25 OMC 24mph on 10X13 @5200rpm- Suggested prop?

[thecadman99]

I really need a new prop on my 25- the stock one is pretty chewed up and getting out of balance.

Took the little sea nymph 15' aluminum out yesterday, loaded with 2 people and fishing gear.
It has a 92 Johnson 25 on it. Came on plane a little sluggish, took about 10 seconds to plane. Tach showed 5200 rpms at 24 GPS mph.
It has the factory 10X13 prop on it now.

I'm thinking of getting the Solas Amita 10X13. (its actually a little larger diameter at 10-1/8)

What I'm worried about is the 30hp carb I'll be putting on it this week. I'm thinking if I get a little more HP it may be able to push the Amita up to 5400 or so rpms and maybe give me a little more initial torque.

Would anyone recommend just dropping to a 10X12 instead?

 

[Mi duckdown]

Over thinking. Rebuild the original prop and run. Forget about the 30 hp carb. MY .02 .???
(I really need a new prop on my 25- the stock one is pretty chewed up and getting out of balance.)

 

[steelespike]

If you insist on the 30 hp carb put it on ,get set up best you can and do a lightly loaded test run get us the rpm and gps speed.
Then we can tell if and what prop to try.

 

[thecadman99]

Ok, just got the carb in. I'm going to give it a good cleaning, bolt it up, crank it up, and see how it goes. If it will quit raining here in Va. for JUST ONE DAY lol.

 

[steelespike]

Ok, just got the carb in. I'm going to give it a good cleaning, bolt it up, crank it up, and see how it goes. If it will quit raining here in Va. for JUST ONE DAY lol.

If it rains enough you could try it in the front yard. lol

 

[jauguston]

My 1991 Factory Service Manual says the 30 hp version of that motor has a maximum recommended operating RPM of 5800. for the 25 its 5500.


Jim

 

[Sea Rider]

Check parts manual, sometimes it's not just a carb swap, you must change reed valve plate assembly + both RVP gaskets. Larger carb will need larger 30HP reed valve ports to work accordingly. At least on OMC 9.9 & 15, both being 250 CC blocks must do both swaps to have a well converted updated model.

Happy Boating