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CMC 10" not going high enuff

A

aaronmt

Member
I cannot figure why i cant seem to get more engine height the prop shaft is at 4" below the V. Maybe these pics will help is it possible to have the jackplate upside down? What do u guys think, I read somewhere CMC's adjustment nut is at the bottom but that was a 5 " this a 10" ad i have mine at the top. I cant believe my setup would be that far off it at 70mph with 4 people nd a tank of gas, but am running considerbale positive trim. I would like to lessen that with the prop shaft at or neer 2" below the v. Thanks Aaron
 

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What are you running for a prop? What else can you tell me about the setup? Boat, Motor, RPM bla bla...

The 10" is on properly, it looks like you have some additional spacer behind it, can the motor not go up more on that one? As well, with that spacer thingy you have gained zero lift and moved the engine about 4" back.

Lifting the engine is not going to help you carry weight better, it will be worse.
 
Ok the motor is 1987 yamah excel i have the 10" jack plate as well as a 2.5" cmc that i did drill another hole to allow for a lil more height. The boat has ran 74.7 on the gps at 6000rpm with a 25p quiksilver lightspeed/laser II and 2"bobs spacer ,minus the rear seat and very much out of control. I changed to the cmc becouse the bobs just didnt look right with that jack plate. this weekend i had a full tank and 4 adults and was running right at 70 gps / 75 on speedo it was at 5400-5500 rpms and rock steady but throwing a rooster tail becouse of the excess possitive trim . raise the motor should bring my rpms up a bit as well as lessen the positive trim, i think . but how do i do that. I will be milling the heads in the next week or so as well as jetting it the motor currently makes about 245hp soon to be hopefully 255-260hp with 10 pounds of more compression. The added hp should allow me to turn a tempest 25p but that does me no good if i cant get this motor higher then 4" below the pad. Thanks Aaron:thumb:
 
If you want to lessen the trim. Ditch the laser, get a Trophy or Tempest Plus to try if yoou can. They carry weight alot better. The holeshot on either of those props can be adjusted by the PVS plugs. The laser can be a fast prop on certain boats but it doesn't carry a load well.

Typically when you start running higher engine heights, raising it will not allow you to use less trim, especially loaded. If you raise the motor typically you will run more RPM. The ideal running profile of a motor, if you stand on shore and watch it go down the lake, is perpendicular to the waters surface. If you have a roost higher than the top of the motor, or run at an angle in relation to the surface, you need to change your setup.

Can the motor go up on the 2.5" spacer? Those bolts look to be 3" from the top. If you look I don't think you have gained any height as opposed to just using the 10" jack plate. If you just go back and not up it is like running the motor deeper. Try going down an inch you may go faster with 4 people.

Be careful on those motor mod's. If I was going to play around with a Yamaha I would contact the Hydro-Tec guys in, I think, Missouri. They have a ton of experience and sell proven bolt on products. As far as your boat being out of control before was your dual cable steering adjusted properly?
 
Im not exactly sure if the cables are adjusted properly and not sure how that i would go about that. As far as the motor i contacted hydrotec and they did say they have different heads for it then then told me after a little prying that the heads they sell are 220 special heads that they mill. Then i went on to screem and fly and ever person there said as far as yamaha's go there are 3 places to look hydro-tec, ray neudecker and bob kottman. I then contacted ray neudecker and learned alot from him on what to do with the motor he then informed me my motor was never even advertised as a 225 in fact there was never a horspower rating offered and that they were close to 240hp having the best carbs as well as heads. He then informed me that if i go mod the air box to reget from 168/160 up to 174/168 then by milling the heads 15 thousandths i would be able to get close to 10 pounds more compression(these motors have domed pistons). Im hoping with doing the heads the extra compression would enable me to spin a 25 tempest with more rake causing more bow lift. The only way i can see getting more heighth with the spacer would be either drill another hole or bolting the spacer to the jackplate then the motor to the spacer:( , that in my opinion is an absolute no go. How are otrhers achieving 2 - 3 inches is my jackplate limiting my height 4" just seems very much baried as far as everything ive read. thanks for baring with me ive completey gone through this boat and am absolutey impressed that i think theres more left. Aaron
 
As far as adjusting the cables go... I assume that yoyu have dual cable steering with both cables coming from the same side? Wiggle the steering wheel you should have very little play before the engine turns. To adjust the play...Look at the front steering cable. There is a bracket bolted to the front of the motor through which the cable runs in a tube with threads at one end, probably half the length of the tube. There will be jam nuts on the tube, one on each side of the bracket. loosen the jam nuts, back off the port side jam nut and tighten the starboard sidejam nut on the outside so it pulls the tube & cable to the drivers side of the boat. Do this little by little while checking for play in the steering wheel. It ends up being a compromise between play and stiffness of the wheel. Retighten the jam nuts and you are good to go.

I think I get what you are saying about the spacers. I thought they were c-channel or something and bolted to the plate and the motor then bolted to the spacer. I guess they are solid or something. If it is, I think that is as high as you can go with that set up. Cook Mfg offers a 5" vertical extension.

http://www.cook-mfg.com/


Or maybe you need a different jackplate. I really like the hydrodynamics rapid jack. The CMC in the all the way down position has the motor at the same height as being bolted to the transom. So you go back 10" and only gain 4" vertically... Poor design. If you look at the hydrodynamics jack in the picture you have gained a couple of inches in height before you raise the plate one iota. They are great to deal with give Chuck a call.

http://hydrodynamics-usa.com/index.php?option=com_content&task=view&id=24&Itemid=46


So if you were to ask me what I would do to get the most out of that boat... Well, I would, especially when I read this thread started by Mark...

http://checkmate-boats.com/forums/showthread.php?t=2158

1) Buy a 12" HydroDynamics plate. Then try and dial in the boat with the prop you have.
2) Once you have done all you can with that I would round up a Trophy Plus or Tempest Plus to try and adjust from there.
3) Leave the motor alone. Modifications are a pain in the ass. You spend a bunch of time and don't gain much. You can end up with a bunch of grief. A ten 10hp boost might get you 2 MPH.

Ah yes, the old acrinom B.O.A.T. "Break out another thousand"
 
You can put wedges behind your plate so that the motor lifts more vertically but not sure exactly how much you'll gain. The further you go back the higher you need to lift to maintain optimum setup cuz as you go back your burying the motor.
 
Ive been doing alot of looking has anyone tried the vance mfg/ carolina jackplate they have them for 225hp as well as 300hp in 12" set back i imagine the 225 would be fine . Any thoughts on them. they seem as to be set almost 2 inches higher to start off with then the CMC. Thanks Aaron
 
In regards to getting a new Jack plate. Would I be best off getting a 12" or a 14"? and if I went with a 14" what kind of bracing would I need or should I use on the transom? :rolleyes:
 
If your going to go further back yu would be better to put a small one on top of what you have or your going to bury your motor more. Mount the new one as high as you can on the old then you should be able to get your motor back up to a good ride height.
 
Blizz said:
If your going to go further back yu would be better to put a small one on top of what you have or your going to bury your motor more. Mount the new one as high as you can on the old then you should be able to get your motor back up to a good ride height.
Click to expand...

I disagree. To me, he is better to get rid of the current plate and spacer that he has and install 1 - 12" jackplate that starts off with built in lift rather than two bolted together. Just about any jackplate mfg makes their jackplate so that even all the way down there is an increase in engine height, except CMC. Like Aaron pointed out with the Vance unit. CMC's design is ok with a 6" unit but with 10"+ it sucks in my opinion.

Go to CMC's website at look at the photo of the ten inch plate. The mounting holes on each side of the plate are in line with each other in the full down position. Because of the natural transom angle, you can really only lift it maybe three inches more than having the motor installed right onto the transom. Go look at the purple jackplate in the Hydrodynamics link that I provided previously, in the full down position the motor mounting holes are at least three inches higher than where it mounts to the boat.

You shouldn't need to run more than 12". One thing you may want to consider is a skid plate for that jack as well. 12" of setback is alot in my opinion.

Call Chuck Goodman @ HydroDynamics and talk to him. Make sure you know how tall the transnm on your boat is to start. He has a ton of experience and will give you some good advice, even if you don't go with his product.
 
So what does everyone think about the vance mfg vs the hydrotec there abot $130 difference between the two . Does anyone have the VANCE MFG and can tell me how they like it , the best price ive seen on the hydrotec is $367 does anyone know of a better price ive seen the vance for $272. Thanks Aaron
 
Well after comparing weights , i decided to go with the vance i was able to get it to shipped to me for 298.00. From the looks of it, it should start out almost as high as im at all the way up. I think the CMC 10" is a great piece justnot the right one for this particular setup. I will be able to have it on by sunday i hope if it shows up friday becouse i work till saturday or it be on friday evening.:confused: I hope to be able to raise my rpms a little bit i will set it at 2" below the v and see what type of water preesure there is at 4" im at 20 psi and id like to stay neer 10psi. pics to come. Aaron
 
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