Propeller replacement help .

[Sea swirl captain]

i replaced my prop at the end of the year right before I removed it from the marina . I have a 1991 Johnson GT150 on a Omc sea swirl boat and had a Michigan Wheel Ballistic 14 -1/2 x 19 RH 345033 prop which had three blades ,the prop was spun on its hub . I could not find a pressed in hub for the old prop so I got a new one . I replaced the prop on the advice of the marine store with a Turning Point Hustler 14x19 RH four blade prop. Before I replaced prop I could cruise along at wot 5600 rpm and 58 to 60 mph. Now with the new prop wot is 4200 rpm and max speed of 43 mph ? Only other thing I did during the winter was raise the engine up two holes so about 2.5" s on the advice of the marine store . So is this prop no good for this boat or is the problem raising the motor?

 

[WesNewell]

IIRC each hole is .75", so that would be 1.5". And that;s not the problem. Suspect you need a tune up. Somethings not right with the engine, You shouldn't have lost that much rpm just going to a 4 blade prop of the same pitch.

 

[jimmbo]

Sounds like you lost a cylinder. Start with the basics, Compression Test. Spark able to jump a 3/8" gap. Did you put fuel Stabilizer in the tank and run it so it got to the carbs when you put it into Storage?, if not, Dirt/Varnish in the carbs, plugged main jet/nozzle.

 

[Sea swirl captain]

Yes I did use fuel stabilizer and put it in before I drove it to the bost launch , seems to run fine . I will check compression and spark , I did replace float needles and jets because the floats were not shutting off gas and fuel was leaking out of the jets . I did check for spark with a old in series timing light and spark was present in all wires before I put it in the water . Also regaled plugs .

 

[porscheguy]

Most prop shops should be able to install a new hub in your old ballistic prop. They’ll probably clean and polish it up like new.

Let’s look at your data before everyone has you doing an engine rebuild. From my research, your motor has 1.86 gear ratio. You said you were running at 58mph @5600rpm on the old prop. I’m afraid this isn’t possible. That would result in -7% prop slip. You can’t have negative slip. with your new prop you’re still at -1% slip. Still not possible.

I do believe its possible that you’ve suffered a drop in performance with this different prop, but you need to have accurate data to determine where it’s falling off.

 

[WesNewell]

Assuming his boat weighs 1560#, 48-50 mph is a more reasonable max speed for the GT150 with 2 people. But going to a 4 blade shouldn't have owered his rpm that much, so something either wrong with the data, or the engine.

 

[QBhoy]

I’d say this may be down to the prop. Having had a ballistic on my boat, they can be incredibly quick on some boats. Allowing some seriously high trim and hull lift.
Youve went from a well suited performance prop to a pretty cheap 4 blade. 4 blade compared to a 3 blade (especially a semi cleaver like the ballistic) will always be slower in the same pitch. Usually have a bigger diameter too.
That said. It’s a hell of a drop you’re seeing. The engie height may also have a bearing.

But you will certainly not see anything like the performance you had with the ballistic going to the 4 blade you did. Even comparing the excellent laser 2 prop I also have to the ballistic of the same pitch. There was a drop of 3/4 mph compared to the ballistic when it did perform. Trouble is it wasn’t consistent in performance all the time. Eventually sold it and now go between the enertia and laser and 2” of pitch either way. Hope it helps.

 

[Sea Rider]

If both props are 14 x 19, the original one being 3 blades and the new one 4 blades, should expect that high wot rpm loss along speed. When going from a 3 blade to a 4 blade aren't you supposed to go per 1-2 less pitch size, say a 18-17 pitch ?

Happy Boating

 

[Sea swirl captain]

I think it's the prop but have not been back to the marina since I backed in and ran my Honda kicker into the dock and broke the rubber motor mounts . I went over the bills for the boat that I got with it and it has been modified a bit bigger pistons and not stock Johnson parts ? Also the gearing has been changed in lower end but I did get the original lower end with boat . I had access to a scope to test boat when I got it but am retired now and don't have access anymore. It was running over rated rpm quite a bit so we slowed it down to 5600 to 5700 rpm was screaming up to almost. Up to 6000 rpm and to scary for me on the ocean almost no boat in the water maybe the back two feet in the water . I will put my spark tester on each cylinder and see what's up ,maybe poor spark or maybe missing a cylinder . I put some marine epoxy I the end of the ballistic prop hubto get it to stop slipping to see if I can test to see if it will get up to speed again I don't pay much attention to the speedometer because I t seems to be off a bit , I use the two gps low rance units to tell me speed . The dealer that sold me the prop doesn't seem to want to phone me back ,surprise surprise. I am going to check everything out tomorrow or the next day and then phone dealer from a different phone number if it turns out to be the prop sizing , he originally said to test this prop out and if i didn't like it I could return it .

 

[Texasmark]

Yes I did use fuel stabilizer and put it in before I drove it to the bost launch , seems to run fine . I will check compression and spark , I did replace float needles and jets because the floats were not shutting off gas and fuel was leaking out of the jets . I did check for spark with a old in series timing light and spark was present in all wires before I put it in the water . Also regaled plugs .

"Replaced the jets" Bingo. Jets were smaller ID than OEM betcha! Agree too much change for your prop swap even though you went to a TP Hustler which is alum and 4 blades.....give it -100 rpm for the alum vs SS material and -200 for the extra blade. You are no where near those numbers.

 

[Sea swirl captain]

I have been back to marina at night and tested spark ,spark does jump the 7/16 gap . The float valve& seat are part number 0396520 which I got from Evinrude dealer . I hope they are right . I will go back to boat tomorrow and check compression with my annoying wife to turn the boat over while I test . If everything checks out I will go for a ride on Monday with the old ballistic prop and see what happens.

 

[jimmbo]

You can rig up a switch to the Solenoid and you won't need the Annoying Wife to turn the motor over. Wives are best left ashore. A male needs as much time away from a wife as possible.

 

[Sea swirl captain]

I know exactly what your saying Jimbo ,it is best to get away on your own as much and as often as you can . I have a theory that if I bring her down to the boat and fire up the 2 cycle GT 150 to warm it up before I test the compression the memory of that trw oil smoke should keep her away from the marina for a long time The river and marinas are a pain to try and get your boat into your slip with the dam river current. I often wish I was back on the lakes around Edmonton where I would just drive the boat up on the beach, or drive up to the pier and not worry about running into the boat beside me . Just came back from the marina and the tide was out ,the boat motor was on the bottom when I put the motor down so will go back tonight . I don't want to suck any mud into the motor.

 

[jimmbo]

I learned why Married Men die younger than Single Men...

Cause they want to

 

[Sea swirl captain]

Well I tested compression on motor all 6 cylinders are between 90 and 95 I think that's ok for a 1991 GT 150, think I will change the plugs and go for a ride with the old Ballistic prop to see if the new prop is the problem. I learned years ago it is best to ignore everything that comes out of the wife's mouth.

 

[Sea swirl captain]

I ran a can of sea foam mixed with a gallon of gas through the motor and managed to her 5000 rpm and forty eight miles per hour with the prop slipping so new prop and probably motor height is the problem , I will see if I can give it back and get one size smaller . Carbs probably need jets cleaned too.

 

[QBhoy]

Hi
it is still going to be down to the two different props. The ballistic prop is still well known for literally ballistic performance and capable of taking much more trim than even some of the best 3 blades.
Going to a 4 blade of the same pitch compared to even the worst of the 3 blade stainless will always have a drop in performance, rpm and ability to take trim.
I excuse the above only to say that some boats perform differently of course but with the exception of a rev 4 and having massive power to turn a rev 4....the 3 blade to 4 blade issue I’ve described above is a certainty.

 

[Sea swirl captain]

Thanks for sending that i found someone to insert a new rubber hub , it was in backwards the first time i got it back but i took it back and they put in properly , then i put it back on the motor and the boat is back to normal 5600 rpm , it is a much better prop than the turning point hustler , sorry so long to get back to you but a moved and was doing so much around the new place i just forgot about iboats forum for a while.