SoCal Jet Boats
Tech Talk => Jet Pumps => Topic started by: Nuthead on April 26, 2016, 10:38:46 AM
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On my 18ft Kona seems to porpoise a lot, just bought it acouple months ago. Have to run with my diverter down must of the time. Im planning on adjusting my ride plate but not sure which way to adjust. Right now it look down acouple degrees.
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Three things lead to what you have going on.
The first is having rocker in the bottom. Seriously doubt that's what you have going on, but a straight edge will tell the story.
Second, too low of an X dimension or thrust line. You can scratch that one off too.
Three, trim tabs, ride plate and nozzle relationship all fukkered up.
I would start by raising the ride plate to about 2.5 to 3° "up" from flat to the keel. This seems counter intuitive, but try it anyway.
One piece of caution, that Diverter nozzle looks like an older design. Does it have a reverse chute under it?
A later nozzle can help dramatically.
Also, while you're dickering around under there, check for what loader (if even applicable) you have in that pump.
The JE, JF design is a little fickle when it comes to loading.
Do the rpms seem to fluctuate up and down when she dances?
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Good looking float btw.
GT
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Thanks! It has this style loader on it now (pic below). Motor is 454 very mild. Not sure think it has reverse chute but will have to look again. I put 3 foot level on it yesterday & plate is definitely down in back. Did not notice RPM fluctuating at all.
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I really don't care too much for that loader. (Absolutely no offense intended), but you need to see where the biting edge of the ramps are in relation to the keel line directly in front of it. They should be cut so they are slightly above the bottom of the boat.
The distance varies by opinion, but I like 1/4" to 3/8" above the keel line.
It should also be through bolted with black oxide Allen bolts with locking nuts on top.
GT
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Ok I will check tonite. I also have this grate that came with boat, but was from when it had 600 hp motor. I didn't think I woud have enough HP now for that one.
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Ok I will check tonite. I also have this grate that came with boat, but was from when it had 600 hp motor. I didn't think I woud have enough HP now for that one.
I like the second loader better. Still, needs to be trimmed to work properly.
GT
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beautiful boat nuthead. i was wondering where it went. i was looking at that boat right before i found mine. pretty purchase
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Correct me if I'm wrong Glenn, but isn't that rife plate a little short? Even for a JE/JF. I feel like they are supposed to be longer. The length could help reduce the porposing
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Correct me if I'm wrong Glenn, but isn't that rife plate a little short? Even for a JE/JF. I feel like they are supposed to be longer. The length could help reduce the porposing
Maybe. Hard to tell, but it looks like a stock sized plate.
If someone adjusted it down, it could do some weird stuff.
I have seen shorter plates and certainly longer.
You could totally be on to something.
I'm still sort of thinking that if it was adjusted up it's either going to allow the boat to ride higher and fly the bow a little more, or be one of the wildest riding bronco, Billy sons a bitches on the planet.
Lol
GT
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Checked last night it does have reverse chute at nozzle. The ride plate was set at 4 degrees down. I set it to 2 degrees up now.
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Checked last night it does have reverse chute at nozzle. The ride plate was set at 4 degrees down. I set it to 2 degrees up now.
So, just so you can come to school prepared.
It might be flighty as hell, so be on the ready.
If it porpoises the same or worse, try nudging the diverter up a little and play with the throttle. The whole idea is to see if you get get the hull to take a set back on the plate, this will get the hull to fly a little and ride on the back plate and probably 5'of the back of the boat. If you can get it to settle out, note where the water breaks from the hull. Is it at the seats, behind the seats, just before the engine and so on.
I am pretty sure this adjustment won't fix it, but we want to see if it's better or worse. In thinking it will be a little better, but will be a challenge to drive (the faster you go, the better the handling. ).
It's my opinion that the nozzle is killing you just a little. But we should still be able to make it work better.
Don't forget to check the loader biting edge elevation.
Be safe.
GT
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Thanks for info & help greatly appreciated! Loader looked to be 3/8 above Keel line. I may change to other loader but don't want to make too many changes at one time. Hopefully I can get out to Lake on Sunday for test run.
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Well went to river this weekend. It was way worse with ride plate set 2 degrees up. So lowered it down acouple times and probably back to where it was originally set. Guess this boat just likes the 4 degrees down.
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Well went to river this weekend. It was way worse with ride plate set 2 degrees up. So lowered it down acouple times and probably back to where it was originally set. Guess this boat just likes the 4 degrees down.
About where were you running the trim? All the way down? How low does the nozzle go (in approximate degrees)?
Is there a chance someone has the ram set up wrong?
GT
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Personally, I think a later style nozzle with the flat surface on the bottom will make a giant improvement.
JMO
GT
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About where were you running the trim? All the way down? How low does the nozzle go (in approximate degrees)?
Is there a chance someone has the ram set up wrong?
GT
I was running trim all the way down. Tried slowly bumping it up. The more I adjusted plate down the better cruising ride got. I will have to check degrees down.
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Here's 2 pics while we were cruising up river about 3200-3400rpm
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Just going to say it out loud, you need more down trim. I think someone had the ram installed incorrectly.
JMO, that thing is trying to fly way too much boat.
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Just going to say it out loud, you need more down trim. I think someone had the ram installed incorrectly.
JMO, that thing is trying to fly way too much boat.
looking at that first picture, the diverter looks all the way down, but it looks like its straight. (could be the picture)
But yes that thing is trying to seriously air out.
Im with glenn, try switching the ram around.
Or do you have a better pic of the ram?
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I will get better pic of the ram tonight. I'm new at this stuff so not sure how its supposed to be. Looking at pic not sure how else to install ram?
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I will get better pic of the ram tonight. I'm new at this stuff so not sure how its supposed to be. Looking at pic not sure how else to install ram?
just flip it over if thats the issue.
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Here's closer pic of cruising 3200-3400 rpm diverter mostly down to not porpoise. I will get pic of pump tonite.
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Here's closer pic of cruising 3200-3400 rpm diverter mostly down to not porpoise. I will get pic of pump tonite.
seems to be a lot of lift for only cruising especially with the diverter down
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Here's closer pic of cruising 3200-3400 rpm diverter mostly down to not porpoise. I will get pic of pump tonite.
Reading this, I'm seeing that you think the Diverter should be up.
Totally not the case.
Do you know how trim works? In the normal sense?
Not trying to be a dick, just asking a question, it sounds douche-like. Not the intent. Lol
You only trim "up" until the boat frees up and gets too light (or porpoises) then down just a tad. Different speeds will have a different trim limit.
Reading the last comment makes me think it was driver error and not necessarily a set up problem.
GT
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Not trying to be a dick, just asking a question, it sounds douche-like.
GT
Funny, that is how I read everything you write. Lol
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Funny, that is how I read everything you write. Lol
I only seem to get that from insecure Ford guys. Chevy and MOPAR folks aren't so easily offended.
:o
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I only seem to get that from insecure Ford guys. Chevy and MOPAR folks aren't so easily offended.
:o
Oh no you didnt!!! Lol
Official call out to GT in your southwind!!!
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I don't take it in a bad way at all. I was told I should have a small maybe 1ft to 2ft rooster at cruise. I put diverter all way down on takeoff then tap up twice as I'm going. At a cruise I will tap diverter up acouple more times and feel boat get that light feeling but seems to start porpoising. The boat is new to me so I am learning came from 25 ft Deck boat with outdrive. I took a couple pics tonite of setup.
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I occassionally have a slight porpoise issue when my rpm's are low and the diverter is up a bit too much but I just give her some power which snaps her out of it.
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Oh no you didnt!!! Lol
Official call out to GT in your southwind!!!
Gonna need the two weeks to put the 496 in it.
GT
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I don't take it in a bad way at all. I was told I should have a small maybe 1ft to 2ft rooster at cruise. I put diverter all way down on takeoff then tap up twice as I'm going. At a cruise I will tap diverter up acouple more times and feel boat get that light feeling but seems to start porpoising. The boat is new to me so I am learning came from 25 ft Deck boat with outdrive. I took a couple pics tonite of setup.
Not going to say it's wrong, but whoever told you the roost thing is clueless.
If your going to use that theory, the fastest boat I ever drove had at least a 7' rooster that was at least 200' long.
The hull simply has no idea how high the roost is.
Drive with your butt. Affectionately called the Ass-O-Nometer. Lol
Never mind what the tail is doing.
GT
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Gonna need the two weeks to put the 496 in it.
GT
496??? Ahhhhhh, that's cute!!!
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Ok thanks for info. :beer: Im going to put rideplate down a hair more. I think your right I was just getting bad info on how rooster should be, since every boat is different.
And heres a pic for Fordlover inside my home shop.
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Hells ya!!! Well done sir! 👍
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Figured you'd like that. Luckily my Dad & I enjoy same hobbies so we just split cost. The model A in back is a rolling chassis now & getting a 1970 Boss 302 engine & toploader trans my dad has had sitting in corner of his garage for 30+ years.
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Figured you'd like that. Luckily my Dad & I enjoy same hobbies so we just split cost. The model A in back is a rolling chassis now & getting a 1970 Boss 302 engine & toploader trans my dad has had sitting in corner of his garage for 30+ years.
That is kick ass. Went to a car show last week and nothing is more annoying than old ass Fords with 350 chevys in them. Insanity!
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That is kick ass. Went to a car show last week and nothing is more annoying than old ass Fords with 350 chevys in them. Insanity!
Those guys were just tired if pushing the damn things.
I saw a 40 Ford business coupe a few years ago with a modern 426 Hemi in it. Had to change my shirt because of all the drool. Honestly, it looked factory it was done so clean.
That's a sweet set up Nuthead.
GT
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Just kidding. nice shoebox my dad has a 30 a roller to that he chopped and put a 32 windshield frame in like 15 years ago and then stop working on it. But he won't give it to me lol. Ford,chevy,olds,Vw run what you like
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