'78 Johnson 85hp Specs needed

[Bob_VT]

I would like to re-prop my '78 85hp Johnson. The exsisting prop is workable however, there is room for improvement. I am unable to locate any information on the WOT rpm. I want to re-prop without doing damage. Does anyone care to share what the WOT suggested rpm is? This is motor is mounted on a 15' Steury (1000lb hull weight). Thanks in advance.

 

[JB]

Re: '78 Johnson 85hp Specs needed

Don't have User Manual specs, Bob, but Clymer manual refers to 5000rpm as "max" at w.o.t. in several places. Under rpm at which to run a test wheel in a tank, it gives 4800.<br /><br />Based on that I believe you will be safe in using 4500 to 5000 rpm as operating range.<br /><br />Maybe someone else has more reliable numbers.<br /><br />Good luck.<br />JB

 

[Dunk]

Re: '78 Johnson 85hp Specs needed

Those V4's are all rated 4500-5500. The test wheel spec are right for an 85, but they use the same test wheel for the 115 and the 140, so it has to fit them all. The lower powered V4's put out there best power at 52-5300.