1973 Merc 1500
The motor in question is on a 17' Checkmate, but
I have not found a Hydrostream here yet in West Michigan. I have done
everything to this motor and it seems to run well. A problem has popped up
with the stator that could be related but it was working earlier as I
tested it when replacing the rectifier. It only runs 50-54mph @5000-5400
with a LaserII 20 or a Merc stock 21@100rpm less and no lift. It depends
on the temps outside as to what it runs. The tach is calibrated, the new
speedo seems to be close or 2-3mph less than other boats. Prop calculators
put the speedo pretty close. I have been told it should do an easy 60mph.
Others have told me Mercury rated them at the head so they are over-rated.
Mercury says use a 23-25 prop for this boat, and run 4800-5800 rpm. It
goes slower with a SS 17 @5700rpm and 48mph. It has 120psi compression +/-
2psi and appears to be in very good condition. The hull is mostly a vee
with small trihull sides and no pad. The transom is 20" but the motor
has been raised 2" so the cav plate is about 1-2" above the
bottom. I have most of the interior removed and the as-new weight was
under 1000lbs. I have tried larger and smaller props with less success.
What should this motor do? Any help would be great as this is the second
summer on this.
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.
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