set up/impeller question

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handyandy

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So recently I finally got around to putting the jet pump on my 1993 60hp mariner that I've had on my boat. So here is a description of the set up 1554 excel boat it has a mod v front that goes to a smooth flat bottom center keel ends about 2ft or so before the back, it is 15ft long 54in bottom width. Gas tank is up front boat sits almost completely level without me in the back. I have atlas micro jacker jack plate only 4" set. The boat is heavy for it's size it's a 1/8"/.125" thick hull, Longitudinal stringers, welded in floor, with boxes going up each side. Great hull extremely tough, but heavy for it's size. It has some dings on the bottom but nothing bad. I previously had a 40hp nissan/tohatsu carbed prop outboard on it. Ran pretty well with it, low 30's with just me upper 20's with duck hunting load (2-3 guys, guns, decoys, and gear so decent load). I figured the hull could work pretty well with a jet being it sits nice and level, it's tough, planes easily, smooth flat bottom, slight mod v front to help disperse air/bubbles, jack plate doesn't set the motor to far back but would allow me to go between prop and jet. Reason I wanted a jet lot of my fishing is done in shallow, snag ridden, sandy/gravel bottom river with some shallow riffles that I can't quiet get through all the time with the prop. But sometimes prop is better for marshy areas I go to hunting where weeds I imagine would cause more headaches with the jet, so that's why I want to be able to switch. I know most don't suggest it you need to pick on or the other.

So I knew the 40 was just enough with a prop so putting a jet on it was out as I figured the power loss would just be too much and would perform poorly. So I figured a 60-70hp engine with a jet would be adequate as they should be around 40hp at the pump. So I hunted around and got a ok deal on a older 1993 60hp tiller steer mariner that runs pretty darn good that had a prop lower on it with a quicksilver stainless prop. So I mounted that on the boat with the prop, and dang the boat scoots with it. Then hunted down a outboard jet for it took a while, but got a deal on used one that was in almost new condition. Clearance between the impeller and liner is nice and tight, very few scratches in the liner, the impeller is in great shape all the shims are on the bottom, bearings are in great shape, only thing I did was change the drive shaft from a long one to a short one.

This past weekend I finally got around to putting the jet on it on the engine. Raised the jack plate up all the way and even set the motor on the highest bolt holes to give me the most room for adjust down or up finitely with the jack plate. Well I got it on got the shift cable and shifter dialed in. Made up a different transom saver for the jet foot. Stick it in the water and man was it disappointing. I knew the jet would be weaker than the prop, but crap I figured a sixty would have the balls to at least plane the boat out. I had a little load in it but not a lot. Just me and duck/goose decoys in the boat probably about equivalent of another guy in the boat. I'm small only weigh 150, decoys maybe another 150, 6-8 gals of gas up front, battery in back, trolling motor up front, so not really a ton of stuff. I know jets are sensitive to their set up, but I tried different trim levels, all the way down up a little. I tried the motor raised up all the way which made it cavitate some, down to much to where it was spraying, where it seemed the best not cavitating not spraying a lot. But I just couldn't get it to plane out. Just didn't seem to have the power which I figured it should have had enough to at least plane out and get into the mid 20's.

The things I really wonder is one my AG outboard jet currently has the 6 5/8" impellar and liner if I'm measuring it correctly which was meant for 50hp varieties of my engine 60hp was suppose to have 6 7/8" impeller and liner. How are you suppose to mesure the impeller and liner want to make sure I'm doing it right? If this is the case and I have a slightly undersized impellar would that slight 1/4" jump in impeller size make that big a difference? The other thing I wonder is I wasn't running any kind of spray/water tab on the bottom of the transom do they usually help that much? I think a tab could make some difference, but I have hard time believing it would be a big enough difference to get the gains I need. The engine certainly didn't struggle at all with the jet open it WOT it revved right up to whatever rpm it was running sounded higher than it ever did with a prop. Can't say as to the exact rpm though no tac gonna order one.

Sorry for the long post just tried to make it detailed and give necessary info. I have read a lot on here and elsewhere on the set up of jets, but I'm still all ears as many of you have much more experience than me. I'm hoping the larger impeller might do it. If so is worth spending the extra on a stainless one or just get aluminum to try it out.
 
picture to help see how it sits in the water with the 60 and decoys in and some other gear
 

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60/40 should run that boat. I would have to hear the sound of it running to have a better idea what might be going on. Post some pictures of the height you have it set at.

A simple to thing to check is make sure you gate is swinging out of the way of the nozzle.
 
will do that pic is with the prop on in the area I'd probably continue to run the prop due to open water choppy sections of the lake, and weeds in the back waters I hunt. Didn't take any pics this weekend with the jet on and it raised up will take some this evening and get them up. I figured it would push it and imagine it's in my setup. Not sure if I will have time to stick it in water this evening will try to and take video so you can hear the engine.
 
If your motor has a 6 5/8 impeller that's your problem. Your right it should have a 6 7/8 impeller. Remove your shoe and measure the inside of the liner at the top to see what size liner it has. Some times the impellers have the size stamped on the end right under where the nut goes but some times they don't. There's a used 3 blade stainless 6 7/8 on ebay right now for $165 or so but it look s a little eat up on the leading edge or hears a link to a new stainless https://www.ebay.com/itm/360984595841?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT best price I've found on them. Aluminum impellers are cheaper but you'll buy 5 aluminum before you wear out a stainless.
 
hey thanks for the link to ebay I'll measure again to make sure this evening that it is a 6 5/8". Hopefully I have enough time and daylight after work this evening to put it in and take video. I called outboard jets a little while back the serial number on it brings back that it was a 50hp AG which the only difference was the impeller and liner size between it and the 60hp model. Even after buying the drive shaft, shifter cable, and even maybe a impellar and liner it stills puts me pretty far a head of the cost of a new pump. Rude I'm pretty jealous of your omc I've always been a omc guy prior to having the nissan which came on my boat originally and now this mariner. All I had was omc 1965 9.9hp johnson to start, then 1975 25hp johnson, then 1989 40hp johnson that I should have never got rid of.
 
so took some pictures and videos forgive the poor quality of the videos was solo so was hard to take a video run the engine and try to adjust trim and jack plate height here and there.
 

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more pics of impeller liner, and intake. It all looks to be in good shape although it is indeed a 6 5/8" impeller liner. If I have read and heard correctly I have a flanged liner? Anyone know what the best source for the liner is? I know I could call outboard jets, and jet doctor has them wasn't sure if there was any place cheaper or better.
 

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I'm a complete idiot for not realizing it in person when I put on the darn jet lower and working on the darn thing so much. Wasn't till I looked at my own pictures I took now uploading them but I've had the darn intake backwards this whole time when I've been running it ](*,)

I can't believe my own mistake right now. Well guess I will put it back together right after work today with the intake going the right way and see how it does. On a positive note since I took the intake off last night I went a head and sharpened up the impeller. Will probably deburr the grate bars right after work get it together properly this time and test again.

I wanna kick myself in the *** for not realizing I put the intake on backwards.
 
An idiotic mistake is one that tears something up. This is just an oversight. :lol: At least an oversight if you didn't over rev the engine if it was cavatating because of the backwards foot.

Hopefully that will get you in business. Pump looks like it's in good shape...liner, impeller, and all. Sharpening the leading edges on the impeller will help a little.
 
it was reving a little high but nothing major at the highest setting with the jack plate it cavitated a little so surged up hear and there but nothing major and not very any length of time. We'll see how it does after work hopefully it will run pretty well. I'm not looking for setting speed records just want to be able to plane out 2-3 guys with duck hunting crap is the heaviest load it will see. Which can be a decent load depending on the amount of decoys and what not. Summertime it's much lighter with two guys and fishing crap for cats/smallmouth
 
Well at least you got part of the problem solved. lol That's definitely not a flanged liner. Flanged liners are set down in the shoe and have a flange around the out side that the 6 bolts that hold the shoe un run through. Your liner is held in by 2 bolt one on each side of the shoe so it's not a flanged liner. You'll still need the 6 7/8 impeller because a jet always has a constant load unlike a prop so it doesn't matter what load you have in the boat a jet is going to turn a constant rpm.
 
Last I talked to them it was a AG that came with a 6 5/8 impeller/liner and it does indeed have one from what I measured. Which was intended for 50hp models which were identical to my 60hp carbs were just smaller and exhaust tuner was different, displacement, the midsection, and lower were the same. Since it already has the 6 5/8 stuff in it I'm gonna turn my intake and see how it does. Will order the 6 7/8 impeller/liner but figure it's worth a try with what I have.
 
well flipped the intake around to it's facing the right way now, still can't believe I did that. Took it out for a rip yesterday evening and it runs pretty darn well now. Was able to get 29-30mph out of it. Thats with the 6 5/8" aluminum impeller so I'm hoping with a 6 7/8" stainless one that it will bump it a few mph. Either rate I'm happy with it. The power jack plate is nice to be able to adjust to optimal height on the go cut into a turn I can lower it a little to keep it pumping water through on hard turns and get up higher on straights.

This was with me and a bunch of decoys in the boat didn't feel like unloading it since I will be hunting with all this coming weekend.
 

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