Have i wasted my money?

[Frank Acampora]

Re: Have i wasted my money?

Well, Mark---I am a regular at the Chrysler Crew forum! My first "big" engine was a Chrysler 55. I bought it new for 600 bucks with 1 tank and controls. That little 2 cylinder outran the 3 cylinder 55 Rudes and I kind of got stuck on brand loyalty. Up until a few years ago, I wouldn't buy anything except a Chrysler built auto. I usually got a few hundred thousand miles out of them.

Like anything else, different people have different luck and opinions.

I'll be the first to admit that I have lunched a couple of Force and Chrysler engines but by far, the fault was mine--either taking a shortcut or using a substandard part. However, these were my personal engines and I went into it knowing the risk. For example: on one 125 HP engine I used a crank with mild etching on one crankpin. At the time I could not find a better crank and I knew service life would be less than expected. It lasted for two seasons and then went south--but again, I sort of expected it to.

I only rebuild by recommendation or word of mouth, and even then, only about 2 a year. After all, It is only my hobby. When I rebuild for someone else, (or for my main boat which will be frequently used, and must get me back home) I go by the book and am reasonably certain that the repair is quality and the engine will give good service to the owner. I pride myself on workmanship and sometimes remark that the engines leave my hands in better than factory new condition. While I will not give a guarantee, if something was to go wrong in a short period through no fault of the owner, I would probably make it right.

Right now I have about 15-17 Chrysler and Force engines in various sizes from 4 to 140 HP and something like 6 extra stainless props plus 4 or 5 aluminum and a few bronze--I guess I'm a collector of underdogs. Most of the big ones are 17,19, and 21 pitch.

Oh, yeah! To even things out and show I'm not predjudiced, I also have a Merc "tower of Power" 115.--But I usually don't like to let that slip out in conversations.

All my engines run and by the way: I still have that 1969 55. --Did have to rebuild it this year though.

So: It would take a lot to "rain on my parade"

 

[walleyehed]

Re: Have i wasted my money?

Not my rule of thumb from what I've found.

This is all a moot point anyway, I've done it all these ways, and still come to my same conclusion 200rpm between prop pitch changes, which happen to be in increments of 2", not 1". Unless you're talking about 4blade, or multiblade props, of which some do come in increments of 1".


Your repeating yourself here, that doesn't make it necessarily so, In due respect, you believe what you want, and I'll believe what works for me, and the bottom line is, I've never physically seen a 400 rpm raise, or drop, by changing one normal increment of pitch, hence 2"

Have you run or tested almost 600 different props in 2 years?
Do you have digital shop tachs as well as in-dash?
How many GPS units do you use?
Do you have EGT, CHT and Shaddin fuel flow meters???
I do......
When dealing with ONE manufacturer's design in pitches changing at 2" increments, and running a prop of a given pitch with a MEASURED load, then re-fill the tank and repeat step #1 with the same design and 2" more pitch, the result is almost ALWAYS 350-450RPM...2".
The ONLY time I see anything different is when an engine is propped for the low end or below the recommended range, in-which case the RPM can jump 500-600 in 2" drop in pitch, and on 4-strokes, I have seen 800 increase in 2"
By the way, there are plenty of props out there in 3 or 4 blade with even and odd numbers.....do some research.

 

[MikDee]

Re: Have i wasted my money?

Wow -- I didn't realize someone could get so opinionated over a "rule of thumb". My gosh it's a rule of thumb, not the eleventh commandment. First, I wasn't repeating myself -- that last quote was from Caravelle Power Boats but I suppose they don't know what they're talking about either. Here's another:
marine-outboards.com/choosing-propeller.htm.

I agree with you that three blade props "generally" change pitch in 2-inch increments. But that's not ALWAYS true either! Look up this number 5034754_5034755 on iBoats and there are other examples as well if want to take the time to look. You'll find it's a 22-1/2 inch pitch three blade. And this one (345041) is a rather common Ballistic 22P three blade. Even the prop manufacturers use the 150 - 200 rpm per inch (not 2-inches) number in their prop recommendations. It the rule of thumb doesn't work for you I can't help that. It seems to work for the majority of us.

Opinionated Yes! but I didn't put you down! there's no reason to come down on me. All I did was disagree with you in a respectful manner. I just broke up your statements, to make it easier to give my point of view?, no it's not the "11th commandment" and I didn't make it out to look that way! and that last statement you claim was from Caravelle boats, was not quoted, or bracketed, so I just figured you were repeating yourself?

 

[MikDee]

Re: Have i wasted my money?

Have you run or tested almost 600 different props in 2 years?
Do you have digital shop tachs as well as in-dash?
How many GPS units do you use?
Do you have EGT, CHT and Shaddin fuel flow meters???
I do......
When dealing with ONE manufacturer's design in pitches changing at 2" increments, and running a prop of a given pitch with a MEASURED load, then re-fill the tank and repeat step #1 with the same design and 2" more pitch, the result is almost ALWAYS 350-450RPM...2".
The ONLY time I see anything different is when an engine is propped for the low end or below the recommended range, in-which case the RPM can jump 500-600 in 2" drop in pitch, and on 4-strokes, I have seen 800 increase in 2"
By the way, there are plenty of props out there in 3 or 4 blade with even and odd numbers.....do some research.

Walleyhed, I don't think you need to reinforce this issue, No I'm not a prop expert, but it sounds to me like you are? I'm just your average backyard boater, with experience learned from owning, & wrenching on a lot of boats over the yrs, but sometimes it's hard to recall certain exact details, but I intend to go back over my information, and research this further, all I did was give my opinion, and try to help. I apologize to davis 7210 if I've given any wrong information, I guess he'll have to try the new prop, and see what his results are.

 

[Don S]

Re: Have i wasted my money?

I guess he'll have to try the new prop, and see what his results are.

That is the ONLY thing you can do with a prop to find out what is going to actually happen.
You can estimate and make WAG's or even educated WAG's, but you still are only guessing and calculating. When you get out on the water it's a whole new ball game.
Who here knows if he has the boat trimmed properly, or if the boat is water logged, overloaded (seriously stern heavy), or the waves are a 3 foot chop and running into a head wind with current, and trying to do a WOT test. No one knows, and it would only take one of the above problems to kill rpm.
Surprisingly, no one even mentioned he also increased diameter by 1/2". Which is about the same as increasing the pitch a 1/2"

 

[alphaboat]

Re: Have i wasted my money?

I wanted to jump in here as I have a related issue.
Just purchased a new 60HP Mercury 4-stroke to replace my 50HP 2-stroke on my 17' Alumiweld center console.
Recommended WOT for new engine is 5500 - 6000 RPM
Outboard came with 10.62 X 12 pitch which ran out at over 6000 RPM WOT
So I went to 10.50 X 13 that still hits 6000 RPM (overspeed alarm sounds intermitantly) when I am alone in the boat but loaded with normal fishing gear, anchor, fuel, etc. Performance with this prop is quite good with a good hole shot and top end speed of about 32 MPH @ 6000 with 0-30 of about 11.5 seconds.
I then tried a 10.25 X 14 with boat load identical and got about 5750 RPM WOT. Hole shot felt more sluggish - 0-30 about 15.5 seconds but top end speed is 36 MPH at 5750

All props tested were Mercury Black Max Aluminum

I haven't had an oportunity to try testing these props with another one or two persons aboard. My experience with the previous motor (50HP 2-stroke) was that I could feel the difference in the hole shot but that WOT would not be greatly affected by the added load. Should I expect a difference with the 4-stroke?

Anyway, I am leaning towards going to a prop shop and having them "tweak" a stainless wheel to 13.5 pitch.
Any comments regarding that plan?

 

[davis7210]

Re: Have i wasted my money?

Finally got to get boat in water today!!! so here we go, at 5600 rpm wot in very choppy water i ran 44.1 mph GPS. This new prop got me 600rpm!! I think i may raise the motor up 1 hole, i was able to use a lot of trim!!! Hole shot was great, it would jump up,turn some r's then hook!!! Made about 15, 1/2mile runs wind started blowing about 15mph time to take it to the house! Got back to dock and played rescue boat, old gentleman's boat quit had to tow him back. Glad to help might need tow myself one day. Again thanks for all replies i have learned much, and now i can see results!!

 

[MikDee]

Re: Have i wasted my money?

Well Good For You So, I guess I was right then, with what I posted previously.

 

[Silvertip]

Re: Have i wasted my money?

By golly I guess the rule of thumb worked again eh? 4-inches of pitch at 150 RPM per inch = 600 RPM.

 

[walleyehed]

Re: Have i wasted my money?

If we consider the 21 was an SST (SS) it was more efficient, as expected, and the 17 is alum?...so 150 per inch is good. Pitch down, diameter usually goes up which can hold it back a tad farther. and it didn't stop at 5400...Hummmmm...

 

[MikDee]

Re: Have i wasted my money?

By golly I guess the rule of thumb worked again eh? 4-inches of pitch at 150 RPM per inch = 600 RPM.

Not according to your original statement 4" @ 200rpm per inch of pitch = 800rpm, that's what you were trying so hard to prove, plus this doesn't even really apply because, he went from a stainless prop to an aluminum prop, which would add about 100rpm as I figured, 100rpm + 800rpm = 900rpm
You can't have it both ways to suit yourself, I was closer!

 

[walleyehed]

Re: Have i wasted my money?

It would only add 100 if the prop was in like-new condition.
If the prop has some wear and/or damage, it would subtract 100-150 from the total figure, and again, only if he stays with the same design.
Bottom line is to test.....the only way to know for sure.
I have 17P props that run the same as another in 19P, and yet a 15P Turbo the same as a 19P in aluminum. There is no rule when you change brands/design.
Might be best to wish the original poster good luck, glad it worked if that's the rpm he's looking for and leave it at that. We are here to help, add our 2 cents and continue to do so if needed. We are not here to tell anyone they are full of whatever. This being said, if we have nothing to add to the original poster's questions, it's time to drop the subject.

 

[Silvertip]

Re: Have i wasted my money?

What part of "rule of thumb" don't you understand Mik! Rule of thumb is an approximation. Heck, a half tank of gas on one run vs a full tank on the next can account for 50 RPM as can a change in the weather or water conditions. And just so there is no more confusion, I did quote myself.

Actually, the rule of thumb is one inch of pitch up or down = 150 - 200 RPM up or down. So a four inch drop in pitch would net about 600 - 800 RPM not 400. But again, all of that depends on the design of the existing prop and the design of the replacement. Pitch is only one factor. You can also gain rpm by playing with engine mouting height. Just don't go so high that you lose water pressure before the prop begins to lose bite.

 

[jay_merrill]

Re: Have i wasted my money?

Just to illustrate the importance of blade material and prop design on rpm changes, when going from one wheel to another, consider this - I had a 15" pitch Michigan Match, 3 blade aluminum wheel on my 65hp Johnson. I just put a 15" pitch, 3 blade, cupped SS wheel of the same diameter on the motor. With an identical load in the boat, right down to fuel on board, the motor now runs 100 - 125 rpm higher at WOT.

 

[MikDee]

Re: Have i wasted my money?

I have found that any boat of mine with a Mercruiser, gained more rpm, & speed with a stock Alum. Merc. Black Max prop, then the same pitch Alum. Michigan wheel, but that's not saying much.

 

[Texasmark]

Re: Have i wasted my money?

Boy I certainly don't want to be partisian to this exchange, but I have a tad of fodder.

Was out today in just above freezing weather. Got my 50 gps out of my little piece of crap boat (which I just paid for......all mine....smile) and 90 Merc with the 24P Ballistic. Thumped my face a couple of times and felt nothing. Had to turn south and cut the throttle and walla.......all of a sudden I was hot.....hot like frost bite? I guess.

Regardless, having changed nothing, I noticed that my little hot dog is ventilating a lot more than it did the last couple of years. Rather than locking into the 5600 it liked at 50 GPS, it now seems to like 5900 and on a couple of runs (I put safety goggles on so that I could see without my eyes watering) it punched up to 6200.

But the real news is, today was the second day of a norther and the fish had lock jaw, but the wife and cleaning lady were working the house over and I resolved myself to be long gone during that escapade......but I clean up after myself, do laundry, dishes, and pick up my stuff....so I'm no slob.

Mark

 

[Texasmark]

Re: Have i wasted my money?

Well, Mark---I am a regular at the Chrysler Crew forum! My first "big" engine was a Chrysler 55. I bought it new for 600 bucks with 1 tank and controls. That little 2 cylinder outran the 3 cylinder 55 Rudes and I kind of got stuck on brand loyalty. Up until a few years ago, I wouldn't buy anything except a Chrysler built auto. I usually got a few hundred thousand miles out of them.

Like anything else, different people have different luck and opinions.

I'll be the first to admit that I have lunched a couple of Force and Chrysler engines but by far, the fault was mine--either taking a shortcut or using a substandard part. However, these were my personal engines and I went into it knowing the risk. For example: on one 125 HP engine I used a crank with mild etching on one crankpin. At the time I could not find a better crank and I knew service life would be less than expected. It lasted for two seasons and then went south--but again, I sort of expected it to.

I only rebuild by recommendation or word of mouth, and even then, only about 2 a year. After all, It is only my hobby. When I rebuild for someone else, (or for my main boat which will be frequently used, and must get me back home) I go by the book and am reasonably certain that the repair is quality and the engine will give good service to the owner. I pride myself on workmanship and sometimes remark that the engines leave my hands in better than factory new condition. While I will not give a guarantee, if something was to go wrong in a short period through no fault of the owner, I would probably make it right.

Right now I have about 15-17 Chrysler and Force engines in various sizes from 4 to 140 HP and something like 6 extra stainless props plus 4 or 5 aluminum and a few bronze--I guess I'm a collector of underdogs. Most of the big ones are 17,19, and 21 pitch.

Oh, yeah! To even things out and show I'm not predjudiced, I also have a Merc "tower of Power" 115.--But I usually don't like to let that slip out in conversations.

All my engines run and by the way: I still have that 1969 55. --Did have to rebuild it this year though.

So: It would take a lot to "rain on my parade"

Like you said we're here to have fun.

I may have misquoted myself previously, but in '71 I started out with the 16' Sport Fury with the '55 (may have said 45 hp) and within a few months I was trading for the '85 and obviously lost my shirt in the process. Then lost my shirt on fuel economy. Kept the boat for a year and traded for a '72 Caravelle with a 125 Johny......great decision.

Funny all my friends at the time had 3 cylinder OMC's and were doing a tail wag around me. I couldn't wait to get out from under that gas sucking thing which, by the way, had the first prop (which looked really cool, buttt) that I ever had that suffered from real life cavitation erosion.


Mark