HELP. New boat, prop issues need education!
 

Hey guys, new on here. I reside in Central Kentucky and spend most of my summer on Lake Cumberland. Having a few boats in my time i have finally gotten to a boat I've wanted for some time now.

1990 Baja 265DVX. 502CI built with 650+ HP. Bravo I outdrive. Keel was taken out or modified of the hull.

Here is my issue, The boat came with a hydromotive quad IV prop 24P. It ran about 5100 RPM @ 64MPH NOT WHAT I EXPECTED.

So, i had been talking with Mark @ marks high performance props. He recommended a Bravo I 4 blade 26P. Bought the prop, dropped to 4200RPM at the exact same speed 63MPH. Since then i have had the prop repitched to 25 had the blades thinned out and cup taken out, got my RPM back up to around 4600 but still running 63MPH (GPS everytime). Needless to say i am very dissapointed with these type of numbers i was for sure this would be a 75MPH boat. Especially since the keel was taken out of the hull of the boat. Oh and the other thing, this boat comes out of the water like a monster! I mean the hole shot is better than any boat i have ever owned even with a prop that lets me tach at 4600. So, just looking for some help, advice, am i missing something here? Anything is appreciated guys. Thanks.

You sure you have 650 HP?? With that much actual HP, I would also expect speeds in 70's. Get specs on motor and post on here.. lots of motor heads on here that can help you out!! Slips looks OK, so it may be lack of HP.. sorry, but Congrats on the new boat nonetheless

Thanks. Yes I know the previous owner and the guy that built the engine. Dart heads, crane cam, solid lifters, 950cfm Holley, it has the power. Funny thing the low end and mid range power is unbelievable comes on plane in seconds effortlessly even when it would top out at 4200. I did just find the msd distributors advance is locked out...little confused there. Going to hook up a timing light and see what its set at. I'm thinking it may have just the wrong cam in it. Can't get dyno sheets but the boat is built for sure. Any advice or knowledge is welcome. I'm a gearhead myself but just enough knowledge on the water to be dangerous. I have an extra mkhammer distributor in the garage from a 454 I may swap them out see what that does.

By the way. Are you using some sort of prop tool? Which one do you use? All the prop tools i use say i should be at least in the 75-80 range.

What do you mean about the "keel taken out or modified" ???????????

There is no way to tell what HP the engine is making without some actual specs. Cam specs, head specs, what exhaust???
Its highly unlikely that an N/A marine 502 will make 650hp unless you spin it to about 5800rpms.

If you know the prior owner, what speed does he say it ran at what rpm???
Where is the engine build sheet????

I normally use blades slip calculator. To be honest I didn't check your slip but as i was running a 25 p m+, I was able to make an educated guess based in my slip, rpms speeds and a friend who is running 26p b1 and our #s were identical. As for top speed, having a 25 ol with only 385hp, 650 HP would that boat near 80, but I was conservative that you would run in 70s..prob high 70s if HP is there.

Problem is, the previous owner was 80 yrs old. He never had it up to speed and never knew how fast it truly went. I am finding more and more out. The "hook" in the rear of the hull was taken out, he referred to it as a keel. I did find the ignition advance locked out on the distributor. And the cam spec is a crane p/n 13SR00027 Grind # SR-246/362-2S-8 IG

Here is your cam specs. http://www.cranecams.com/product/car...detail&p=24626
Not what I would want in a marine engine since its a solid roller, but it should not be hurting top end HP. Its really too much cam for a 502.
It won't make its peak power until close to 6000rpms.

What is the timing set at????

Couldnt tell you what timing is at just yet. i am going to check it when i get back down there this weekend. So why wouldn't you want this cam, why do you think its too much for a 502? It doesn't idle rough at all. By the way, I've decided to put my 24P intimidator prop back on once i have it re-pitched to a 23, add parabolic rake and sharpen the leading edges. I am convinced the engine isn't turning fast enough.

If you weigh the boat with fuel and people and gear we can do a HP/weight calculation that will be quite accurate as to the speed potential.

Brett