Re: 98 180 WOT RPMs, Speed
 

Well if your GPS is confirming now that it is indeed slower I will jump on the spun hub possibility bandwagon. Do you have a friend who can let your borrow a prop? If not maybe consider buying a cheap aluminum prop as a backup and test with it.

Re: 98 180 WOT RPMs, Speed
 

going to give the prop shop a call and see if maybe they changed the pitch for some reason or swapped it with a different one. I know the guts are mine they were as nasty when i pulled it off.

talked to my tech today and he's thinking old gas and a loss of octane. His suggestion was to run it almost empty and fill with fresh gas.

37 gal - 4/5 hr run time i'm guessing to empty the tank. i would think low octane would cause a lean condition and maybe burn a piston. maybe hes looking to create some work :)

couple of pics of the prop and hub

Re: 98 180 WOT RPMs, Speed
 

If you are turning the same RPM's as before then its not going to be a pitch change or old gas/octane issues. Your RPM's would change if either of those were the cause. How is your hole shot?

Re: 98 180 WOT RPMs, Speed
 

I dont buy the gas idea either, throw in some fuel additive for the old gas. I hope you figure it out though its got me scratching my head.

I would go to the prop shop and they likely will give you a couple loaners to try a couple different pitches and do your investigation that way. You will need to buy a second anyway, thats something you should have as a backup. And with a couple to compare info on you can really come up with some solid info.

Re: 98 180 WOT RPMs, Speed
 

WOT = throttle all the way down, no more room to more it forward, correct?

Reason, I can reach 4800 RPM with more room to go. I've been real careful not to go any higher but hit 5000/5100 a couple of times by mistake. (Hand on throttle, hit wake, jammed forward).

Re: 98 180 WOT RPMs, Speed
 

Yes WOT is all the way and trimmed up. I believe 4800 is the proper RPM's for the 4.3 at WOT. If you are getting more than that you need to change your prop to a different pitch. If you have a 19 now you would probably need a 21. With changing pitch its give and take. By going up you will lose a touch of hole shot but gain top end speed. The reverse is true for going down in pitch. None of this addresses a different speed this year from last year though.

Re: 98 180 WOT RPMs, Speed
 

You might have the wrong prop reinstalled by accident or old fuel. Bad hubs or slipping hubs will show up just when the boat is planing off. That is the biggest strain on the prop. Within a few hours the hub will slip more and more.

Re: 98 180 WOT RPMs, Speed
 

Well an update. Bad weather has slowed getting to check out at few things. Had the prop checked by the guys that rebuilt it and everything checked good. 14-19" is what I have, Hub in working order. so one thing out of the way.

Next check cap, rotor = good
trace wires = good
checked oil = looks good, no water
pull plugs = cylinders 1-5 good

cylinder 6 plug had some water on the plug. cranked engine a few times no water came out of the plug hole. going to hook it up to the hose later and let it run for a little bit an recheck the plug.

any thoughts?

Re: 98 180 WOT RPMs, Speed
 

Ok so I cleaned and dried the plug. Cranked the motor a few times, very little water came out. Hooked up the hose and run it for about 20 min. Let it cool down. Rechecked oil no water, pulled plug no sign of water......so I guess ill try and get her on the lake this weekend and see what happens

Re: 98 180 WOT RPMs, Speed
 

I am kind of in the same situation... Just got my Z222 out this weekend and can only hit 40 with a good tail wind but really only around 38. I do have a SS 21p prop on the 5.7. Any ideas? Not sure of the last time this boat had a tune up as I just bought it earlier this year. It seems to start normally, acceleration is decent but tops out at 38.:confused: