Prop to pad questions

[Tarheel14]

99 187 Elite 98 175EFI Merc. 25P trophy plus (4blade)

Prop to pad is currently 4". I finally figured out how to adjust the detwiler jackplate.
5600 RPM. Water pressure is about 15psi WOT. Its been close to if not over 20psi before I raised engine.

Getting about 58-60. It did hit 61mph in the morning. Just me and about 1/2 tank.

Im guessing I should go down a bit? Maybe to 3 1/2 inches?

It trims out and rides really good. Not squirelly or anything. I do have a E ladder that drags a tiny bit and a 12" graph that kinda sticks out that causes some drag too.

[SCOTT196]

I would try 3.5 and watch water pressure!

[STLBassBuster]

Go 1/4" at a time, try 3.75" first.

[Tarheel14]

thanks

[MMosher]

What your goal? Max speed? Rough water performance? Overall performance?

[Rick H]

3.5 is best on my 206 w/XB but have nose cone water pick ups.

[tj]

My 1985 dual console 184 Champ, 1997 Mercury 175 EFI & 1997 A45 25P Tempest, 2003 CMC ML-65 (5.5-inch), 3.78 PTP, 65GPS @ 5600, medium load, 3 lead acid batteries. A45 lifts a lot.

[Tarheel14]

I lowered it about a 1/2 inch. Better water pressure. 5400 rpm and about 58mph. I'm really thinking it should at least break 60mph. I'm looking for overall performance. I'm gonna lower it a tad more and see what that does.

[JOE54]

find a 23 TEMPEST a good one not some beat up junk go run it youll probly need to raise it back up some , min w/p in straight run steady 15lbs , prop it for 5900-6000 for best " overall performance " and engine life longevity

[Tarheel14]

What's safe RPM? 5800? Minimum water psi at wot 15+?

[pastormark]

I run a 23 Temp worked by Mark Croxton. 17 psi wp. 58500 rpm's and 61 MPH.

[tj]

I bought a new Mercury 175 EFI in March 1997, from a large TX dealer who had a lot of outboards in stock for repowering.
********************************************
My Mercury Marine Operation & Maintenance Manual (came with my 175 EFI) has Max RPM at Full Throttle info on page 16 chart.

175-2.5 5000-5600 RPM

********************************************
My Mercury Outboards 1997 brochure has Max RPM at Full Throttle info on 3-page chart for all their models.

175-2.5L EFI 5000-5600
175-2.5L carb 5000-5600

[JOE54]

mercury marine recommends proping above recommended rpm range for weather related rpm loss ( engines need to be propped how you would normally use the boat / loaded full wells full fuel all gear and persons in hot summer heat ) you dont want your engine having to struggle to achieve max rpm this will cause excessive wear in 2 stroke engines or most any engine really ,,,, EXAMPLE; if your engine will only turn 5600 light load one person in early spring / cool fall temps its propped wrong ,,,, this info is in factory service manuals

[Tarheel14]

I bought a new Mercury 175 EFI in March 1997, from a large TX dealer who had a lot of outboards in stock for repowering.
********************************************
My Mercury Marine Operation & Maintenance Manual (came with my 175 EFI) has Max RPM at Full Throttle info on page 16 chart.

175-2.5 5000-5600 RPM

********************************************
My Mercury Outboards 1997 brochure has Max RPM at Full Throttle info on 3-page chart for all their models.

175-2.5L EFI 5000-5600
175-2.5L carb 5000-5600

I actually have the owners manual too. I should look it up. Thanks.. LOL... I wonder if I need to change out the hub inside the prop. I have not changed that in years. I can check to see if theres any slippage.

I did go out this past week...but it was pretty windy and choppy so didnt get to run it after I lowered the jackplate a little bit. Thanks for the information.
FWIW..my little champion continues to impress in choppy water. It rides pretty good....Im not saying there are a few times when its like.....ooowww.. but she rides good.