need prop size

[bubbakat]

can someone tell me what the pitch are on these two props by the number on them.<br /><br />Michigan PJ80<br /><br />This one brand unknown<br />508c

 

[notarealone]

Re: need prop size

Need more info. Stainless or aluminum? What size motor/boat did they come from?<br />Inside the hub somewhere you will see 13x19 or some other numbers. The first number is the diameter and the second is the pitch.

 

[bubbakat]

Re: need prop size

Skeeter thanks for the reply.<br />They are aluminum and they are on a 1987 70 h/p evenrude.<br />There are no other numbers on them this is all there is.<br />If it had the pitch I would know which way I need to go from here. I am gonna upgrade to a ss but want to find out the pitch I already have before spending that much money.<br />Oh well I guess its off to the prop shop for me.

 

[johnjsa]

Re: need prop size

Bubbakat, I'm in the same shape you are in. I have the same 2 props you have, PJ80 & 508C & don't know what pitch, someone said probably a 17. I too am going to a stainless prop for my 1977 JOhnson 70 HP & I have a another guy doing some research for me, if I find out anything I'll let you know.

 

[jtexas]

Re: need prop size

you can get a rough measure of the pitch as:<br />circumference x slope,<br />where circumference = diameter x pi, and<br />slope = blade depth ÷ width.<br /><br />It's easiest to measure the depth and width at the hub - in the picture below I drew a yellow line to represent the depth measurement and the green line is the width.<br /><br />If you measure at the hub, then use the hub diameter in the formula.<br /><br />The actual prop diameter is twice the distance from blade tip to center of hub. But it's harder to measure width and depth at the tip.<br /><br />

<br /><br />for example, my '79 rude 70 has the standard 13.75 x 17 prop - I measured the the depth/width as approx 4/3, and the O.D. of the hub is about 4, so 4 x pi x 4/3 = 16.8<br /><br />that should be clear as mud...

 

[bubbakat]

Re: need prop size

Thanks j that will help.

 

[walleyehed]

Re: need prop size

bubbakat, email me....<br />ktsander@st-tel.net

 

[johnjsa]

Re: need prop size

Bubbkat, if you find out what your props are, would you let me know. jmlowe@glasgow-ky.com.

 

[johnjsa]

Re: need prop size

Bubbakat, I was told the Michigan PJ80 prop is 14 X 15. Not sure about the 508C.

 

[outfishing13]

Re: need prop size

I have the same prop and was wondering the same thing. I did a search an the web and found this site. http://www.piranha.com/prop_search.php The Michigan PJ80 is a 13 3/4 X 15. I also have a Michigan PJ89 C which is a 13 3/4 X 15 with a cup. I get about 10% better spead on the top end with the cupped prop but it is a little harder coming out of the hole.