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Looking for a 7.5 OB

Old 07-25-2006, 01:56 PM
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the german
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Default Looking for a 7.5 OB

Hi guys

I ' m looking for the most powerfull 7.5 Outboard Powerhead on the market ! Any idea ?

Thanx's for help
Old 07-25-2006, 09:00 PM
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Default RE: Looking for a 7.5 OB

I am currently looking in to the Rossi. I believe it would push a piped 7.5 tunnel over 50mph easily. I'm still in the same boat as you, and would appreciate any info on 7.5 mod power heads including the difference between these two Rossi's. Is one slightly newer than the other?

http://morrishobbies.com/product_inf...ducts_id=14004
http://hyperprod.bizhosting.com/7_5_...powerhead.html

Ryan
Old 07-25-2006, 10:51 PM
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Ron Olson
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Default RE: Looking for a 7.5 OB

Jim Irwin of Irwin Pipes fame had a CMB powered outboards for sale for a while. At $600.00 a pop, it was a little out of my price range. He had them set up to use a starter belt instead of firing it up on the nosecone/flywheel.
Old 07-26-2006, 04:32 PM
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Default RE: Looking for a 7.5 OB

I just sold it to rcmaniac, sorry
Old 07-27-2006, 01:36 AM
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Default RE: Looking for a 7.5 OB

Geets,
How close are you to Russelsheim or near Weisbaden? I'm near Hanau and always looking for people to run with.
Jamie

Did you get to go to Heilbronn?
Old 07-27-2006, 10:03 AM
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the german
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Default RE: Looking for a 7.5 OB

First ..... thanks Ryan and Ron for the info`s

Wiesbaden is just 35 minutes driving ( on the german Autobahn ) , my hometown is between Darmstadt and Mannheim !

Yeah , i was in Heilbronn on Saturday and i talked to some dutch guys who run MAC 21 outboards ..... nice boaters !

But no one knows anything about the Rossi`s Powerheads ... so i have to contact you guys in the great US [8D]
Old 07-27-2006, 12:01 PM
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Default RE: Looking for a 7.5 OB

They appear on the outside as only having the different colored heads. They did this also with their .21's, the Niagara's, Piranha's and Minarelli's all have the same exact specs, just different colors.
The first site is a new update though could it's possible that it is their latest release.
It's too bad that Andy and the gang at CMD didn't make a MAC .45 OB as there is a shortage of fast engines made. The class has just about died off because most people were using the K&B's. When they were sold to MECOA, it was (and still is) a shortage of parts.
Old 07-27-2006, 11:02 PM
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Default RE: Looking for a 7.5 OB

Thanks for the info. Do you have, or have seen the performance of a Rossi O/B? I only have experience with their 40 size aero engine. It performed well and seemed to be excellent in fuel economy.

Also, what is a good pipe to match the Rossi up with? I've been looking at the Silver Bullet by Precision Boats.

Thanks,
Ryan
Old 07-27-2006, 11:19 PM
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Default RE: Looking for a 7.5 OB

The Silver Bullet should be a good pipe to use on it. Jim Irwin did a lot of work with the Rossi's and found that they like to run a little on the warm side so if you dare to, restrict the water flow a little. I've found with my Rossi .21 that it seems to take forever to break them in, a good gallon or more of fuel so if you get one, don't be surprised if it takes a while for it to get up to speed. You may find that after break-in, you might be able to swing a larger prop than what others do. Start small then work your way up as the break-in continues.
Old 07-29-2006, 11:14 AM
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Default RE: Looking for a 7.5 OB

Thanks. Is it me or does Rossi actually use flat head screws on their cylinder heads? I might be seeing things[&:]

Ryan
Old 07-29-2006, 12:52 PM
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Default RE: Looking for a 7.5 OB

I can't see that well in those shots but mine has regular metric allen bolts.
Old 07-29-2006, 01:51 PM
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Default RE: Looking for a 7.5 OB

I'm having trouble postings pics. If you click on the photo in this [link=http://morrishobbies.com/product_info.php?products_id=14004]LINK[/link] it will be enlarged to a more viewable size.

Ryan
Old 07-29-2006, 02:03 PM
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Default RE: Looking for a 7.5 OB

Yup, it sure does! Most of the time they can be replaced and probably should. If they're Loc-Tited in it would be a good idea to.
Old 07-30-2006, 07:02 AM
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Default RE: Looking for a 7.5 OB


ORIGINAL: the german

Hi guys

I ' m looking for the most powerfull 7.5 Outboard Powerhead on the market ! Any idea ?

Thanx's for help
NELSON. Nothing else....
Old 07-30-2006, 02:53 PM
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Default RE: Looking for a 7.5 OB

Hey Mark

How much are they, and where do u get them? Do you have any experience with them?

Ryan
Old 07-30-2006, 07:18 PM
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Default RE: Looking for a 7.5 OB

ORIGINAL: ryan_t888

Hey Mark

How much are they, and where do u get them? Do you have any experience with them?

Ryan
Ryan,

$350 for the power head alone, no carb, no lower. Gary Prusse at G&M Models builds them. He can be reached at (630) 279-2451. Yes, I do have one on my 34" WOF.. Still breaking in the motor, taking it easy for now. Trying to get a bounce condition worked out. Might move the motor over to a Aerotech hull to see if that'll work.

As for the Rossi, check with Jul (wave waker on RCU). He has a Rossi 7.5 OB. From what I've heard about Rossi's are they are set to run alcohol, not nitro. One other item with Jul's is that there was a missing rubber seal on the water jacket. This could be the cause of some of the problems getting that motor to work. I've also heard from other racers, on the Rossi's 3.5, that the carb is junk. Replace it with a K&B or other and it'll work fine.
Old 08-01-2006, 10:15 PM
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Default RE: Looking for a 7.5 OB

I was looking at a tunnel that sold a while ago on another forum/site with a Nelsen 7.5. I really like the look of the block but it is a bit out of my price range. What are your speed predictions for the Nelsen?

Ryan
Old 08-02-2006, 02:17 AM
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Default RE: Looking for a 7.5 OB


ORIGINAL: ryan_t888

I was looking at a tunnel that sold a while ago on another forum/site with a Nelsen 7.5. I really like the look of the block but it is a bit out of my price range. What are your speed predictions for the Nelsen?

Ryan
High 50's plus..
Old 08-02-2006, 09:58 PM
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Default RE: Looking for a 7.5 OB

isaw OB NUT's Nelson engine and how it performed, this is for a real serious boater, kinda intimidating for a newbie though....lot of power on it, good lookin powerhead..

here's a pics of rossi,,,ready to go this weekend...
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Old 08-03-2006, 11:41 AM
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Default RE: Looking for a 7.5 OB

Does anyone know a link to the Nelson motor or any info`s about it ?

By the way the rossi looks great [8D]
So i'm looking for a detail report after the weekend wave waker
Old 08-03-2006, 11:53 AM
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Default RE: Looking for a 7.5 OB

http://www.nitrowatersports.com/vision_tech_engines.htm .
Old 08-03-2006, 02:38 PM
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Default RE: Looking for a 7.5 OB

Does Brian ever update that site. Looks like all the information is very old.

Ryan
Old 08-03-2006, 09:03 PM
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Default RE: Looking for a 7.5 OB

That is Brian Nelsen, not NELSON.. They are two different motors. Nitro Water Sports is still working on their 7.5 OB.

As for the site, yea, it's a few years old. There are no sites for the Nelson motor..
Old 08-03-2006, 10:45 PM
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Default RE: Looking for a 7.5 OB

Oops![X(]
Old 08-05-2006, 05:58 PM
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Default RE: Looking for a 7.5 OB


ORIGINAL: ob nut
Nitro Water Sports is still working on their 7.5 OB.
When will they have their OB ready? Will it be more superior compared with the Nelson?

Ryan

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