It is confirmed, Bob Madara will do the cams and provide retro roller lifters as well , I will get the cams specs on Monday but he estimated hp to be over 400's :thankyouthankyou:

Way to go Diego . Wise choice .

I do have mirage 25p props , any opinion on these? They originally came with stock 454's On this boat.

I mean ,would I be able to reach 5000 rpm with these props?

If you are running Bravo's with 1.5 gears i would speculate the stout 383's will give you equal RPM to the 454's...+200~300 RPM.

Ask Bob Madara where your sweet spot will be. I'm guessing 23's will give you more "snap" and better over all performance.

Hey Man...I'm thinking our boats are going to be about as close as 2: different brands can be. Mine is 25'-5" Center Line bow to transom, 8' beam and 24* dead rise with a dry weight of about 5600 with twin SBC's.My 355" Vortecs with Comp rollers make 400 horse at 5100. With mine I am toying with the idea of Revolution 4's in maybe a Labbed 22~23 to max the RPM at around 5200. I have no basis of comparison for my 255 due to the fact that there aren't many left around. The closest Formula I have to compare to is the 272 LS thru the '80's but none of them came with Bravo's. I'm going to launch with a pair of Mercruiser "Old School" 21" Stainless Steel that will get the engines broken in....but I'm not expecting any serious performance until I start dialing in a prop.

I am very anxious to see what Bob dials in for your rig...and really appreciate you sharing the info...after all...we are the best testing lab out there. :evilb:

I am curious about your set up with the Bravo I's and the SBC's. I decided to forgo the thru hulls and strainers for water supply and pull thru the drives using crank driven raw water pumps. What is you plan? I am going from old "Log Style" exhaust manifolds and "Pre-Alpha" drives to Vortec "Center Riser" exhaust and Bravo I drives. Talk about your "Retro Fit"...I have had to change everything: hoses, brackets, steering ram, trim pumps, transom assemblies, bell housings, couplers, flywheels...not to mention changing over from mechanical to electric fuel pumps!!

Again...thanks for sharing what you're doing.

hey , of course , i love this site , the idea is exchanging info,it is very valuable.

i do have Bravo 1's , the reason i bought this boat is because i did not want a big boat to start but i shared with a friend a 34 silverton and i loved the idea of a twin engine from the get go, that is why i went with the Nova since i love the lines and overall look, we definately have very similar boats, i meant "retro fit" refering to the roller lifters that Bob is supplying me.

I will start with my Mirage 25's and then i would adjust, i like the idea about starting with something small to break in the engines, we'll see, maybe i can get a hold of a couple of cheap ones to get them started, but beleive me , my pockets have been suffering so much lately!!

The stainless marine set up was a pretty expensive upgrade, that i do not regret because of all the good reputation they have , it is boating after all $$$$$$ !!

thanks everyone again, if it wasn't for everybody's persistence on using Bob, i might not have done it.

I think a lot of people originally think the advice comes off as "mean spirited" since there is a lot of horsepower on this site in general, but usually it comes from having done it our way once and learning our lesson. It's a hard pill to swallow spending that extra money, since not all of us have $100k to burn on this hobby (though I wish I did!!!!) You'll be way ahead of the curve on this one. If everyone wrapped there heads around a little more now will save me thousands later we'd have a lot less advice needed in the tech section :)

I also like the idea of breaking in on lower pitch prop, I did exactly that when I had my 502 built. It's certainly not required, but letting her run a little more "free" is a real good idea. Even if you can borrow a pair of 21's just for a few hours.

Good luck with the rest of your build, and chime back in on results!!!

Thank you and of course i will get back with the results. I will try to borrow smaller props to start the process, it sounds good.

Cams from Bob Madara were Delivered to me today,here are the specs :

Hydraulic roller

LSA 112
Duration .50 222/228
valve lift .532/.524

I am expecting to turn these engines up to 5200 rpm

I will post results in about a week,

Thanks everyone again , it was a pleasure to work with Bob, hopefully outcome will be just as good.

:whistle:I would love to get some opinions on the cam specs above design by Bob , well I guess if they were design by Bob Madara, the name says it all,right?

My take is with that lift he is really building some cylinder pressure...and quickly. That's a big advantage of roller cams...you can do things that are for the long haul with lift that you marginalize the durability with a flat tappet. Running that lift at that duration in a heavy boat wouldn't last very long or be very well mannered at the dock with a flat tappet set up. It will be relatively smooth with a roller. He custom tailored that grind to your exhaust which is capable of getting those gasses out quickly.

Your boat should get up on a plane fast and run like a "Raped Ape" all the way to the top. I look for a very strong and fat torque curve.

I pretty much agree, I certainly won't speak for the man, but the lift numbers he gave on my cam were WAY higher than I expected. This will put some extra load on your springs, but the roller engine can handle it, though I do plan to do springs about every 300 hours. All I know is Bob helped me assemble the proper stuff and my boat runs real string for what it is. In fact a friend runs a 201 Liberator (typically about 3-4 mph faster similarly powered vs. my hull) that is about 2 mph slower than my boat is now with his assembled component 502. He did it his way and saved about $1000 to his credit, the boat runs fine. But the endless stream of grief I've been giving him is really starting to irritate him AND I don't need a can of ether to get mine to start, I need two cranks ;)

Now I won't say you can't duplicate his results on your own, I'm not that naive. But if you don't know or are way off, he sure quickly steers you down the correct path. That to me is worth more than the minimal price difference to an off the shelf cam. And most importantly he listens, to what you wants and needs are, because lets be real it's not ALWAYS about max power...it sure wasn't for me

Going from a Gen V 502 with SM manifolds already on it, to a roller conversion with full roller rockers, a bob cam and an edelbrock intake, I picked up 7mph, in the boating world that is HUGE.

I just told Bob do it as if this was your boat, and that is what he did of course he mentioned he would not compromise durability , and I liked that, i will post more info as soon as get the boat on the water.

Thanks for your input!

I agree, 7 mph is a lot of gain, by the way, Bob spoke to Edelbrock tech support to make sure the springs were acceptable and he even gave my builder some recommendations as far as adjusting them a bit.

Very eager to seeing results now.

Thanks for your reply.

Are these specs with 1.5 or 1.6 ratio rockers?

These are w 1.5 ratio full roller rockers.

So what did they make?

UD

Uncle Dave,

I am still waiting for him to finish them up but I am also changing the seals on the drives,changing gimbal rings ,shift cables ,bellows, and every other part in the gimbal housing.Once I am on the water I don't want any big surprises.
I wish it was all ready by now but is not as fast as I wish I have some pics taken 1 weeks ago will post them next.

here some pics so far
 

still waiting, but hopefully it will all come out good. Thanks everyone for your input

I had a lot of play in the drives and since engines were not installed yet, decided to make sure eveything was right with the drives and gimbal housing.

Smart...take advantage of the down time. Once it's all back together you would be kicking yourself for not taking care of it when was easy.

I am is the same process my friend...no rush...we boat year round here.

Thanks, even though my pockets are suffering, I am going the extra mile because,it would cost me more later when engines are in plus the aggravation,plus plus plus. PM sent to you

We tried to use the tall valve covers also but they would not work with Stainless Marine manifolds, But the short valves covers will with the thick gaskets.

As we were putting them together to take that pic ,we realized that, you have clinic eyes! So which ones should I use? Short ones?

These look like they will work from Summit part # bsp-95127 they are $127.95, But any thing stock should work. We did use a thicker gasket like the Edl-7549 $18.95 .313 thick should be fine. I found out that the tall ones would not work after they came back from being powder coated.:lolhit: Good luck !!!

Paint the stock ones blue and be sure and put several coats of clear on that polished manifold...if not it will turn fast down here in our "world".

Good work never goes quickly.

I replaced the gimble on my 500HP 406 21ft tunnel 3 times in 15 years- just wore them down. I switched to external steering and that stabilizes the gimble and extends life greatly.

Im excited for you- the new mills look great and you used good parts -the rig should rock balls!

Thanks for documenting all this for us- its been a great ride with you!

UD

I used tall Edelbrock finned covers but had to heat and "clearance" them slightly to fit with stainless manifolds. I can still get them on and off

http://i225.photobucket.com/albums/d...ps40269ad1.jpg

Ok here we go again, after the advice of most of you , I decided to keep beating my pockets and got 2 sets of FWC kits from Michigan Motorz , since I have aluminum heads and intake,and after reading on several threads I realized a lot of people were toasting their aluminum heads after two years or so by running on salt water like I will.I read this happens even after flushing every time you go out.
Phill took care of me $$$$ and he helped me get the right one for my appl.
It was a hard decision $$$ but I thank to this website and the many valuable members on it that with no interest are trying to give the right advice for begginers like me.
God Bless America !!!!!

Those look beautiful !

That thing done yet dude?? we got a sea trial to go on!! haha glad everything is working out well brotha!! Keep me updated.

Uncle Dave,

Thanks for your support

Greg,

How are you? Yes, I know it has been a while but still hangin' in there, and i will definitely let you know when we are ready.

My close cooling kits are getting here this Wednesday, did i do the right thing by spending the extra $ ?

No question about it.

Will you be dynoing these?
Does the boat have full hydro steering?

Sitting here reading this thread and learning a lot. I too am going through this tough time with engines. I have a 29ft. Scarab, twin Vortec 5.7's, MPI fuel delivery, advertised at 300HP, 1.5 Bravo 1's, 23p Mirage Plus... One engine shattered an exhaust valve. Did tons of checking, asking, reading, and pretty sure the cause was from a riser gasket leaking.... To fix the problem ..... Going back as 383's .. parts are: Eagle rotating 400 steel crank, forged 5.7" rods., dished hyper .030 over pistons, vortec heads with match port(machineing valve guide down), holley MPI single plane intake (2000-7000), full roller rockers, comp cam XM270HR (int-.495, exh-.503, @.050 int-218 exh-224, int centerline 110, lobe seperation 112, RPM range 1500-5500. Will use stainless marine or emi manifolds. The boat ran 68 on GPS @4900, 100 gals. of fuel 2 people.... dont know what my results will be... I am going to get them dyno , one shop can do prop dyno, the other is engine dyno. I am more concerned with being dialed in right (fuel, timing), but will like to know HP/T ...... I would really like anyones honest input on this.... first engine is about half complete....

I have the exact cams in 357 Vortecs w/ Vortec Heads,1.5 Comp Roller Rockers, Dual Plane Edelbrock w/ 750 DP Holley's. Mine made 400 horse at 5200 and 435 Ft. Lbs. @3500...TQ Curve is 400 + from 1800 to 4000. Dyno runs were with automotive headers and I will be running new style MerCruiser Exhaust....so subtract 25 HP at the top and keep the TQ high.

Based on my results I'm throwing a guess that you will make 450 HP in the low to mid 5K RPM range with TQ around 450~475 Ft. Lbs.

The 383's with the same props with 900 HP in the water will run a solid 75+ predictably...biggest pick up will be in the snappiness of the boat as well as a stronger cruise with a load.

I talked to Diego this afternoon and told him if I had it to do over again I would build a pair 6.0/6.2 LQ9 based motors and run reliable N/A 500 HP....but that's the next boat.

+1...especially with aluminum heads in our environment.:evilb:

I am looking for a place to dyno these engines.For sure.
No hydr. Steering .