What RPM should I run at

"I was told by previous owner

"I was told by previous owner not to run motor past 4500 rpm, the owners manual says after breakin period you can have it at full throttle which is well beond 4500 rpm the boat is 71 v-6 400 series 155hp any suggestions? thanks dave"

"I take it you haven't had

"I take it you haven't had it out on some nice flat water at full throttle yet? You should you need to know where your "WOT" RPMs are.(Wide Open Throttle) To know that you have the proper propeller for the boat and engine. Best is to do it on a calm day with about 1/2 tank of fuel, maybe you and a friend and adjust the drive trim till you get your best speed then quickly look at the RPM gauge and note what it is.. Then you need to look in a manual and find out what the WOT RPM is for your engine and see how they compare."

"I had it out last weekend and

"I had it out last weekend and it did good for first time out and I took it to about 5500 and it ran great but with how old, amount of hours on motor I dont want to blow it up. The motor still has more and my tac goes to 6500. I had it WOT untill it gets to around 4500 then id back off, due to previous owner stating you shouldn't run past 4500. The other thing I noticed is that when running it steady the temp would raise to 3/4 hot it never reached hot but to close for my comfort. the impeller was changed last year and the water flow from the unit seems to be good, is this typicall of these motors?? im really new to boating so any help is greatly appriciated. thanks again Dave"

"don't take it over 4500.

"don't take it over 4500. If you are able to go over 4500, you should change propellers to one with a higher pitch number.
If propped right, it should be impossible to get over 4500"

"And there may be a reason the

"And there may be a reason the temp went a little high, could be a restiction in the manifold or the engine circ pump could be worn.

What prop do you have on it ?"

"MAN!!!!! You pushed that old

"MAN!!!!! You pushed that old motor haarrrrrd. I have the SAME setup, and WONT go above 4100. Check the validity of your Tach, as well with a newer device. Have the throttle cable adjusted. Mine wont go above 4200 at WOT. IMO...your getting too much throttle. I re-pitched my prop to a 18 from a 16, and it seems great for the 20 footer."