original prop size

[takefive]

Does anybody know what the factory prop size was for a 1979 46 conv. with 871TI's and 1.5 allison gears?

 

[hattitude]

My 1980 46C w/ 8V71ti Detroits & Allison 1.5 gears was delivered with 4-blade, 26" diameter by 25" pitch props.

I am currently running 4-blade 26x22 props......

 

[takefive]

Thanks Hattitude,
What made you drop down 4 degrees pitch?

 

[dsharp]

It's three inches of pitch. Added weight is the biggest culprit for having to take pitch out. The engine has to be able to reach its rated rpm when it's running wide open. If it won't you either have to take out pitch weight until it will, lose weight or find more power.

 

[hattitude]

It's three inches of pitch. Added weight is the biggest culprit for having to take pitch out. The engine has to be able to reach its rated rpm when it's running wide open. If it won't you either have to take out pitch weight until it will, lose weight or find more power.

That's exactly right, and why I'm down 3" of pitch. I suspect most manufacturers will pitch for max speed, not max RPM. I would suspect for long term engine health, most boats can probably be pitched down an inch or two, right from the factory and before adding all the goodies we just have to have on board.

My boat has certainly taken on weight over 30 years, the Detroits are probably getting a little tired, and I'm a believer in reaching max rpm+.......