Prop options for a 1971 johnson 40hp

[77kingfisher]

What prop options (as in new props still available on a budget) are out there for my 40EL71G and what pitch options should I consider for a 16 foot kingfisher weighing in a around 700 lb with people in it.

 

[ondarvr]

Check here on iboats for the props available. As for what it may need....there's no way to tell until you run it and check the speed with a GPS and use a good tach to record the RPMs.

Is there a prop on it now?

 

[82rude]

Right here on iboats they show 2 props still available.Only 2 pitches 11 1/2 and 12,.Non through hub exhaust pin drive.

 

[jimmbo]

I would go with the 11 1/2. On our 14 ft with a 1963 40hp we used a 12 in most of the time, and occasionally an 11 1/2.

 

[77kingfisher]

Well according to my service manuals it came std. with 10.5x13. I have 2 identical props no idea what pitch. One needs a new hub and re pitch without question (OEM??) the other is a Michigan 3 blade (Good?). So I think ill try the "good one" and then have one or both gone over. Is a 13 without question too steep?

 

[Sea Rider]

Impossible to tell, must install a tach to check max wot rpm achieved as usually loaded on flat calm water. Each OB has a min-max wot rpm range in which need to work. If without a tach won't see the light at the end of the tunnel any time soon...

Happy Boating

 

[jimmbo]

Look at the prop carefully. The dia and pitch should be on there. Most of the time it will be on the end of the hub by the drive pin, or on the edge of the opposite end of the hub. Some of the OMC props for that engine had the info on one of the prop blades

 

[77kingfisher]

Cant clearly read any numbers on the props but lord only knows at this point. And I do have a tach so once im finally in the water ill have to read it and see if im in my 4-5k range.

 

[Sea Rider]

If with no clue about prop diam and pitch, take it to a prop shop and have it measured. That's your trial prop, once wot rpm are known can go for a prop maximization to a less pitch if in need to pull wot revs middle to max wot range as currently loaded.

Happy Boating

 

[77kingfisher]

If with no clue about prop diam and pitch, take it to a prop shop and have it measured. That's your trial prop, once wot rpm are known can go for a prop maximization to a less pitch if in need to pull wot revs middle to max wot range as currently loaded.

Happy Boating

Ok yes that sounds like a grate idea. Now im wondering if there are any around my local area.