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OMC 43L max rpm

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blawton_25

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"I just bought a 91 four winns

"I just bought a 91 four winns 19' with a omc 4.3L. the manual says that the max rpm's is 4200-4600. I had it out for the first time last night and was cruising along on a flat lake, I had it at about 4200 and it still had lots of throttle left. Is there a magic number no matter what prop is on that I shouldn't go above?"
 
"4600 is max. How much is &#34

"4600 is max. How much is "lots of throttle"? Another 1/4 throttle position doesn't necessarily mean a lot more RPMs. I would ease it on up towards full throttle and see what you get. Keep in mind it's best to prop the boat for a typical load of people and gear, and for what you will doing, skiing, cruising, etc. Lower pitch will give you better hole shot for towing but will turn more RPMs at wide open throttle. Higher pitch will get you more top end speed but will turn less RPMs at wide open and may be more sluggish out of the hole."
 
I checked the prop this weeken

I checked the prop this weekend and its a 19 pitch. The manual calls for a 21 pitch and says wot rpms should be 4200-4600. This past weekend at wot with the 19 pitch the rpms were running right at 4500. Is it safe to run in this condition or should I not run at wot?
 
"Well, it depends on how you d

"Well, it depends on how you define "run" I suppose. I don't think any boat should be "run" at WOT for extended periods. It really sucks the gas for one, and it would be akin to running any motor at "redline". Run it at WOT to check for your RPM's (which you did...and their good), and run at WOT to get your jollies. But for "cruising" around the lake, find a comfortable cruising speed/RPM (mine is about 3400 - 3600 RPM and about 35 mph), and enjoy the ride!"
 
"The other thing to consider a

"The other thing to consider as Chuck said, depends what you'll be using it for. If you use it for skiing then you want a decent hole shot. Keep in mind as a rule of thumb every inch of pitch you change will change your WOT rpm's by approx 200. So if you go up to a 21" then you may max out at 4100-4200 and you will lose some of your hole shot."
 
"ok, thanks for all the info.

"ok, thanks for all the info. I guess what I really want to know is what should I set as my rpm limit as I'm cruising around. I realize for short periods it can be a little higher but what is the "recommended" rpm for normal use."
 
"[b]"what is the "reco

""what is the "recommended" rpm for normal use."
There's not one. Naturally, the lower the RPM, the happier your engine will be. Should be able to stay on plane with a comfortable trim angle in the 3200-3600 RPM range. Of course it all depends on the boat and the load it's carrying."
 
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