HST Setup

I just bought a 91 HST with a 1996 Mercury 2.5 Drag.  The boat is beautiful and was raced in Wichita Kansas back in the early 90's.  It has a blueprinted bottom and rails along the tunnels that go forward about 48"'s.  It has a standard non-adjustable 6" setback and then a hydraulic 5" jackplate.  The engine is in great shape and I had CDI electronics rebuild the ECU module and install an off shore chip instead of Drag? Good or bad. I also replaced voltage regulator and stator with aftermarket parts.  I think the engine cranks out around 280?  The lower unit is stock factory w/ low water pickup and large V-6 gear case.   I have an assortment of props, 24p chopper, 30p chopper, 27p cleaver and a 27p 4 blade pass thru michigan wheel rapture.  The boat loves the 24p and it is very quick, but blows out at the hole shot.  Also after reading your articles on drive height, I think I've been running to high.  I seem to have in excess of 20% slip from info with the calculators.  I was turning 7200 rpm and going about 70 mph w/ 420 lbs of passengers (Dad and I).  I then went to the 30p chopper and this was today, I was turning 5800rpm and going 68mph by myself, I think better.  The rooster tail is probably 150 yds long-bad?   He keeps telling me to trim it out, but I think that I'm not accomplishing anything by this.  The 30p chopper is better out of the hole, but still spins out.  Once it hooks up the acceleration is good, but not as quick as the 24p.  Have you ever ran a cleaver on this boat?  I need to take this one in the have a machine shop turn the hub on a lathe to make it work, is it worth it or stick with the choppers.  The michigan wheel has no hole shot which I thought was weird, that engine should turn it, and the boat started to chine walk around 65, this never happens with the chopper.  Any info on how this boat handles and gear case height would be appreciated.  I've enjoyed ready all your articles posted.  Also, any way to register with your Hydrostream.org website.  My Dad used to sell hydrostreams in the late 70's up in Aberdeen South Dakota , Lefty's Marine. Thanks for your advice.

Eric Wagner

 

Eric,

The chip is a good move as the 96 drag engines were nothing more than a stock 260 with 26 cc heads. I would imagine yours has a pump gas head or it would be in pieces by now. Stick with Chopper style props and lower the motor until the steering torque goes away. You will probably be just below the pad (bottom of the center pad) with the prop shaft centerline. By going down on the transom, running the 24 chopper at 7500 plus rpm, and getting the rooster tail down you should be in the 90ís pretty easy. The rooster is giving it away that you are too high.

Randy

 

 

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

 

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