1979 Evinrude 140 lower unit gear ratio?

[Theoutdoorsman]

Can anyone recall, off the top of their head, what the lower units gear ratio is on my 1979 Evinrude 140. I'll need this for future reference when determining my prop slip to complete my setup. Thanks a bunch !!!!.................. ALAN

 

[Dhadley]

Re: 1979 Evinrude 140 lower unit gear ratio?

2:1 or .5, divide the engine rpm by 2. 6000 engine rpm is 3000 prop rpm.

 

[Theoutdoorsman]

Re: 1979 Evinrude 140 lower unit gear ratio?

Thanks Dhadley. When determining prop slip, via this calculator......... http://www.rbbi.com/folders/prop/propcalc.htm ........, what would you consider to be an acceptable number in the prop slip field? I am not currently in the phase of my break-in which allows me to open her up, but when I am, I plan to gps the rig and document some numbers as a starting point reference. I plan to consult with you later regarding proper setup. I just wanted to know what number I should be shooting for ahead of time. Thanks again..................... ALAN

 

[Tacklewasher]

Re: 1979 Evinrude 140 lower unit gear ratio?

I'm told 10-12% is good.

Mine is about 10% at mid throttle (3200 rpm) but drops off to about 25% at WOT. But I have bigger issues with my boat.

 

[Theoutdoorsman]

Re: 1979 Evinrude 140 lower unit gear ratio?

Tacklewasher............... Thanks. I'll be digging into this a little deeper after breakin and get back with you guys. Thanks again................. ALAN