1955 Johnson 25 horse prop pitch

[55Crestliner]

The only number my prop has is 302651. It is way down inside the hub. There are no numbers where the nut goes, and no numbers on the blades. This prop is in VERY good condition, still has most of it's original green color. There's no indication it was repainted. The Johnson shop has no number like that.<br /><br />I would love to know what pitch this prop is, so when I test it I know what size to buy if it's wrong for the boat - or if it gets damaged.<br /><br />I would just go to the prop shop, but their guage seemed very inaccurate - it said their brand new prop was 2 inches different than it's markings.

 

[Paul Moir]

Re: 1955 Johnson 25 horse prop pitch

I have prop marked 302651 in my hand. It's a 12.5 pitch x 10 3/8 diam prop, which was the "standard" prop that came on your engine. If that 25hp was very well looked after it's possible it's the original prop.<br />I think the 302651 might actually be a casting number, and that the real part number for the prop is 277581.<br /><br />Are you planning on mounting this on your beautiful Crestliner? I'll be interested to hear the results.

 

[55Crestliner]

Re: 1955 Johnson 25 horse prop pitch

That's great! THanks so much. <br /><br />I'm wondering what a 15.5 pitch would do on this boat (yes, the Crestliner). There's one available.<br /><br />Won't know till I get it on the boat and see what its RPM's are of course.

 

[Paul Moir]

Re: 1955 Johnson 25 horse prop pitch

You can buy new props 10" - 14" from Iboats that fit your 25hp.<br />You can buy new BRP props from your local Johnson or Evinrude dealer 11" - 14".<br /><br />The used market provides a little wider choice. Frequently old 2-blade Michigan wheel speed props turn up. But the brass ones are really hard on the lower unit gears so avoid them. These propellers are everywhere because they were used on all the Big Twins 25-40hp.

 

[55Crestliner]

Re: 1955 Johnson 25 horse prop pitch

The original prop mentioned above was turning 4410 rpm. I bought a brand new Michigan Wheel prop, sized at 14" pitch. This prop didn't bring the rpm's down much at all. It's now turning 4330 or so. Seems that a 1 1/2 inch increase would bring it down a bit more than that, wouldn't it?<br /><br />With the old prop the boat was seeing 27mph (speedo, not GPS). With this new prop, it's seeing 28, 29 if I sit in back (but that doesn't really count, since I only sit there to tune it.)<br /><br />I really thought 1.5 inches more pitch would see 30mph. What's going on here? Does the Michigan Wheel prop have less pitch than OMC? This seemed to be the case with my 18 horse's props.