prop calulator
 

I need to change my prop,I have 1977 v20 steplift with a GM inline six cylinder 165hp,omc stern drive.Can anybody advise me on how to work out measurments of my existing prop.[I believe it is the standard 3 blade original]
Thanks...genesis 08 going nowhere,

Regards Brian..........

Brian, a couple of the guys posted these links a while back. They may be a help to you. If not, hang on as I'm sure the guys will have plenty of good advice for you.

Ferm posted this one:

http://www.rbbi.com/folders/prop/propcalc.htm

BS posted this one:

http://continuouswave.com/cgi-bin/propcalc.pl

Steve

prop prob
 

Thanks,B



I will wait and see what happens.Is there anybody out there with the same set up as I have,inline6,omc stern drive etc?

Brian

14 x 17 was the first prop, it went well and top out out good, but was a dog out the hole.
2nd was a 15 x 15 1/4 It got me up and out the hole fast!! Great when I had a load, but would lose a little on the top end.

Seeing a 70 something V with a 165 I/O had a top end of 30 MPH + or - It was not a big deal to me.

prop
 

Thanks mac,

At least that gives me a starting point,I know the diameter is 14 so I will takeit from there.The prop has no splines it uses a pin to secure thru the shaft,that might help a bit further with identification!

Regartds Brian..........

Spareparts deals with alot of I/Os I think, ask him.

prop prob
 

Thanks Bradford,

I will check him out!

Regards Brian......

that sounds like an electra shift stringer drive, its getting scary around here lately. I thought all those stringer drives would have died off by now, but now there are two on this site. My bad attitude towards OMC can be directed squarly at their attemp to create a decent outdrive.

I can't remember what the gear ratio was, but most of those old drives used 15 p wheels, check with some prop shops, they will probably have several laying around for sale cheap. Start with the 15, carry a shop tach and see what that engine turns, they don't need a lot of rpm, 4200 to 4600 at WOT should be about right. Make sure you don't tilt that drive while under load, it will kill your ball gears real quick. If you can take a 17 with you as well, if you can spin it 4200-4400 you'll be ok if you can live with the holeshot

We used to call those "white elephants" I had one that ran a 14X14 prop

Perhaps this will help

http://www.wellcraftv20.com/gallery/...1_G_001?full=1