prop for old OMC

[robot]

are there any manufacturers of props for a '57 rje-19 35HP johnson(javelin)? I don't believe I have the original prop (it's brass, I've been told the orig. prop was aluminum).

I would like to get more top end out of the motor, and a prop is probably any easy way to do this.

 

[walleyehed]

Re: prop for old OMC

Take a look here, robot....

http://www.iboats.com/mall/propfind...power=35&year=1957&rotation=Standard&x=37&y=9

Post back with your current pitch, material and blade count....we'll see if we can help ya get a bit more speed.

 

[robot]

Re: prop for old OMC

i dont think that link is what i need. my prop looks like this one:

but it's brass(3 blades). I don't know the pitch.

 

[walleyehed]

Re: prop for old OMC

Same prop... the pictures listed with the link are generic...the info says 13 spline, pin drive....thats what you have.
The prop you would order would look like what you have, just aluminum.....better than brass anyway.

 

[robot]

Re: prop for old OMC

today is my lucky day. I thought I might have the factory prop.

I do.

It's in a michigan wheel box(the michigan wheel prop is on the motor now), along with the michigan wheel service manual. It's very difficult to read the original box.. I think the specs for the prop on the boat now are:

michigan wheel part # is SMC52A
the dia/pitch is 10 1/2 x 11
the metal is bronze.
the price is $20
the motor/model is 22-25-28 -30-35 hp john/evin/gale
the recommendations are: offshore boats - small cruisers- louds?? - skis

here's a pic of the factory prop:

the michigan wheel page recommends these:

10-3/8 X 12-1/2
10-1/2 X 12
10-3/8 X 11-1/2
10-1/2 X 10

so the current prop on the boat is: 10 1/2 -11
it looks like my options are:

10-1/2 X 10
10-1/2 X 12


or can i put a 10-3/8 prop on this?

what is the factory pitch? what will increasing/decreasing the pitch do?

 

[walleyehed]

Re: prop for old OMC

The new design props are likely a bit more efficient...don't worry about diameter...that's all taken into account in the design.
Decreasing pitch will slow down trolling speed slightly, give you a quicker hole-shot, carry a load better, allow a bit higher RPM but may drop a mph or so on top-end.
Increasing pitch will slow the hole-shot, won't plane out very quickly with any load, may be a mph or so faster, but may possibly lower the RPM enough to lug the engine and create very high combustion temps that lead to other problems.
The 10-1/2X11.5P is probably the highest I would go unless I had a tach telling me I was extremely over-reving the engine.

 

[steelespike]

Re: prop for old OMC

Maybe I'm missing something but I don't see any indication of what you are pushing.Max factory speed rating is 33+ mph.Obviously this is factory equiped on a normal runabout.
If you are sure the motor is in good condition and properly tuned there are other things to try for more speed before going to a prop.Check where the antivent plate is. Should be at least even with the bottom of the boat.Also if you can raise the motor 1 inch without ventilation problems you could gain 2 to 3 mph.

 

[walleyehed]

Re: prop for old OMC

I do agree with the above post, but sooner or later we're gonna need to locate a prop that in some cases is NLA, and that is my concern at this point. Raising the engine, yes...problem is, these prop styles are not capable of running much higher than "On the transom".

 

[jimmbo]

Re: prop for old OMC

The factory prop, as stated in the 1957 owners manual, was 10 3/8 X 13 1/4. I happen to have one too. Like new, never been rebuilt, just the paint worn off the tips.

 

[Always Broke]

Re: prop for old OMC

I don’t know what anybody else got out of their old 35’s but I have ’59 soon to be retired because of the boat it is on is shot. I’ve shimmed up the motor on the transom with 1X2’s until it started sucking air in the turns, trimmed it out just right and never got over 26 GPS, MPH out of an 11’ fiberglass semi-V boat. I wouldn’t expect to much from these old timers I’ve had 3 on various boats and never did much better.

 

[steelespike]

Re: prop for old OMC

The factory rating is 33+.No doubt less in real life on a everyday type boat.The 18 hp.Is rated at 27.
I had a new 61 18 on a big 15 ft. over 6 ft wide Chriscraft kit boat with full runabout front, center and rear decks.With tiller steering it ran 23 mph day in and day out and once approached 26 down wind under just the right conditions.Sure it was indicated on the old style speedo but I think the day in day out performance gives
an idea of what the possibilities might be with larger motors.
By the way I have a Michigan bronze wheel that sure looks like the ones here. SMC 655 No indication of the pitch or what it might fit.

 

[steelespike]

Re: prop for old OMC

I do agree with the above post, but sooner or later we're gonna need to locate a prop that in some cases is NLA, and that is my concern at this point. Raising the engine, yes...problem is, these prop styles are not capable of running much higher than "On the transom".

I agree but::
I think how much you can raise the motor depends on
the actual transom height and of course the design of the bottom of the boat.
Where is chinewalker when you need him?I'm sure he and his father have messed with these motors at some point in their racing careers.Maybe knows some tricks to improve performance.He may have a line on what props are available possibly even in his inventory.

 

[walleyehed]

Re: prop for old OMC

What I was trying to say, is the technology of the props available for this application will limit the engine heigth considerably. A special-built prop "for" this application with added features, is a different story.

 

[steelespike]

Re: prop for old OMC

I fully agree but it is also possible the motor could need to be raised an inch or so just to reach its best performance height.
What kind of boat are we dealing with anyway?
Unless it is a real tub it would seem at 11 inches we're
running a pretty light pitch.Maybe try the factory prop
if it is a 12. Surely if it is too much it will be obvious