|
Originally Posted by bobkatz
(Post 4117279)
If you change the angle of the extension box versus transom, the motor will need to be moved also. The engine coupler must be parallel to the extension box input flange or you will get a vibration in the drive line. Possibly grenade a universal joint... The motor and boxes can be offset, just keep in mind the driveshaft angle will get very steep if you tilt the motor and box at the same time. I was told 10 degrees was the max on driveshaft angles, I have seen more but that was the recommendation to me.
I had to cut my extension boxes apart and mill the flanges to match my transom then weld everything back together to get the angles correct. |
5 blade, 4 blade, 2" spacers... none of those made any real difference until I got a set of props that had over .100 in cup.
cupping grabs water and prevents the burnout. |
I've been preaching props for a couple years now, in regards to the older SSM stuff. I've tried ALOT of props on my boat with SSM IV's in the past 4 years.
18x28 three blade mercs. Planed decent. 4000RPM and came over fairly soon. 16 7/8x27 four blade mercs. Planed AWESOME. 2800RPM and layed right over like a ski boat. 17x29 Four Blade mercs. 5000RPM and have a beer. 1/2 mile to lay over. 16.75 x 28 four blade mercs with rounded ears. Planed awesome. 3000RPM layed right over like ski boat. 16.5 x29 Four blades mercs. Simply wouldnt plane at all. Total fail. 16.5 x 28 five blades. Planed awesome. 2800RPM layed right over. 17.5x32 3 blade hoss round ears. 3800RPM, took a while, but decent. So, I've tried 7 sets of props on my boat. You know what I learned, not a fuking thing. What I mean by that, is with these old SSM mercury props, on these #4 and #5 drives, nothing makes sense. Textbook says, more blades, more diameter,spacers, better planing. In the real world, that wasnt always the case. These old props, are nothing like a bravo style prop. They differ so much from pitch, to blade area, to cupping, and so on. I gave up on what the textbook stuff told me, and bought and sold alot of props trying to find a good set. Ive had several of these sets of props scanned on a prop scan machine. The common denominator that the good planing props had, was a high cupping amount. the bad planing amount, a low cupping amount. Some of the props were so far off in blade to blade pitch it was nuts. Thats just planing talk, not even getting into cruise, speed, and handling. My advice, before you go chasing ghosts, try a GOOD set of props. They are hard to find these days without going with a new set of CNC mercurys or Herings. Much of the old SSM 15* cleavers have been molested quite a bit. |
Ive been told I`ll never get on plane with 4 blades, WRONG!
The horizontal numbers at the right (.100 .105 ..etc ..) thats the cup. This props works great! Most of the other props that I`ve tried (even 5 blades) had cuppping in the .040 range and those would not even get on plane at all . http://33outlaw.zenfolio.com/img/s2/...63030030-3.jpg |
Originally Posted by ICDEDPPL
(Post 4169867)
Ive been told I`ll never get on plane with 4 blades, WRONG!
The horizontal numbers at the right (.100 .105 ..etc ..) thats the cup. This props works great! Most of the other props that I`ve tried (even 5 blades) had cuppping in the .040 range and those would not even get on plane at all . http://33outlaw.zenfolio.com/img/s2/...63030030-3.jpg |
thats what I meant to say lol
|
| All times are GMT -5. The time now is 05:06 PM. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.