Old OMC Propeller ID

[Paul Moir]

I'm having trouble identifying a prop I've got here, and if anyone can provide assistance, I would really appreciate it. This is an old OMC pin-drive "Big Twin" type prop (25-28-30-33-35-40hp). The numbers on it are:<br /><br />10 3/8 x 1 ... / .. (maddeningly undecipherable due to a casting flaw)<br /><br />Then:<br /><br />302657 or<br />302651 Or something like that. All I really see is<br />3U2oo/<br />I'm pretty certain about the '302', less certain about the '65', and I can't tell if the last digit is a 1 or a 7. It came in a box containing three 10 3/8 x 12" props, but it looks different from them as it has much more blade area along the trailing edge. It curves out rather than simply being cut off straight. Otherwise, the pitch seems similar.<br />I know it's not much to go on, but I've tried searching out various permutations of the numbers above. I suspect the number was long ago superseded. Thank you for your time and expertise!

 

[Tracy Coleman]

Re: Old OMC Propeller ID

Looking at the 2000 OMC P and A book shows the following (1951-1976) pn 376738 11 X 9, 385955 10 3/4 X 11, 380637 10 1/2 X 12, 384460 10 1/2 X 13,<br />378571 10 3/8 X 14.<br />Backfire

 

[walleyehed]

Re: Old OMC Propeller ID

Paul. I've got some books at the shop for P&A for those years....well, early 50's on. I'll go take a look and get back to ya.

 

[Paul Moir]

Re: Old OMC Propeller ID

Thanks Backfire and Walleyehed.<br /><br />Backfire, your post got me thinking about this - all the new props (and the three other props from the box) are even pitch fractions (9, 11, 12, 13 and 14 inch), but I had seen props in the old early 60's catalogs calling out 12-1/2, 11-1/2 and 13-1/4(?) pitchs. When I looked them up I found a bunch of them had (claimed) 10-3/8" diameters.<br /><br />So I set up a crude jig here in an attempt to measure the pitch and I seem to be getting a 12.5" pitch for it. Now I might be doing this the wrong way and there's a fair bit of error in the jig but the 12" props seem to measure out as 12.0".<br /><br />I know digging through parts books is a pain in the neck, but it would be a real help to me if you could confirm that number, Walleyehed. I'm not very certain at all about my measuring jig!