blade Mirage this is the new that came with the boat. About 2 years ago I needed to get it redone so I went to Marysille Prop West in the Grand Rapids area. I have them add cup and fix it and they cleaned it up. It was around $110.00. The last year we went though the motor. Nowthat prop doesn't work like it use to. I have tried a 25 mirage 3 blade it was OK but still not the same. I also tried Bravo 1 Lab 26 the boat was not the same no bow lift it ran nose in the water and no top end but the midrange was very nice. Any help would be nice.

Hello All Trimed Up,

in order to give you any advise, I need more information on your engine (what type, what year, hp, rpm, etc.). Regarding your 26, I have borrowed a 26 four blade from a friend of mine and I found out that it is a good midrange prop without any problems with the bow lift. Check your trimtapes.

Greetings from Germany.

Liquidator

Hey Liquidator
The new motor is only slightly changed 454 BB it's a Mag. Older 1991 it's still stock on the outside. It had over 650 hard hours on it so it was needed. All new stuff inside rings,cam,all the bearings and a head job. The work was done by a friend Valako Race Heads. (Jim and BJ are great) After all this we sent it to the dyno at Earhart Engineering in Gun lake. It made 440 hp at 5500 rpms with 36 degrees of timing. Now I have to burn 93 gas. The good stuff or they say I can burn a valve. I hope this helps.

Hello All Trimed Up,

It is very difficult to discuss your problem via the forum, because I cannot look inside your engine. If it would be my engine and it would loose performance, I would do the following things:

1.) Check the compression, but be present.
2.) Check the ignition timing.
3.) Check the carborator.

There must be a problem somewhere. Further, I would ask the person who had redone your engine, if he had drilled 0,25 over on all eight pistons. Because, if you change only the pistons rings on an engine which got over 650 hours, then it got only for next 15 to 20 hours a good compression, but afterwards it is gone. I suggest you to not run over 5500 rpms. Keepan eye on your valve springs.

It is sometimes a bit difficult to understand each bit of your technical vocabulary, especially the abbreviations. If I understand correctly, your engine runs at 5500 rpms with the 23 3 blade and then you should run at approximately 5200 rpms with a 25 3 blade. I hope, I was able to help you in some way. Good luck to you. If you have any further questions, do not hesitate to contact me.

Greetings,

Liquidator

OK, finally talked to hydromotive today. (Tod)
With my 90 251 convincor, (425hp, 502) he suggest that I start with a 25p QIV. He actually said a 24" first but did some research on past "same" boats and said that what i should do is go with the 25", run it, get back to him with the numbers and he would lab it and bring the diameter down to pick up the rpm to about 5100-5200@ wot.
I'll post what i come up with. Will have the stock 25" next week.

Great guy to deal with and I like there policies on returns and exchanges.

Liquidator
For the question about compression I'm sorry I did not add somthing. The motor has ALL NEW STUFF in it. Pistons as well, so I hope the compression will be OK for a long time. The motor was machined and balanced as well. We spent alot of money on this boat in the last year so it better work, better than it did before. It has to, before it had 365hp and now it has about 440hp at the dyno. So we now that part of it works. I think the problem is in the boat mainly the drive height. The boat will not cruse very well at all. This thing is out of the water more than it is in. When I put the hammer down it runs fine. Anything over 50mph the boat runs on the pad just the way it's designed to. The three blade props are the fastest I hear but I would like the best of both worlds fast and safe. The boat does tend to chine walk at top end. Can make my wife and kids yell at me to slow down.

I run an 86' 251 as well. The Mirage three blade runs the best for top speed but it chine walked real bad. I added Full Hydrualic steering (twin ram Imco) and relocated the trim tabs (Bennet 12x16) inboard as far as possible. This has helped reduce the chine walk problem, then I tryed a 4 blade hydromotive, while I have increased my plane time and reduced my top speed, it has INCREASED my cruise speed, I now cruise at 65mph @ 4500 rpms with a rock solid ride. I think my next move is to try a Imco 2" shortie, I feel that will put me in the mid 80's but I am afraid my chine walk will then return. If so K planes will be next.

dlbcheckmate
I have thought about full hydrualic steering as well. I also thought aout a stand off box too. But not now no more money this year. I know some one at the shop Valako's I mean. That has one it came off a 26 checkmate one of the ZT I think. He saw some good speed out of it. He has the boat for sale at Premier Motor Sports in Gun Lake if anyone knows someone that needs a good used boat. So he doesn't need it anymore. That was the 26 lab bravo one I used. It is for sale also. But back to our boats mid 80's thats fast. How much hp does that take. A good friend had our same boat and had 740hp out of a 540. He used a 3-blade mirage lab 25 with cup added. Same problem chin walk a top end. But that boat is sold too. But with a stock 454 365hp.

I am currently running a labbed 26 Bravo in my '99 Convincor with a mostly stock 454 magnum. I can turn it to 4950 r.p.m., shows 75 speedo. ( I know it isn't going that fast ) I switched from a stock 24" Bravo, lost 50 r.p.m. but picked up a solid 3 m.p.h. I also added Imcos' dual ram full hydraulic steering. It made a big difference at speed. It is rock steady! No more slop in the wheel.

All trimed up, was that boat owned by Todd H ?

It was dlbCheckmate
The best that the boat saw was 89 at Hardy. Very fast but the same problem chin walk.

ATU, I bought Todds 468 he sold before he built his 540. I will be rebuilding at the end of this year, I would like to get a new short block (509) and reuse my top end (Valako wedge heads) but I will need to put seats in the heads, so I may get new Dart pro1's form Valako ? His motors make some power thats for sure.

dlb
Jim and BJ will help you when the time comes. They are helping me with mine right now. Are you going to use your other parts from the 468 or are you going the sell it complete. If I remember right that motor had all the good stuff on it. Dart intake with a big carb and dart heads and a huge cam. Still running good. His brother can build a great motor. His new boat is very fast over 90 in a 283 convincor. He helped me design my motor. But Jim and BJ built it. Steve did not have the time. He was working on his boat.

dlb
I just thought of some thing. Mr. Gadgets has a 509 in the corner of his garage under plastic. It was in his old 251 that looked like Todd's. See if he will part with it.
What do you think Gadgets.
Post sometime.

I think I am going to build that one and then sell it.. or put it in my Olds.. or .. who knows!!

Dick

Got my prop from Hydromotive this past week and ran it this past weekend. Didn't have a chance to get real numbers but so far it seems to work very well.
It's a QIV 24p.
Great hole shot, no cavitation, got on plan quicker, mid range pull is awesome, and it picked up 3mph on GPS(65mph).
RPM still seemed low (about 4600) but I ran out of space to play with trim where I was. Will play this weekend and post.

ps
Still got smoked buy a 38' cig, but I don't think that will ever change.:rolleyes: :rolleyes: :rolleyes:

Convincor,
Thanks for the info.Keep us informed.
Dave

Hi all I bought a 89 251 convincor about a mounth ago, it has a 509 in it with a dart intake 1050 dom healthy cam nice set of headers. runs excelent. I have some of the problems you guys are talking about ,loose steering,prop cavitates at take off and almost allways at 3500rpm. I also think it needs bigger tabs. I havent run it at full speed yet (need to fix steering first)but it pulls hard at 60mph. Hey All trimed up the intake is stamped valako if you could get me any info on my motor that would be great.If they remember it. The boat is black teal and gray and said checkthis on the side of it. Any info on how make this boat drive rocksolid be great.

What prop are you running???
Call hydromotive, they'll get you going in the right direction.

25p 3 blade not sure of the brand.

go to a 4 blade hydromotive.....
You'll be glad you did.
Read my previous post....

High Roller, you may want to try a Hydromotive QIV, if you are happy with your rpm with the 3 blade, then drop a few inches of pitch and it will drastically improve your ride. Also install hydraulic steering you will be a lot safer. Good luck and lat us all know how you are making out. Dave

Thanks for the info. I'm trying to make up my mind on how to fix the steering,so far hydraulic looks to be the way to go. I read over all the posts great info! i'd like to try the 4 blade. I'll let you all know what I do and how it works.

Highroller
I can stop over there and see if they remember.
My friend is having the same problem with his steering he is going to go with dual ram by imco. That might be what you need. Where do you boat.

All trimed up, Thanks for checking. I put in at Holland and go north or south at the pier head depending on the day. where are you guys buying the dual ram imco steering?

Highroller
I stopped over and talked to Jim. He thinks that your boat was first owned by Steve Rescola (last name spelling ?) or better know by Blue Moon. He sold it when he got his 30ft checkmate. But now he has his new boat a 36ft Apache. Very nice boat, it's brand new so it better be. So you must have bought to from the 2nd person. Jim at Valako's is a Imco dealer so that is were I would go first. And then check around. You boat around holland we go to Port. Shelden on Sundays you may see us. Steve is their too and you could talk to him their. We will have to talk some more their.

Thanks All trimed up !! I'll check valako's on the steering. Going to Grand Haven saturday (like everyone ) may go to portsheldon sunday.

Highroller,
We saw you at PS last saturday. Didnt know you were an oso member. You should have pulled in and chatted with us. Would have loved to talked. As far as steering you might want to check with Maxx and Alfster on the board, they are now producing a full system that is top shelf equipment at a very reasonable price. If you want his number I can get it, but I dont have it with me now. I know John and I would recommend his steering to anyone. Tell him I sent you..

Dick

Thanks Mr Gadgets, I also seen you. I was picking a friend and his wife up there and then seen some others. I wanted to stop and talk with you guys but didnt make it that far before you left. I'll stop in ps again and stop and talk. You guys all have nice looking boats! I like oso theres some great info. As far as steering goes I bought imco duel ram system and installed it this week,installes easy nice looking stuff. Makes th rest of stuff on the back look bad. I'm going out sat and sun to give it test, let you know how it works on my boat. THANKS for all the info from everyone!! Bob

Ran it in the river today and the best I could get was 65mph @ 5050rpms. Seamed to do better in the salt water but I didn't get much of a chance to run hard, water has been a little to rough.
Going to up-grade trim tabs over the winter, i think they will help alot in the rougher water.
Any body using the "Victory tabs"?