1996 ski nautique rpm adjustment

change the prop

thatdude596 wrote: change the prop

Talk about jumping the gun! A little more info is needed first.

My '90 ran 41mph @4200 RPM when I bought it. While an underperformer for sure, there was nothing majorly wrong with it- thats just how a slow hull with a stock 240hp engine and original-ish prop runs.

You'll need to fill us in on what prop is on the boat now, as you'd likely benefit from a new one. Though, I wouldnt expect to exceed 43-44mph once tuned up properly, even with a new prop. To push a slow hull faster, you need more hp. Im curious why you put a 750cfm carb on though- that is not the correct size for a 351w and is likely to cause you to underperform somewhat compared to the stock 600cfm.

Fl Inboards wrote: Hardly a slow hull. Our 92 with the Apex ran 51.6 mph on Star Gazer GPS yesterday at 5230 rpm and a 422 ACME (because I did not have a OJ to put on it)Thats six liter teritory! 4200RPM and 41mph seems a little on the shy side maybe 2-3 mph slow I would think even a 240 hp motor would approach 4600 rpm.

I havent been in a "No Wake Zone" hull that was good for 4600 RPM with a stock sized prop when matched to the 240hp motor... 4300-4400 has been more typical, and Ive seen worse. My uncle's '90 was touching 43mph with the stock 14x16 Federal, but my other uncle's '92 is only good for 42.5 with an Acme 612. I think that '90 might have a little more in it once its dialed in with a better prop, as it seems to ride slightly more bow-high than both the '92 and my '90. Ive heard of some stock hulls being good for 44mph with the base motor, but I havent been in one personally. Id say my 351w is built up a bit stronger than that Apex and I still dont see a great top end (47ish).

Im not sure if some hulls popped out of the mold differently or if there were multiple molds (one being faster than the other), but some hulls just plant the nose and are simply slow. Of course, some werent- my uncle had a '95 with a GT40 that run 50mph according to the Airguides... and I dont doubt it was good for all of 48-49, if not more.

Long story short, definitely need more info... but if everything checks out, 42mph @ 4200 RPM may not be far off from what the boat is capable of.

Welcome Mark. Where you at in Illinois? Quite a few members here

Mark,since your so close keep an eye out for the Clinton Lake get togethers ,you'll have a good time with a great bunch of people.

levinmark wrote: When i bought it the carb needed replaced. It was replaced with a pcm holley 4v model. I'm not sure what cfm it is. I thought 750 but i might be wrong. The engine is a pcm 351 ford with the red valve covers (gt-40 heads?). The engine model number is #pldprr12pp. The prop is the original prop (3-blade). Not sure what size it is.

Well we're getting closer... depending on who sold you the carb, its likely you got the correct one. Im not aware of a PCM that came with a 750cfm carb, as even the big blocks only came with a 650cfm. Its quite likely you got the correct 600cfm Holley 4160. Pull the LIST number off the front of the choke horn and we can verify that for you.

Both the standard (240-255hp) and HO (285-300hp) versions of the 351w came with the red valve covers, so that isnt a clue... but the ID tag doesnt lie. PLD means youve got a LH base 351w (no GT40 heads) with the 1.23 transmission. Its possible you need a tuneup, but I dont think your numbers are too far off of what you can expect from that hull/engine combo. Do pull the numbers off the prop (they may be obscured by the nut) so we can verify if its the original wheel or not.

If you do a lot of barefooting, you would probably have a good appreciation for a bit more hp. A proper head/cam/intake upgrade would put you just north of the 300hp mark. Combined with a modern prop, the boat would drive completely differently (better holeshot and throttle response) and would likely be good for somewhere around 47mph or so. Its a proven upgrade and would set you back somewhere in the $1500 range if you do the work yourself (not too difficult), add another $300 in the budget for a new prop. We can walk you through that if you have the interest.

...again get a new prop..many will let you try them before you make a final decision on one. i cant see spending 1500+ to gain 4-5 mph. thats a new prop and a lot of boat gas for the new season

thatdude596 wrote: ...again get a new prop..many will let you try them before you make a final decision on one. i cant see spending 1500+ to gain 4-5 mph. thats a new prop and a lot of boat gas for the new season

Again, we dont know what prop he currently has- so recommending he get a new one is still somewhat premature. The trial and error has been done on his hull/powertrain combo, so if he can give us a bit more info on his current performance and how he uses the boat, someone can give him good recommendation on what to buy. All the places that offer free demos charge full retail, so we can potentially save him a few bucks.

As far as $1500 being worth it, thats up to him. Many will tell you its some of the best money theyve spent on their boat. Yes, a new CNC prop is highly recommended before doing any other upgrades, but its not going to help top end speed a whole lot. The 240hp motor on a slow No Wake Zone hull is a borderline capable barefoot boat... I know mine wasnt capable of pulling me fast enough (41mph) to comfortably do 1-foot tricks, even with an Acme pushing it along. Now it does an admirable job at giving me 45 if I want it- and it can pull 2 big guys that fast if need be. Having a boat capable of that may not be important to you, but it is to me. It doesnt hurt to inform this guy of all his available options.

what I really ment is that you won´t find a prop will make you gain 4-5 miles...

thatdude596 wrote: trb-he stated he has the original oj 3 blade above. your the prop guru,does he need more holeshot or top end mainly? 540 for top end? 1422 for holeshot?

He stated that the prop is original, but does not know the type or size. Without knowing those details Im not sure how one would draw the conclusion that its original, so at the very least Id like to positively identify it.

The 540 is a 1:1 prop and wouldnt work here; the 1422 is not a real model number as far as Im aware. There are a number of options that I would consider that would improve his overall performance- but none that would improve his top end significantly, which is his goal. Id still need more info before getting into specifics.

geez fellas, that sure is a lot of information to process. I will start by heading out to the garage to check the numbers on the prop to identify which one i have. I definetly dont want to spend another 1500 at this time. I love to barefoot for the hell of it and mess around with a tumbleturn here and there, but am definetly a slalom skier at heart, therefore, a few more mph for that money isnt at the top of my list. The holeshot and consistency of that is important and really dont want to comprimise that. I just thought i would ask to see if I could pick up a little more top end some how without spending a bundle. You guys are full of info and I really appreciate all the input. I will get back to you on what prop is on it. If there are any other details you need to know, let me know. This Correctcraftfan website is great, and look forward to many more chats with you all in the future

thanks again

Hey Gary, Its Mark from Pontiac.

I'm curious where else you guys go to boat. I'm trying to get in at South Wilmington, a private campground with a strip mine that is about 1.5 miles long, by a .5 mile, and another .5 mile, unbelievable, if there is a little chop, just go around the corner and you have glass. We have a few friends we go up there with, only problem is getting a membership. I'm working on that this winter. Anyway, I have been looking online for ski clubs around the area or other lakes that might be a diamond in rough. I love to slalom and barefoot, so obviously im looking for a place with calm water that might not be used by many people except for others such as ourselves. I'd appreciate any feed back from you and your friends on places you would recommend.

Thanks,

Mark