RPM range @WOT

My 40 1993 40 hp Evinrude is running at almost 7000 rpm at WOT according to the tach. It does not sound as if its winding out but I dont want to damage this otherwise good running motor. My prop is a 13 pitch. I'm not sure if the tach is correct or not. I do not as yet have a manual but one is currently ordered. Any one have any suggestions?<br />Thanks,<br />Tim

Re: RPM range @WOT

tabot - I wouldn't run that motor at WOT until you get the manual. Most OMCs are max rated at 5-5500 rpm at WOT but cann be run up tp 6K with no problems - - but 7K????

Re: RPM range @WOT

I agree. My brother told me he thought that was pretty darn high rpms. I'll keep it down at the 5500 range till I see further. <br />Thanks alot!<br />Tim

Re: RPM range @WOT

The tach may not have the proper setting for that motor. I say that because the 1993 OMC manual indicates that the powerpacks have a built in rpm limiter of either 5700/5800 rpm or 6200rpm depending on model. <br /><br />When I was setting up my 1993 40hp, I too had a 13 pitch prop that would let the motor over-rev at wot and hit the rpm limiter. It feels like the motor is loosing power or like the prop is not actually in the water. <br /><br />You didn't indicate what size/type boat its pushing, but with my boat/motor I ended up with a 15 pitch cupped Hustler aluminum prop turning 5000 rpm WOT. <br /><br />Depending on which model 40hp you have, the tach pole setting will be different. If you have the 12 amp regulated system (look for the rectangular finned aluminum regulator near the powerpack with the fins running vertical) set the tach to the 6 setting. If you have the 4amp non-regulated system, (no regulator) set the tach to 5. <br /><br />Edit: One important bit of info: Almost all tach manufacturers list the pole setting incorrectly as 5 for all 2 cylinder Johnson/Evinrude 40-50 hp models starting with '93. I spent a lot of time verifying the setting is actually 6 for 12 amp models. All 93 40 - 50 hp have a normal wot suggested rpm range of 4500 - 5500.<br /><br />Good luck.

Re: RPM range @WOT

Thanks for the suggestions Mark42. After talking to the previous owner today, I found out the prop had been changed to the 13. I am not sure of the original pitch. Given the current wot rpm of 7K I guess that I need to either reprop or watch my rpms. What speed do you achieve with you current setup? By the way, I have an aluminum hull 16' deep V and Evinrude 40 hp TE40ELETB. At 6K rpm I am currently showing 19 mph. At wot 7K, 25 mph.

Re: RPM range @WOT

tabbot ,Mark42 alluded to the setting on the back of the tach.Did you check to see what setting it was on? Also a brand name or numbers off the back of the tach.Someone can let you know where it should be set.

Re: RPM range @WOT

Thanks OB I'll go check now.<br />Tim

Re: RPM range @WOT

If it's an OMC tach ,if it's like mine,the setting adjustment doesn't have a detent for positioning in the exact range.Had some issues with tach fluctuation last summer til I found out the selector was not set exactly to position 6.

Re: RPM range @WOT

The tach pole settings are as follows: 4, 8, 10, 12. It is currently set at 10. I see no indication as to the manufacturer of this tach. The boat is a 1993 Tracker Pro Deep V 16. All gauges appear to be stock.

Re: RPM range @WOT

ob: I'm starting to feel that my tach setting may be off given what I see(position 10)on the tach and what mark42 is saying the setting should be. The problem is that my tach does not indicate a 6. Would that be some gray area after 4 but before eight. I guess that I will need a dwell tach to calibrate??? Not sure. All help appreciated.

Re: RPM range @WOT

The 10 setting is incorrect. This is equivalent to the 5 setting previous posters pointed out. Setting it to 12 will be the equivalent to 6 on current tachs. Your tach will then read 6000 at WOT and that's where your engine likes to be. My '95 Evinrude 40 has spent a good amount of its life at those RPMs and runs like a top.

Re: RPM range @WOT

Different tach manufacturers numbering is different.Without the literature I couldn't tell you for sure on yours.Maybe someone else can though.I'll be listening.<br /><br /><br />Edit : There you go.Test it out and tell us what you find.

Re: RPM range @WOT

Thanks upinsmoke and OB gonna change it right now. I truly appreciate all of the advice.<br />Tim

Re: RPM range @WOT

Hope it puts you in the sweet spot on rpms.Other wise you can start playing with engine height and prop.

Re: RPM range @WOT

I hope it doesn't get beyond the tach. It seems to act fine at wot now aside from reading 7K. It always sounded fine but dont trust the ears as much as I do the eyes. Thanks and I post soon with the final results.<br />Tim

Re: RPM range @WOT

Hey fellas,<br /> Took the boat out today, After making the change to the tach setting I am now showing a WOT of 5500 rpm. I'll take it!<br />Thanks to you all for the advice. You were dead on upinsmoke. Now I feel that my motor would like 6K like yours upinsmoke. Any suggestions other than reprop?