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Hoocher
09-18-2006, 11:35 PM
I just ordered a new prop from Delta Propellor Co. and they recommended a 13x13 LH 1" Ambush 4 propellor, which I received today. Much to my dismay, the old prop on my 85 S&S is a 14x18 LH 1-1/8" Nibral cupped propellor. The Mastercraft owners manual just mentions it is 13x13 stock, and does not state shaft size. I contacted several propellor companies and they all recommended a 1" shaft. Does anyone else have an old S&S with a 1" shaft?

88 PS190
09-18-2006, 11:48 PM
do you have a powerslot transmission?

open the engine and look for velvet drive 1.5:1 ratio.

if so its a different prop than a 13X13 LH... thought they were all 1" shaft but icbw

JEREMY79
09-18-2006, 11:53 PM
mine is a 1" shaft. I think the powerslots have the bigger prop

Hoocher
09-19-2006, 12:14 AM
I believe I have a 1:1 ratio model 71C velvet drive.

88 PS190
09-19-2006, 12:24 AM
i'd give that a check... only powerslots had the 14" unless someone upsized the whole shaft and prop... or something, that's odd.

PendO
09-19-2006, 12:44 AM
man, there is no way a 1985 1:1 tranny could spin an 18 pitch prop up to 4000+ rpms ... on the bright side, sounds like you just found out you have a boat with Powerslot, which adds value to the boat:)

Prior to replacing your prop, what was the Max RPM's you could get on the boat?

PendO
09-19-2006, 12:59 AM
from a different thread (http://www.tmcowners.com/teamtalk/showthread.php?p=161652#post161652):

You have the 1:1 tranny, however you also likely have the slotted hull configuration for the drive option. The 8th and 9th space from the engine serial number will read 10 for the 1:1 and 15 for the 1.5:1.

Check the Vin# on your boat ... I suppose it is also possible that along the way someone has replaced the tranny with a 1.5:1 and changed out the shaft size, so, if you look at the vin you can tell what tranny was OEM

Hoocher
09-19-2006, 01:04 AM
You were correct it had the 1.52:1 velvet drive with the larger 14x18 prop. What were the advantages of this transmission? Any recommendations for prop size for wakeboarding?

Hoocher
09-19-2006, 01:08 AM
I never maxed out the speed/rpm, since there was vibration and the lake I go to is very rough most of the time. The owners manual for the 85 doesn't have much info for this type of stuff?

PendO
09-19-2006, 01:20 AM
I never maxed out the speed/rpm, since there was vibration and the lake I go to is very rough most of the time. The owners manual for the 85 doesn't have much info for this type of stuff?

Consider yourself luck to have the PS tranny and not even know it :)

Take a look at Acme (http://www.acmemarine.com/)or OJ Props (http://www.ojprops.com) ... you can contact these manf. directly if you want, OJ is the current OEM prop supplier to MC.

They can likely answer your questions much better than I, but if I were you (just wakebaording) I would want to try out a CNC'd 18 pitch prop and a prop one pitch size smaller.

The advantage of a smaller pitched prop is even better holeshot, but you do not want to risk overrevving your engine.

Lots of the new boats (I think all the MC's) come with new OEM 4 blad props ... typically having a 4 blade is like having wider tires, giving you more traction off the line, however ... like a mountain bike and a road bike (skinny tires are faster) typically the 3 blades in the same pitch are faster ... in recent years companies have come up with more precise manf. techniques and there are 3 blades that push as much water as 4 blades, but still have the top speed advantage.

Carefull about going to a stainless steel prop if you are ever at risk of hitting something as the SS will not bend and the damage will go to more expensive parts (shaft on up) ... whereas the nibral will bend easier and hopefully prevent damage up the shaft.

PendO
09-19-2006, 01:25 AM
when you wakeboard behind the boat do you have much ballast in it? If you are running with a lot of water ballast a smaller pitch prop would be nice?

88 PS190
09-19-2006, 01:25 AM
Pendo has it, for a few years 4 blades were all the rage, then w/ the fully CNC'd prop the 3 blades w/ more surface started out performing the 4 blades.

Now in general for slalom people run a 3, though some like the wake better behind a 4 blader.

4 blades i believe hook up better, important moving a ton of ballast onto plane.

PendO
09-19-2006, 01:37 AM
when you put a new prop on ... if you still have vibration you will want to have the shaft alignment checked ... if your current prop is dinged it is also possible that the shaft is not completely aligned ... however, I am putting the cart ahead of the horse, but just wanted to throw that out there.

Hoocher
09-19-2006, 01:45 AM
I appreciate the help, I completely thought I had the 1:1 trans! I was going to check the runout on the shaft to make sure it is not out of round. Anyone know of the specification for the shaft for being in alignment? Is the Powerslot just a heavier duty trans?

Hoocher
09-19-2006, 01:48 AM
I usually just have about 600# ballast, but might increase that next year as I get better.

88 PS190
09-19-2006, 02:01 AM
a powerslot is a standard transmission, with a gear reduction on the end of it.

That allows the boat to swing a bigger propellor at a slower speed as opposed to a smaller prop at higherspeed.

Gives the boat better acceleration (important for slalom on short set ups) and allowed boats to hold their speed better to keep times on the slalom course w/ big strong skiers.

The 1.5:1 for wakeboarding would allow you to get ballast moving w/ less strain on the engine.

Only disadvantage, potentially lower top speed, and lower fuel econ at top speed.

Its like using a lower gear on a bike... just you can't shift it up.

Brn85ss
09-19-2006, 12:28 PM
The stock OJ 3 blade or an Acme #801 is your only 3 blade prop options.Lots of 4 blade props for the reduction trans.