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Modified Nose Cones amp Motor height

R

roger

Member
" Just picked up another boat

" Just picked up another boat woth a 70 HP Johnson. Motor has a modified nose cone with front water intake. This poses a problem for me in flushing with fresh water. Any ideas where to get an adapter or some other method to connect fresh water.
Also motor is set with centerline of bullet at 2" below keel. When dropping the hammer from a stop she starts to pull up, slips (prop in air) then settles in and winds out to 6500 RPM (modified head). I think the motor might be set too high. Any opinion on this. Boat is a 15ft Checkmate. "
 
" From what I'm told, the

" From what I'm told, the cavitation plate should be level to 1 inch higher than the bottom of the hull. My 1978 Johnson 70 sits about 1/2" higher on my 15' fiberglass. Taking off from the hole is fine as long as I have the motor trimmed down, otherwise I get blowout just like you are experiencing. I've found this setting to give me good nose height when trimmed out on plane, good balance, and decent speed (I achieve about 30mph @ WOT). I'm running a 13 3/4 X 15 stainless prop with everything bone stock.

The 6500RPM sounds pretty even for a modified head, I can get to 6500 too when I get prop blowout but I don't think it's the healthiest thing for my old beast. "
 
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