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Arizona Hotboater

How much setback on a Euro, 2.5 carb?

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The Hi speed porpoise problem I have read so much about showed its ugly face.  Mid 80's the boat will porpoise badly.  I thought the Bobs jack plate I had would prevent that from happening.  Its a 5.5" manual type.  Do I need more setback to get rid of the porpoise?  I was running fully loaded.  2 anchors, nearly full fuel tank, hand tools, cooler, etc...  I forgot to bring my GPS but the Gaffrig said 83 or so.  I think I was going faster because I didnt have the porpoise last time I ran it and I hit 83 on GPS.  (That was when I had a water  leak and was running on 5 cylinders.)

My Yamaha drag excelerated great and had very little steering torque but the back end of the boat was very "flighty" and the steering felt weird.  When I let off the gas there was no steering for a second or 2.  The 30 chopper didnt show the steering problem but the steering torque was triple that of the Yamaha. The stern didnt feel flighty at all but the porpoise was annoying.  

What do you Euro owners suggest?

Thanks in advance,

AZH

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Sounds like where I was 3 years ago when I purchased mine. My suggestion is put as much as that weight to the rear of the boat because what I think is going on it just trying to air out and can't break loose from the water. You might want to try this, bring the STV up to about 50 and nail the throttle with the trim slightly more positive than the best trim setting for top end, and hold on.  Right about 75 it will start to porpoise for a few bounces and be gone just over 80. As soon as you feel the front coming back down trim in just to about even or slightly positive. I have a Stainless Marine mechanical trim which is set as "4" being no trim. When I make a run it starts out at 4 3/4 until I break 80 and then trim back to 4 1/4 or 4. The faster you acelerate the faster it get over the hump and up on the air.  The Merc 1 inch intake spacer helps by in that the engine will rev faster. Yes, setback(5.5) did help my Euro getting past the porpoise..

First of all I don't like the chopper(RE3 & SRX-DAH) because of the steering torque. Also it did feel like the back of the boat was very loose. The best for me are the Merc ET and lab cleaver. Another prop that worked very well was a Hoss Triton 14x28 especially with 2 big guys. If your going out with a big load you might want to try a lower pitch cleaver and let the engine rev for for top end runs. My opinion with the extra weight it easier to drive with the cleaver because the cleaver is helping lift the back of the boat. With my 30 cleaver it runs 107 with 1 person and 98 with 2(240 & 225lbs).

Might also want to try this. After you run up to about 50 or so briefly leave of the gas and turn the steering a few degrees to the left to straighten up the lower unit and then nail it.

Comments from RT from a few years ago

I understand what you are going through. From what I understand, the boat starts to porpoise when it is riding on the center sponson right where is changes from an inverted vee to flat. As for the fix, more trim. Sounds simple but it works in my case, I often power through.

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Hi Mark.

My buddy that has a 2000 Euro with a 1999-280 runs 7-1/2" of setback.

He ran a CMC power jack and added 2" spacers which he says helped.

He usually runs with a load in the boat and was running a Mazco RE-3 29" or a RE-4-28".

He threw a blade off the RE-3 and is thinking of a Lightening ET next.

C-ya.

Randy.

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Thanks for the advice.  I am going to buy the spacers from Bobs tomorrow. I am shipping my heads to JSRE tomorrow also.

A lightning ET is in my future if I can find a deal on a 28 pitch.

That means I'll be selling the 26 Yamaha drag.  It excellerates great but the steering just feels weird.

Later dude,

Marc

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I used to run 7", or a 5 inch plate and 2" built into the SS midsection. I ran a 28 ET at 8500 rpm. I am not a fan of the RE/ RE-4/ SRX, frankly I think they are useless props on the STV, they are tough to drive with them. Merc ET, and Merc cleaver. That Yamaha is way to small in pitch and diamiter to work on that boat. The Yamaha is a good prop for drag racing because it is so inefficiant. Trade that thing. Also I think that you will be a lot happier with an EFI than a carb, the power difference is huge.

RT

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