Prop question

[grousehunter 61]

I have a 35 twin evenrude ( 1958 ) the bottom end seized and I was looking at $360 to repair it. Just by luck I drove by an auction barn and sitting out side was a 1957-? Johnson 30 hp, they sold it to me for $20.00 including a fuel tank with duel lines. I pulled both bottoms off the motors and the Johnson fit just like it was made for it. Now for the question, the Johnson has a 10x10 prop on it, it looks brand new. It has bigger blades and more pitch then the one that I had been running on the Evenrude, which is unmarked. With more pitch and larger blades, what will this do for or against the evenrude. I run this boat at high altitudes, over 5,000 feet. The boat is a 1958 Crestliner, 14 ft commodore. For those wondering why I didn't use the Johnson, it is seized on the top end.

 

[metriccrescentwrench]

Re: Prop question

You probably don't want the increase in pitch with that new prop, it's likely going to make your engine lug and you'll take longer to accelerate (assuming the engine was running well with the old prop) - lugging 2 stroke engines by overpropping is bad for their health, leads to carbon buildup and an early death. Maybe try it and see what you think, but I'd guess you won't like it (especially not with the high altitude).

 

[steelespike]

Re: Prop question

As you may know a good twin hose tank is worth some bucks also the connector is like gold.
You lose 3% per 1000 feet under ideal conditions.You should have a tach(tinytach is reasonable
and easy to install).With a gps for speed and the rpm you can tell if the motor is running within its rated rpm range. A prop shop can tell what your old prop is.A 10 X 10 Is the smallest available here at iboats with a 13 1/2 being the biggest.So your 10 X 10 may be just right.
Run the motor with the new prop to get base line numbers then the prop shop may be able to repitch the new prop.

 

[grousehunter 61]

Re: Prop question

Thanks guys, as soon as the ice is off the lake I will try it out. Your right a tach would be a good thing, I have nether tach or speedometer.

 

[grousehunter 61]

Re: Prop question

While on the subject, just what does 10x10 mean in prop language

 

[steelespike]

Re: Prop question

Prop size is in inches diameter X pitch.Pitch is the key number.Diameter generally follows and not generally directly considered.Lower number pitch more power higher number less power more speed. Think of lower numbers as like 2nd or 3rd gear and higher like 4th or overdrive.In a boat you have to select one "gear" todo it all unless you change props for specific activities.Some do.