1993 Johnson 120hp V4 (Raker prop a good idea?)

[Johny25]

Ok so I ran my boat for the first time today (1989 Spectrum 1900 aluminum) and I tried 2 different props and results are as follows.

With 2 adults and 2 children:
13X19 Stainless (brand unknown? But it is painted black from factory) 5200-5250 RPM at 42mph
13.5X17 aluminum stock prop 5650-5700 RPM at 41mph

Just me in the boat the SS 19 pitch ran 5450-5500 at 44mph (did not run the 17 with just me)

So I am thinking the 19 is just a bit too much prop and I want to keep my RPMs closer to 5500 as I will have people in my boat 98% of the time probably. I want to get an SS prop I was wanting to get a Raker prop but all I see is an 18" pitch available. I am not sure I will get the RPMs out of an 18 that I want. I will also be pulling tubes at times behind this boat so I am thinking a 17 pitch would be the best overall fit. Shouldn't spin a 17 to fast even when lightly loaded I think. Maybe a Raker is not even a prop I should be looking at as I am not going over 50mph anyway? Steelespike are you still on here for some advice

 

[Texasmark]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

On the black painted SS prop, last one I knew of was the OMC SST....aka Stainless Steel Teflon coated; first SS prop OMC produced. Haven' seen nor heard of one in 40 years or so. May be somebody is blowing smoke..............

Don't expect one prop to do everything as you can't expect one boat to do everything. Will not happen. Water toys require a lot lower pitch in the prop to keep the engine where it belongs. Light load requires a totally different setup for the same reason.

Mark

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Well I never said OMC made the 19 pitch SS prop.....I took it off a 76' johnson 135hp I had last year and have no idea who made it. All I can tell is the paint is original factory paint and it is stainless. I realize I will not be able to do everything with one prop but figure a 17" stainless ought to be a good all around choice (even when tubing the kiddos). My be on the upper end of RPM when lightly loaded but should be in the wheel house of RPM range when towing

 

[jestor68]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

If you go the Evinrude site and check out the performance reports, I think you'll see a lot of Viper props being used on your type boat powered by their V-4 motor(as well as others).

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Well I got a really good deal on an unused stiletto advantage 13.25X17 stainless prop so that is going on when it gets here in the mail. Will post results again for future possible readers.

 

[phillnjack2]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Don't take too much notice of the above about the sst from omc being rare, these were about the most common of all
stainless props from omc.. and a very fine prop to have even by todays standards..
not only is not a rare prop but they still make them today called the sst 2, the 2 means it has added cup.
On the original props after a while the Teflon wears off and many people polish them up.
here is mine.
The Teflon had started to come away and rust coming through so I decided to polish it up and make it look nice.
the most popular size is the 13x19.
They came with the omc bronze converging ring attached.
anyway here is mine before and after polishing it. its about halfway polished as I want to get it looking like a mirror.
I think you will agree it looks better as a stainless semi shiny prop than it did when rusty Teflon.
.

 

[Texasmark]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Don't take too much notice of the above about the sst from omc being rare, these were about the most common of all
stainless props from omc.. and a very fine prop to have even by todays standards..
not only is not a rare prop but they still make them today called the sst 2, the 2 means it has added cup.
On the original props after a while the Teflon wears off and many people polish them up.
here is mine.
The Teflon had started to come away and rust coming through so I decided to polish it up and make it look nice.
the most popular size is the 13x19.
They came with the omc bronze converging ring attached.
anyway here is mine before and after polishing it. its about halfway polished as I want to get it looking like a mirror.
I think you will agree it looks better as a stainless semi shiny prop than it did when rusty Teflon.
.

I had a '72 125 Johnny and every time I went out I'd come home with a dinged prop. In '73 they came out with the SST at $185. I had a time raking up the money with 4 kids and all but did and was well worth the money. The pitch was either 17 or 19, don't remember but it was on an 18' FG Caravelle and there were 6 of us that enjoyed skiing. Was probably the 17.

It pushed the boat right at 39 with a light load. I remember the number because I "lusted in my heart" (Jimmy Carter confession) for the number 40 but to upgrade pitch just for that was a waste of money (which was tight at the time) and a lot of make work to change the prop depending on what we were going to do. I assumed at the time that the Teflon coating was to prevent what you showed in your pics: Rust. I guess their SS was a low grade and had a lot of carbon and little nickel in the recipe.

Mark

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Don't take too much notice of the above about the sst from omc being rare, these were about the most common of all
stainless props from omc.. and a very fine prop to have even by todays standards..
not only is not a rare prop but they still make them today called the sst 2, the 2 means it has added cup.
On the original props after a while the Teflon wears off and many people polish them up.
here is mine.
The Teflon had started to come away and rust coming through so I decided to polish it up and make it look nice.
the most popular size is the 13x19.
They came with the omc bronze converging ring attached.
anyway here is mine before and after polishing it. its about halfway polished as I want to get it looking like a mirror.
I think you will agree it looks better as a stainless semi shiny prop than it did when rusty Teflon.
.

That is the exact prop I have so I am assuming mine is an SST also. And being that I pulled it off a 1976 V4 135hp it would make sense

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Ok so my Stiletto advantage 13.25X17 showed up a few days ago and I got to run it today. And this is what I got numbers wise.

5340 RPM at about 42mph.... (had a full load in boat though) which doesn't seem correct as that is a very low slip. Speedometer even bounced off 43 a few times. (I took it off fairly quick and didn't run it alone with light load due to vibration issue)

I was surprised that it runs about the same RPM as the SST 19 pitch and expected to be over the 5500 threshold.

Cons: This prop vibrates very bad at low RPMs and doesn't pan out until about 2500-3000rpm which I do not like at all. The SST and aluminum prop I had on did not vibrate like that at all. Even put the SST back on and the vibration went away immediately. The Stilletto prop has 3 vent holes and did not come with the plugs....not sure if this is what could cause the low RPM vibration or not but I plan to fill the vent holes before trying it again.

Pros: The Stilletto grips way better fully trimmed than the SST or aluminum prop. Matter of fact I can raise motor to full trim and not blowout. Probably due to the more aggressive cup on the blade tips. The SST blows out very easy comparatively and can't be raised very high.

I am not very happy with the Stilletto to be honest...the vibration is intolerable at low speed and has to be fixed or I am selling prop asap. Any advice is welcomed.....take it to prop shop maybe?

 

[jimmbo]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

post retracted

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Well I dropped the prop off at precision propellor to get balanced and worked. Going to take a little cupping out so its not as aggressive. Will post results in a few days when I get it back

 

[Texasmark]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Looking at the pics phil supplied of the SST there is very little cupping. Cupping helps you to hold better as you stated with your Stiletto and will act as a pitch increase at the higher rpms which will account for some of the loading you are getting that you didn't expect with the S. Apparently your S has an aggressive cup.

The ports in the prop are for hole shot. Your SST and probably alum were not ported. They have to be sized for your boat/setup. No holes means long hole shots with a lot of engine loading if running a prop that is pitched to max out your top end mph.....ports make the hole shot act like a low pitched prop in the hole shot giving you fast rpms and good hp development, aka a fast shot. Holes too big means that there is too much bypass exhaust over the blades and it makes the prop ventilate excessively and again long hole shots, but this time the engine rpms are excessive. The right size plugs and you have a nice strong and fast hole shot and the rpms settle down just after you pick up speed from the shot after planing out.

If the prop shop checks the balance of your S and the hub for balance and roper installation then they probably can tell you where to get some plugs so that you can experiment and get the right size. All holes need to be the same size. In desperation, just epoxy them shut...JB weld works.

HTH,
Mark

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Thanks Tex.....and yes the SST has very little cupping compared to the Stilleto. And the vent holes are all the same size (about the size of a pea or a touch bigger). I am picking prop up this morning and may try and test it today, will post results

 

[Johny25]

Re: 1993 Johnson 120hp V4 (Raker prop a good idea?)

Test results after having the cupping ground out of it.......5750-5820rpm at 43.5mpg GPS.....my speedometer read close to 45 but the GPS is likely more accurate