spun at prop question!

[bloodangels]

I was out running my 1970 Mercury 1350 135hp. outboard. It was running great for about 4 hours. I ran it for about 30 mins. at full speed when the rpm's just went through the roof and we stopped moving forward. I immediately shut down the engine. I then tried to rev up the engine again to go forward but if I went faster than an idle speed the boat would not move. I had to idle all the way to the dock. I have psted this message before and everyone I talked to said I spun a prop.
Well, I am a newbe at the repairs so what does that mean? do I have to but a new Prop or can I fix this? I did buy a cd for Mercury engines with all the part numbers on it for the engine and a diagram break down. But I do not see anything that might be called that "spun Prop". Is there some form of rubber in the prop that might have ripped out? If so what can I do from doing this again?
Help!

Phillip Kastrup

[Raceman]

Phillip, "spinning a prop" means the rubber clutch hub in the middle failed. It can be repaired by any quality prop repair facility.

There's nothing you can do to keep it from happening again. Merc even ran the rubber hubs on big block stern drives for years. They're designed to take the shock out of shifting from neutral to a gear, and also absorb some shock when hitting a solid object, both of which protect the gearcase. Merc more recently uses a plastic hub on some of their blades. The spinning you experienced is just an age thing and likely won't ever happen again if you have it re hubbed.


Welcome to Scream and Fly.

[MERCMAN]

you need to have your prop rehubbed at any prop shop. cost? 35 to 60 dollars.

[bloodangels]

thanks guys! Great to belong to a forum that knows how to fix things right!

[bloodangels]

I talked to some local Prop Shop here in Cincinnati adn they said that this was a normal thing that happened with these props during the 70-71 years. He said that the manufacture re designed the hub so it had more rubber to stop it from spinning it out. He said they had two hubs to put back in it. the original or the newer heavier one normally for the 21 degrees and up. My Prop is a 19 degree. I was wanting to know you thoughts on going with the heavier one over the original one?
The cost did vary most boats shops said $75 to $125 to have it done in a week,but this guy could do it for $48 while i waited! i am think on getting it done tomorrow so let me know what you think!

[MERCMAN]

if your planning on keeping the motor for a while do it , seems like the price is great.

[vector mike]

If this prop is from the 70's and lasted over 30 years like it is , I would think that unless you plan on keeping it for more than 30 more years to go with what came in it. Unless the heavier duty hub is the same price.

[Gerben]

Ehhm, is this by any chance an aluminium prop?
Cause if it is, I'd consider getting a new one. 30 year old aluminium gets very brittle and weak.

Gerben

O. FYI, the proper term for "degree" is pitch.

[bloodangels]

I got it fixed today for 50 bucks with in an hour while i waited. I did fins out that the prop was a 12 x19 and the guy said i could go up on the prop a little to a 13.75 x19 or a 13.75 x 21 which would have bigger blades and lower my rpms down from 42 mph 5200 to maybe 48 mph or faster to 4700 . does this make since whith this 1970 mercury 1350? I am looking for a better prop to give me the best of both worlds speed and hole shot for skiing. let me know what you think!
Phillip Kastrup

[bloodangels]

It a bronze 3 blade 12x19. I did get the heavyer one. i do plan on keep it for a while.

[vector mike]

I don't know about gaining 6 mph while dropping 500rpm. I wouldn't run that motor at 4700 WOT. You will do more damage than good. You don't want to lug the motor. It would be like taking off in 5th gear in your car. NOT GOOD! You need to keep your rpm on the high side of your max rpm range at WOT. I used to have an inline 6 and would run it to 6000 at WOT. Plus a prop with more pitch will kill your holeshot.

[gaineso]

If you're only turning 5200 RPM you are a little overpropped now. You could go down a little and pick up some hole shot and top end. Plus, it'd be easier on your motor. You really need it to turn up about 5600 to 5800. Unless you are trying for ultimate performance, get either an Aluminum or one of the composite props. Of course, if you can afford it, always go with a stainless prop.

You might want to try a 13 3/4 by 17.That should bring you up to 5600 R's and better hole shot and top end.

Use Mercury/Quicksilver Premium Plus oil and be sure to add just a little extra. somewhere between 40:1 and 50:1. Use mid-grade gas. Use Quicklean per bottle directions.