Looking for advice on set-up

[Jet City]

I'm finding out all the details on my recently purchased Di Marco, what I'd really like to know is if the prop/gear combo sounds reasonable for this engine/hull. The engine is 440 inch BBC with probably 525-550HP (DD2000 guess), reverse manual turbo 400 trans, 18% over gears and 11 1/4" x 15 prop (2 blade SS). I have not had a chance to run it yet, next weekend will be first time out, just gathering input and ideas right now.
The previous owner ran a ton of down-pedal and was honest with me that the boat porpoises bad without the pedal, I have noticed the rear plates are slightly up from level without up/down pedal applied (I read level is correct), the other thing I've read is prop placement (for and aft) will have a dramatic effect on porpoising and such, is my thinking close to right?

[dmontzsta]

I'm finding out all the details on my recently purchased Di Marco, what I'd really like to know is if the prop/gear combo sounds reasonable for this engine/hull. The engine is 440 inch BBC with probably 525-550HP (DD2000 guess), reverse manual turbo 400 trans, 18% over gears and 11 1/4" x 15 prop (2 blade SS). I have not had a chance to run it yet, next weekend will be first time out, just gathering input and ideas right now.
The previous owner ran a ton of down-pedal and was honest with me that the boat porpoises bad without the pedal, I have noticed the rear plates are slightly up from level without up/down pedal applied (I read level is correct), the other thing I've read is prop placement (for and aft) will have a dramatic effect on porpoising and such, is my thinking close to right?
If the plates are set too high, that would definately be a good indication of why there is so much downpedal needed.

[Jet City]

Dmon, I kinda suspected as much, am I right in that the plates should be flat without pedals applied? Or is this at least a good place to start?

[Fiat48]

Is it a runner bottom or a flat? I can ballpark you with some measurments from a typical Cole type runner bottom.
18 is probably a little much gear. Depends on the prop. But if it won't carry the nose you probably need to try 12's. Maybe 15's.

[Kim Hanson]

I don't know about that down pedal stuff, mash it and when the front lifts hit it, and it will come back up and hit it again to take a set....I don't focking know, I have the rachet shit..stick it in place and go..........( . )( . ).......... :eek:

[dmontzsta]

[QUOTE=Jet City Rebel]Dmon, I kinda suspected as much, am I right in that the plates should be flat without pedals applied? Or is this at least a good place to start?[/QUOT
I am not sure about runners, but I know when my plate is all the way down, it is pretty much even, when it is all the way up, it is 1/8" up.

[coolchange]

Fiat's right, 18s might be a bit much for a 440. Friend had one with full roller 27 and he ran 6s. Boat was a bullet. Plates sound right at 1/8 up. What I see as your big issue is the trans. Its upsetting the balance point of the hull if the motor is in the standard location. I cant remeber?31" 33"? The real deal is in the prop and strut location but I think your a ways off from that.
Dmon, if your only getting 1/8" of travel you've got issues.

[Jetboatguru]

11 1/4x 15 and an 18 gear is gonna bring that motor to it's knees. It needs a smaller diameter prop and less gear. Leave the plates where they are. They should be on an upward swing when relaxed.

[dmontzsta]

Fiat's right, 18s might be a bit much for a 440. Friend had one with full roller 27 and he ran 6s. Boat was a bullet. Plates sound right at 1/8 up. What I see as your big issue is the trans. Its upsetting the balance point of the hull if the motor is in the standard location. I cant remeber?31" 33"? The real deal is in the prop and strut location but I think your a ways off from that.
Dmon, if your only getting 1/8" of travel you've got issues.
That is what I have it adjusted at, that is what I have been told was right.
When the t handle is all the way up, the plate should have a 1/8" gap if you put a level under the boat and cav plate.

[Jet City]

Thanks for the advice, I'm not completely confident about the gears and prop, it was what the seller told me and what I found in the paperwork. I will get the boat out ASAP to get a feel for it and make some more observations, the boat seems to rev-out just fine with the current gears, seems to pull fine to 6500 or so, its possible I've been misinformed about the gears/prop specs.
The hull is a 7/8" runner-bottom BTW.

[Jetboatguru]

He is talking about the amount of travel you have with the plates not the setting. You should have atleast an inch of travel and ideally over an inch and half.

[dmontzsta]

He is talking about the amount of travel you have with the plates not the setting. You should have atleast an inch of travel and ideally over an inch and half.
ohhh, I see...I am not sure what the travel is, I have yet to check.