no markings on prop hello people

[jasonoberry352]

ok 17ft. sport craft cc w/ 1989 merc 70.only 2950 rpm @ wot 27 mph on gps.usually 4 people on board. no markings on prop 3 BLADE CHEAP ALUM. I want rpms to run around 5000 when i need it to . It already sucks @ hole shot about 6 TO 7 seconds to get on plain.how do i know how much to change the pitch with no starting point ????

 

[dutchdog]

Re: no markings on prop hello people

If there is a propshop near you they can tell you what pitch you have. Sounds like you have way to much pitch. The prop shop should also tell you what prop you need. The shop here will let you try different props to see what best fits for what you want.

 

[sethjon]

Re: no markings on prop hello people

The prop should have it on the barrel part engraved in. It has to be there. I can't tell you what to get since you don't know what you have, but I wouldn't drop more 2".

 

[steelespike]

Re: no markings on prop hello people

Numbers may be under the prop nut,I have a feeling you have more going on than prop selection.Assuming everything is accurate You have to make up 2100 rpm
at about 200 per inch of pitch thats over 10" If the prop was way,way too big at say 23" you would be at 13" pitch Close to the size needed for a pontoon boat.
Hopefully you have a cylinder that is not firing or perhaps a timing issue.Maybe the throttle isn't opening all the way.?