Help needed with Imco shorties
 

I have a 97 35' Fountain that ran 88.5 on gps @5600 rpm's last year. Over the winter I put on Imco -2" lower units on and I am running 88 on gps now at 5600 rmp's. Everything is the same except the lower units. I was told I should except to see a 4-5 mpn increase and personally was excepting to see an honest 3 mph increase.

My question is has anyone else had this problem? If you did what steps did you take to improve your speed? Would adding a 1" spacer possibly give me more top end? Did I possibly raise the X dimension 2 high?

Also, I am told that the boat has a stock X dimension. How would I go about checking my X dimension?

Any info good or bad would be greatly appreaciated. I want to get past that 90 mph mark pretty bad.

Thanks in advance,
T.J.

Re: Help needed with Imco shorties
 

hmm, wierd
i dont know much about this stuff but
i was told by one of the west coast race teams to intall boxes stellings adjustable ones instead of shorties as the props get into cleaner water and will get less slip.. and u would still acheive raising x..
hopefully someone will chime in that has been there done that ..

Re: Help needed with Imco shorties
 

I've been told that extension boxes on the 35 classic won't help because the boat already has a notched transom, but have also been told that adding imco shorties would help the boat pick up 3-4 mph. Boy that's strange that you didn't see any improvement. Maybe the X dimension was already perfect from the factory?

What kind of power are you running to get 88 MPH?

Re: Help needed with Imco shorties
 

I am running 509's, w/990 nickerson carbs, Dart heads and Gill exhuast. These motors were copied from nickerson and he said he dynoed his at 565 hp.

Re: Help needed with Imco shorties
 

try running no trim, neutral trim. when you get the x demension right you need very little trim.

Re: Help needed with Imco shorties
 

Try using a higher pitch prop, less slip.

Re: Help needed with Imco shorties
 

I've tried all different trim heights and I couldn't get any good results. I also have went up to 30 Bravo 1's it ran only 84mph at 5200rpm's. I am currently running 28 labbed hydromotives. Those are the same props that I ran last year.

What should the prop slip be? I just got off of the phone with Imco and they told me it should be 10%. Does that sound right? They also told me to go to 28p bravo's to get more bow lift. They said the hydromotives give the boat way to much stern lift and not enough bow lift. Has anybody else ran into this bow lift problem?

Re: Help needed with Imco shorties
 

Running 88 mph on just 565 HP sounds pretty impressive. The Fountain performance sheet lists the 35 classic with 575's running in the 86mph range, so running 88 with just 15 more hp than the 550 hp 575's isn't bad at all.

http://www.fountainpower.com/Product...ance_sport.htm

Maybe you did have a high X dimension from the factory to begin with and there just wasn't much to be gained by going to the shorties. Other than speed, does the boat handle any different with the shorties, or come on plane any worse/better?

Re: Help needed with Imco shorties
 

i ran 28 hydros on our non step deep x to 5150 and 30 bravos to same got same speed stayed with the hydros as handled better and that was a non step boat.. motors still pullin as hard? i couldnt get a straigt answer out of anyone.. i came to the conclusion its all trial and error and cubik dollars..
i bought the boxes as i was told that wold get me morespeed hell who knowls
someone has to have mesed with it
ask j harris at fountain maybe?

Re: Help needed with Imco shorties
 

Jonas,
What hind of power was in you 35?

Re: Help needed with Imco shorties
 

they were 502's with merlin heads etc as per teaugue est hp was 550.

Re: Help needed with Imco shorties
 

Jonas,
Thanks for the input.

T.J.

Re: Help needed with Imco shorties
 

I would see what happens with some 28" B1's

Re: Help needed with Imco shorties
 

What is your prop height with the shorties?
Trim your drives so the prop shaft centerline is parallel with with the bottom of the boat.
Lay a straight edge on the bottom of the boat directly in front of the drive, extending back towards the drives.
Measure the distance from the bottom of the boat(directly in front of the drive) to the centerline of the propshaft.
What is that distance?
DS

Re: Help needed with Imco shorties
 

JONAS, what was your top end on the '92?

Re: Help needed with Imco shorties
 

low eighteis

Re: Help needed with Imco shorties
 

Toolbox, any progress with those imco shorties? I was thinking about doing a set myself.

Re: Help needed with Imco shorties
 

One of my boats was a 35 lightning and you will NOT get any speed even with extension boxes. The advatage that the shorties have is when your speed is in excess of 90 MPH. At this speed or higher you could expect to see 3-5 MPH over stock length drives. Also keep in mind that fountains have a very high x-demension already, the hulls are pretty much tweeked as much as possible at the factory.