Prop Help

[bamafaninfl]

1977 170 I have a new 90 yamaha 17 pitch SS prop 4800rpm WOT If I go to a 15 pitch will I still have a good hole shot and will I get more RPM`s  Thanks for any info (pic`s in the photo gallery still show old motor).

[ddd222]

i forget whether you should go bigger or smaller, you should be spinning 5300-5700 rpm wot, or thats what my mechanic says, and should not lose any significant holeshot, unless you are a professional waterskier or something

[John Jones]

Normal rpm change at WOT is around 200 rpm/inch of pitch.  Dropping to a 15" should bring you up about 400 rpm and should put you close to the proper WOT.  Hole shot will not suffer with the proper prop.  The shorter pitch prop is easier for the motor to spin up therefore the motor will get up to the peak of it's torque curve faster thus actually improving hole shot.    Running at the high end of the recommended range at WOT is recommended by most experts for economy, performance, and engine life.  When you get it to this point you will notice a significant difference in response and fuel usage.  What you have now is like driving a car at 30mph in high gear, lugging, which is not good for the engine, performance, or fuel economy.

Personally I would shoot for 5800 @ WOT.  

The last I heard, Overtons will work with customers on finding the correct prop and will swap props with no problem if you haven't dinged them.  Some dealers will, some will not.  I would not buy from someone who will not swap out if it isn't right.

http://www.overtons.com/props/materials.shtml

$0.02

[GoneFission]

Going from a 17 to a 15 pitch will actually improve your hole shot and will allow the engine to run at a higher RPM wide open.  I would be surprised if you needed to go lower than a 15...

Also, it may sound silly, but make sure the tach is reading correctly and set to the proper setting for your motor (# of cylinders and/or pulses).  I have seen cases where the tach was set incorrectly - an obviously the RPM was different from that indicated!    

Good luck and good fishin'!