Prop help

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More2LifeThanMPG

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« on: May 27, 2016, 07:22:10 PM »
So I know, gone to the dark side... Haha

But I have an 86 Howard 21' River Cruiser, it has a Mercruiser 350 backed up by an alpha 1 drive. It currently has a 5 blade torque prop that has some serious hole pull. But I'm thinking about switching up props, or a least having a good usable spare. Anyone have any recommendations or anyone care to school me a prop pitch? I'm not looking for seriously performance, but I'm thinking I'm leaning more towards mid to high range power than low end.

From what little research I have done, it seems to be all over the board as to what to start with. And I'd like to not have to buy and trade 15 times before finding the right one.


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vwagon13

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« Reply #1 on: May 27, 2016, 09:19:04 PM »
What pitch is it now? How many horsepower you estimate now? How many rpm now. How "tight"can you turn the motor. What's the gearing on the Alpha now?
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GT Jets

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« Reply #2 on: May 27, 2016, 09:47:07 PM »
Carbureted 350? 260 hp?

Your drive should be a 1.50:1.

Depending on the weight of the boat, a 19" pitch with  a diameter of 15 1/4" diameter will be a great all around prop. Decent out if the hole,  probably turn about 4,800 rpm at WOT.

A 21"pitch will give you more mile an hour,  but take more time out of the hole.

I have like 15 stainless props.  Cleavers, choppers, round ear,  High Fives,  all kinds of goofy stuff.

By far,  the best prop for our cruiser was a 21" pitch 15" diameter chopper..


What pitch is on it now?

How much HP?

What rpm does it turn flat out?
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
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If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

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« Reply #3 on: May 28, 2016, 10:07:20 AM »
I'm not sure of the current pitch, it's a 5 blade with zero marking on it.

Rpm- no idea haven't been able to run it full out have been having timing issues, that should now be figured out. Guy had it set 46* all in, and the motor would die after 3k. I believe we are now at 34* all in.

Hp- yes it's the 350, 260hp. Has a quadrajet currently only upgrade that I can tell is new the new ignition items I put on (hei dizzy, wires, and plugs).

Alpha, yes the 1.50 gearing.




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« Reply #4 on: May 28, 2016, 10:34:38 AM »
I'm not sure of the current pitch, it's a 5 blade with zero marking on it.

Rpm- no idea haven't been able to run it full out have been having timing issues, that should now be figured out. Guy had it set 46* all in, and the motor would die after 3k. I believe we are now at 34* all in.

Hp- yes it's the 350, 260hp. Has a quadrajet currently only upgrade that I can tell is new the new ignition items I put on (hei dizzy, wires, and plugs).

Alpha, yes the 1.50 gearing.




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Wish you still had the Thunderbolt on it. The curve in those is literally spot on.

If it's a high five the ID is in the hub by the nut.

Not all hulls can take advantage of the five blade,  but it will come out of the hole like an animal.

The quad on that is an 820cfm marine deal,  your going to be hard pressed to find something that works better.

I would try a 14-3/4" diameter by 21" pitch Bravo stainless if you can find someone to borrow one from.

On your Quadrajet, on the secondaries, there is a clock spring with a screwdriver slot on the trunion retained by a small either Torx or Allen screw. 

This adjustment is rarely correct. I will get you the proper spec when I get a few minutes this afternoon. The factory adjustment normally leaves about 25 hp on the table (like 150rpm).

Also too, I can't stress the importance enough on keeping a good impeller in the drive,  good flappers in the exhaust pipes and keeping the shaft alignment proper,  all these items should be checked and replaced at the beginning of each boating season,  if you use it or not.

You should be able to run that motor at about 5,000rpm, but it makes more power/torque at 4,800, so plan your prop to get to about that point,  a 21 will get you to about 4,700 rpm if the tune is close (at sea level of course).

Also,  this gets screwed up all the time,  new lock tab washer every other time and torque the nut to 60 foot pounds. You can use a 2x4 between the propeller blade and the cavitation plate to help you run it down.

Another quickie,  make sure there is oil to the upper screw in the drive,  just like setting the floats on a Holley carburetor. Just 1/2" too low will smoke the upper bearing.

I normally install a remote reservoir kit if it don't already have one.

GT
« Last Edit: May 28, 2016, 10:53:58 AM by GT Jets »
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

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« Reply #5 on: May 28, 2016, 10:50:50 AM »
Yeah..... you know, I would get the engine running sweet first, that 46 degrees is way too much as you found out. 34 - 36 is what that Chev y would like.
 Then you could start on your prop. You might find out that current propeller works out good for you with a good running motor.

 And follow GT's advice , good stuff  for sure.
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« Reply #6 on: May 28, 2016, 11:45:55 AM »

Wish you still had the Thunderbolt on it. The curve in those is literally spot on.

If it's a high five the ID is in the hub by the nut.

Not all hulls can take advantage of the five blade,  but it will come out of the hole like an animal.

The quad on that is an 820cfm marine deal,  your going to be hard pressed to find something that works better.

I would try a 14-3/4" diameter by 21" pitch Bravo stainless if you can find someone to borrow one from.

On your Quadrajet, on the secondaries, there is a clock spring with a screwdriver slot on the trunion retained by a small either Torx or Allen screw. 

This adjustment is rarely correct. I will get you the proper spec when I get a few minutes this afternoon. The factory adjustment normally leaves about 25 hp on the table (like 150rpm).

Also too, I can't stress the importance enough on keeping a good impeller in the drive,  good flappers in the exhaust pipes and keeping the shaft alignment proper,  all these items should be checked and replaced at the beginning of each boating season,  if you use it or not.

You should be able to run that motor at about 5,000rpm, but it makes more power/torque at 4,800, so plan your prop to get to about that point,  a 21 will get you to about 4,700 rpm if the tune is close (at sea level of course).

Also,  this gets screwed up all the time,  new lock tab washer every other time and torque the nut to 60 foot pounds. You can use a 2x4 between the propeller blade and the cavitation plate to help you run it down.

Another quickie,  make sure there is oil to the upper screw in the drive,  just like setting the floats on a Holley carburetor. Just 1/2" too low will smoke the upper bearing.

I normally install a remote reservoir kit if it don't already have one.

GT

Carb- I've been told that about the quad a couple times, and I will have to check the secondary adjustment.

Prop- I will attempt to swing by storage and check inspect for any id'ing marking. Also someone told me about a prop shop in Havasu that you can rent them by the day for, so I'll have to check into it.

Maintenance- thank you and I am aware of the yearly drive care.

When you say lock tab? I'm a little confused as to what you are referring to.

And I will look into the reservoir, I was also informed a drive 'shower' would help.


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« Reply #7 on: May 28, 2016, 12:18:45 PM »
Carb- I've been told that about the quad a couple times, and I will have to check the secondary adjustment.

Prop- I will attempt to swing by storage and check inspect for any id'ing marking. Also someone told me about a prop shop in Havasu that you can rent them by the day for, so I'll have to check into it.

Maintenance- thank you and I am aware of the yearly drive care.

When you say lock tab? I'm a little confused as to what you are referring to.

And I will look into the reservoir, I was also informed a drive 'shower' would help.


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What year drive?  I have a trick that blows the performance of the showers out of the water.

The lock tab for the prop nut,  the are made of stainless and should be replaced every two or three times they are set.


GT
  • Boat #1: 1992 Carrera 20.5 Elite (I/O bitches)
  • Boat #2: 19' Bubble deck Jet BBC Berkeley
If i get some free time tonight at work, ill play with it and post it for everyone to see.

Time to man up and yank it John!  :banghead:
Ray

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« Reply #8 on: May 28, 2016, 08:24:02 PM »
Hey more to live I have a 3 blade 19P quick silver prop you can have I have known use for it I'm in the I.E.


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« Last Edit: May 30, 2016, 01:33:17 PM by placecraft jess »

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« Reply #9 on: May 28, 2016, 10:03:49 PM »

What year drive?  I have a trick that blows the performance of the showers out of the water.

The lock tab for the prop nut,  the are made of stainless and should be replaced every two or three times they are set.


GT

I would assume it's an 86 like the hulk an engine. With that said I was looking at the prop when we were swapping out the dizzy and setting the timing, it doesn't appear there is a locking nut ok the hub. It appears to be a different style lock. I'll take a couple pictures when I get over there.


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« Reply #10 on: June 13, 2016, 06:59:37 AM »
So I finally remember to take a couple pictures. I was unable to locate any marking other then a us pat # though.

And here is what the pat number references.
http://binged.it/1ULxbTy


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« Reply #11 on: June 13, 2016, 07:04:08 AM »
There is also a what appears to be a random set of numbers. The spacing is weird, almost like a part number.


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« Reply #12 on: June 13, 2016, 08:23:27 AM »
There is also a what appears to be a random set of numbers. The spacing is weird, almost like a part number.


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19 pitch High Five Prop. Should be nasty as hell out of the hole... Lots of stress for an alpha drive

Your locknut is that, a locknut. Simialr to a wheel lock... Probably made by mcgard. I hope you have the key somewhere

Beig a 5 blade i would imagine you would lose some RPM over a 3 blade of the same pitch.

The bahner we run a 19" 3 blade when tubing and stuff. Its great out of the hole. And decent enough on the top end. A 21" 3 blade when we are just cruising around and going far distances.

Approx 350-400 hp deal. Heavy ass boat
1980 Bahner 21' Mini Day
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« Reply #13 on: June 14, 2016, 01:51:58 PM »

19 pitch High Five Prop. Should be nasty as hell out of the hole... Lots of stress for an alpha drive

Your locknut is that, a locknut. Simialr to a wheel lock... Probably made by mcgard. I hope you have the key somewhere

Beig a 5 blade i would imagine you would lose some RPM over a 3 blade of the same pitch.

The bahner we run a 19" 3 blade when tubing and stuff. Its great out of the hole. And decent enough on the top end. A 21" 3 blade when we are just cruising around and going far distances.

Approx 350-400 hp deal. Heavy ass boat

Ha, helps if you don't put the dots in there. Thanks!

And yes it's a monster out of the hole, pulls as well as my dads v-drive ski boat! And I'll be able to get some real numbers this weekend.

I'd really like to pick up a good spare prop too.


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« Reply #14 on: June 20, 2016, 11:04:01 AM »
Placecraft Jess an GT Jets - tried messaging both of you but not sure the are going through.
Can you guys get in touch with me please. Glenn I lost your number on my last phone.
Thanks Frank.
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« Reply #15 on: June 20, 2016, 11:21:50 AM »
What year drive?  I have a trick that blows the performance of the showers out of the water.

The lock tab for the prop nut,  the are made of stainless and should be replaced every two or three times they are set.


GT

 Hey Gt.I've got a later 70's, early 80's Alpha I on my 'toon. Tell me about your shower trick. My drive does get pretty warm. Thank you.👍
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« Reply #16 on: June 21, 2016, 06:09:24 PM »
So went out this weekend and did a couple tests, she running full of fuel with all stuff and 6 people at a solid 39... 😐

Only ran a little harder with nearly empty tanks and 4 people at 41, but would be a solid 4700 rpm all in. It took a little to find the sweet spot and it wasn't the smoothest water.

So I'm a little bummed at the overall performance, but even the current five blade could use some work. It's not sharp at all.

Also the none baffled glass tanks are a little annoying when it is under a half tank.


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« Reply #17 on: June 21, 2016, 06:25:13 PM »
So went out this weekend and did a couple tests, she running full of fuel with all stuff and 6 people at a solid 39... 😐

Only ran a little harder with nearly empty tanks and 4 people at 41, but would be a solid 4700 rpm all in. It took a little to find the sweet spot and it wasn't the smoothest water.

So I'm a little bummed at the overall performance, but even the current five blade could use some work. It's not sharp at all.

Also the none baffled glass tanks are a little annoying when it is under a half tank.


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I'm sure you are. But were you trimming it up?
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« Reply #18 on: June 22, 2016, 09:25:18 PM »

I'm sure you are. But were you trimming it up?

Yes sir, all the way until is starts to porpoise. Then a tad back down.


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« Reply #19 on: June 22, 2016, 09:31:12 PM »
Yes sir, all the way until is starts to porpoise. Then a tad back down.


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Something isn't right. That RPM with a 19 pitch prop should be mid 50s at least.

You have a massive amount of prop slip. Trimming down didn't help?

Check this propeller calculator out.

I'd this thing stupid heavy?

http://www.go-fast.com/Prop_Slip_Calculator.htm
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« Reply #20 on: June 24, 2016, 06:38:47 AM »

Something isn't right. That RPM with a 19 pitch prop should be mid 50s at least.

You have a massive amount of prop slip. Trimming down didn't help?

Check this propeller calculator out.

I'd this thing stupid heavy?

http://www.go-fast.com/Prop_Slip_Calculator.htm

Trimming down helped slightly by the seat of your pants, but nothing in numbers.

That's kinda what I was hoping someone would say because that's an easy fix for more mph. I was given some information on a company locally that came highly recommended for prop work, so I'll give them a call.

And yes I'd say she is pretty heavy, in addition I was carrying a lot of stuff.


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« Reply #21 on: November 11, 2017, 12:06:32 AM »
Get a 3 blade


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