SUCCESS!!! (But I do have a couple of questions ...)

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
First time boat owner, here. It's a '76 850. I bought the boat a few months back and have been working on it ever since. I didn't know jack squat about 2 cycles, so I had to learn along the way. I had to fight just to get it started, and it ran pretty sad. It wouldn't get over 5mph without stuttering before stalling, and it had a terrible miss. Gaskets and bottom crank cap seals were shot. Had to replace the bottom crank cap seals, transfer port cover gaskets, exhaust plate/outer jacket/inner jacket gaskets (that was a nightmare), and cylinder cover gasket. New set of plugs, and both carbs were rebuilt. I also replaced the water pump. Before all the work, and when I was able to get it running, it ran hot. Pee-hole stream was scalding, and you couldn't lay hands on the engine. It was extremely difficult to get it restarted.

I finally performed the link/sync on it, today. Amazing how these engines run when the carbs and timing are set just right. It runs great and cranks right up. Actually, it cranks pretty easy for the first start of the day. The hole shot is pretty awesome. It gets right up there. It runs much cooler, too. The pee-hole stream is warm (not scalding, anymore), and you can actually lay hands on the engine without getting burnt. My wife and I had it out on Lake Washington here in Seattle, today, and this is the first time we were able to actually enjoy the boat. I couldn't have gotten this far without input from this forum, and I really do appreciate all the help everyone has given me so far.

Now, here comes the questions:

1) After replacing the impeller, it appeared to have a steady, strong stream during idle. Now, at idle, it appears like a weak drip until I increase the RPM's, and then it comes out in a stream although not like it used to right after replacing the impeller. Is this normal? I can blow back through the pee-hole, and I can hear it gurgling down in the lower unit around the impeller, so I know there aren't any blockages. Additionally, it doesn't run hot. I can put it in gear and turn the prop by hand, and the sound of the new impeller sounds the same now as when it did right after replacement. So, that tells me the impeller is still good and turning, in my opinion. I know one isn't absolutely positive about anything unless it's inspected. I'm wondering if the slip-tube that joins the long tube to the water pump became disconnected somewhat or something to that effect. Maybe I'm just being paranoid.

2) My top speed was 30 mph measured using GPS. I was hoping to get it to at least 35.
- The prop has a 15P stamped on the end of string of numbers, so I'm assuming the pitch is 15? It's a 3 blade 14(?)" diameter prop.
- The boat is a 1978 15' Bramco Seaswirl trihull.
- Only my wife and I were in the boat, and I had my tool bag (approx. 30 lbs).
- Lake Washington was real choppy, and boat was hitting the waves pretty hard.
- The boat doesn't have a tach (yeh, I know, I need to get one), so I really don't know what the top end RPM's were. It was up there though.
- The previous owner included a load of ski ropes, so I'm assuming that was his main purpose in using it.
- The boat pulls hard to starboard, so I assume the anode needs adjustment.
Can someone calculate what size prop this engine should have, and can I assume the 15 pitch prop was used to get up to speed, faster, because it was pulling a skier? I'm wondering what size prop I should have that would be a good fit for skiing and top speed. Finally, would a real choppy (big) lake and hitting these waves cause it not to reach the actual top speed?

As always, all input is appreciated.
 
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Bill kubiak

Chief Petty Officer
Joined
Jan 31, 2004
Messages
629
Hey milbinseattle,
What's the haps?? Yup you gotta get a tach, you also gotta know what is the top end RPM's for that motor and you need a prop that lets you get there, if at WOT you cannot get top end RPM's you have a prop with too much pitch and if you over rev you have a prop with too little pitch,
TIP: if you have a Cupped Prop that add's a little more then 1 degree of pitch but it also helps to prevent prop slip

DO you have a trim tab on that motor? if so give it a little tilt to starboard to off set that pull, the boat should go straight ahead at full speed with no pull in any direction hence the need for a trim tap, anode (Turning the tab to starboard push's the motor to the left a little turning the boat to the left)

I am gonna go get my Miami Dade County senior citizen ramp permit today so I get 13 months for the price of one year. the ramps here now charge 15.00 a launch and per day with a permit I can go out and stay out for a week and not get hit with that extra day fees, I think threatened around 70.00 a year for the permit, so I gotta use it at least 5 times a year to break even after that it's free.......it's good at any county park or county ramp.
 

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
Hey milbinseattle,
What's the haps?? Yup you gotta get a tach, you also gotta know what is the top end RPM's for that motor and you need a prop that lets you get there, if at WOT you cannot get top end RPM's you have a prop with too much pitch and if you over rev you have a prop with too little pitch,
TIP: if you have a Cupped Prop that add's a little more then 1 degree of pitch but it also helps to prevent prop slip

DO you have a trim tab on that motor? if so give it a little tilt to starboard to off set that pull, the boat should go straight ahead at full speed with no pull in any direction hence the need for a trim tap, anode (Turning the tab to starboard push's the motor to the left a little turning the boat to the left)

I am gonna go get my Miami Dade County senior citizen ramp permit today so I get 13 months for the price of one year. the ramps here now charge 15.00 a launch and per day with a permit I can go out and stay out for a week and not get hit with that extra day fees, I think threatened around 70.00 a year for the permit, so I gotta use it at least 5 times a year to break even after that it's free.......it's good at any county park or county ramp.


I'll get a tach before next season. It's too late in the game, this year, for any water skiing, so I really don't have a need to be running it at WOT anymore this year. Probably will take it out during September for some fishing, but that'll be it.

I don't have a trim tab. Just an anode. I read where these Mercs were known for pulling hard to starboard. The anode was turned about 1/8" to the left from center looking at it from the very rear. This points the forward side of the anode toward starboard. I guess I'll need to turn it a little more or just experiment with it.

The max RPM range for my engine is 4800-5500 RPM's. The gear ratio is 2.3:1. Using a simple prop calculator, I entered 5500 RPM's, gear ratio of 2.3, 15" pitch, and 10% propeller slip. It calculated 30.6 mph which is about what I was doing. Using Mercury's prop selector calculator, at 5000 RPM, I'd need a 17" pitch prop to get to 35 mph, and that's for overall performance. For acceleration with top end at 5500 RPM using the prop I have now, it says I should get at least 33 mph. The current prop has a little damage to it ... missing a bit out of one of the blades ... about the size of a nickel. It was like that when I bought it, and I plan on getting it repaired or changed altogether. In any case, I figure that's adding to the slippage. Plus, the hard pounding in a choppy lake plus having an additional person and tools, I figured that affected top end speed as well. In any case, for a 39 year old engine that's seen some abuse in its time, it appears that's it's doing pretty good. I don't plan to run it at WOT all the time. This boat's main purpose was to get us to some good fishing spots. :joyous:

What are your thoughts about the pee-hole stream?
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
This points the forward side of the anode toward starboard.
Wrong way, water flowing over the anode (trim tab) turns the motor not the boat.
 

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
Wrong way, water flowing over the anode (trim tab) turns the motor not the boat.

I realize that. I wasn't talking about the boat. I was talking about the direction of the anode when it's turned. Standing in the rear, of you turn it to the left, it points the front of the anode to the right (or starboard).
 

Fed

Commander
Joined
Apr 1, 2010
Messages
2,457
The boat pulls hard to starboard, so I assume the anode needs adjustment.
The anode was turned about 1/8" to the left from center looking at it from the very rear. This points the forward side of the anode toward starboard. I guess I'll need to turn it a little more or just experiment with it.
Good luck with that.
Wrong way, water flowing over the anode (trim tab) turns the motor not the boat.
 

Bill kubiak

Chief Petty Officer
Joined
Jan 31, 2004
Messages
629
I realize that. I wasn't talking about the boat. I was talking about the direction of the anode when it's turned. Standing in the rear, of you turn it to the left, it points the front of the anode to the right (or starboard).

Standing in the rear you need to turn the rear end of the tab to the right,
 

Bill kubiak

Chief Petty Officer
Joined
Jan 31, 2004
Messages
629
I'll get a tach before next season. It's too late in the game, this year, for any water skiing, so I really don't have a need to be running it at WOT anymore this year. Probably will take it out during September for some fishing, but that'll be it.

I don't have a trim tab. Just an anode. I read where these Mercs were known for pulling hard to starboard. The anode was turned about 1/8" to the left from center looking at it from the very rear. This points the forward side of the anode toward starboard. I guess I'll need to turn it a little more or just experiment with it.

The max RPM range for my engine is 4800-5500 RPM's. The gear ratio is 2.3:1. Using a simple prop calculator, I entered 5500 RPM's, gear ratio of 2.3, 15" pitch, and 10% propeller slip. It calculated 30.6 mph which is about what I was doing. Using Mercury's prop selector calculator, at 5000 RPM, I'd need a 17" pitch prop to get to 35 mph, and that's for overall performance. For acceleration with top end at 5500 RPM using the prop I have now, it says I should get at least 33 mph. The current prop has a little damage to it ... missing a bit out of one of the blades ... about the size of a nickel. It was like that when I bought it, and I plan on getting it repaired or changed altogether. In any case, I figure that's adding to the slippage. Plus, the hard pounding in a choppy lake plus having an additional person and tools, I figured that affected top end speed as well. In any case, for a 39 year old engine that's seen some abuse in its time, it appears that's it's doing pretty good. I don't plan to run it at WOT all the time. This boat's main purpose was to get us to some good fishing spots. :joyous:

What are your thoughts about the pee-hole stream?

That chunk out of a prop is not causing much slippage, what it is doing is causing an out of balance situation which will eventually lead to a bearing failure in the lower unit. You gotta get a tach and get a prop that gets you as close to 5500 RPM as you can get

Yikes went for my senior citizen yearly ramp permit today 107.00 up from 70.00 two years ago, gotta get out of Miami, my brother lives up near Ocala Florida and all the public ramps and parking there are free. That's what tax's are for. I chopped down a dying tree in my yard and got slapped with a 200.00 fine for not getting a 100.00 permit. Miami is really starting to Suck the big one.
 

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
That chunk out of a prop is not causing much slippage, what it is doing is causing an out of balance situation which will eventually lead to a bearing failure in the lower unit. You gotta get a tach and get a prop that gets you as close to 5500 RPM as you can get.

Good to know. I plan on getting the prop repaired or getting a new one real soon. Money's kinda tight at the moment, and the tach will need to wait. Wife was in the hospital seven weeks this summer, and bills have piled up. Ugh.

Yikes went for my senior citizen yearly ramp permit today 107.00 up from 70.00 two years ago, gotta get out of Miami, my brother lives up near Ocala Florida and all the public ramps and parking there are free. That's what tax's are for. I chopped down a dying tree in my yard and got slapped with a 200.00 fine for not getting a 100.00 permit. Miami is really starting to Suck the big one.

Sounds like Seattle. They have a fee for everything, and its getting worse. I can't wait to get out of King County. They charge $12/day for boat ramp fees. Anywhere else, it's only $5.
 
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Bill kubiak

Chief Petty Officer
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Jan 31, 2004
Messages
629
I would not run that prop at WOT, if it ever throws a blade before you can pull the power off you can kiss the lower unit goodbye.
Thinking about taking my boat out for a little test run tomorrow
 

mlbinseattle

Petty Officer 2nd Class
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Aug 1, 2015
Messages
100
I would not run that prop at WOT, if it ever throws a blade before you can pull the power off you can kiss the lower unit goodbye.
Thinking about taking my boat out for a little test run tomorrow

I hear ya. I don't see it throwing a blade, just yet. I'm headed out for a camping trip, tomorrow, and I'll be pulling a couple of granddaughters on a towable. After yesterday getting pounded on Lake Washington, it's still holding up. I'll keep an eye on it. Thing is, people have been waiting for me to get this thing going, and I'll never hear the end of it if I tell them no to any fun stuff.
 

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
I rechecked the extension tube where it connects to the water pump housing. It looked okay. Also, there are no blockages in water flow. Do impellers have a wear-in or break-in where they wear down somewhat after installation? At idle, the stream is a dribble that gets stronger with increased RPM's. Right after installation, there was a strong, steady stream.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,030
Throwing a prop blade will not instantly destroy a gearcase. Unfortunately, lots of props lose blades.

Running with an unbalanced prop is bad for a gearcase, but how bad it is depends on how unbalanced the prop is. If the vibration is noticeable, it is bad enough to warrant immediate change of prop. You should have a spare prop anyway. You may spin the prop hub, and will want to change it to get home. That is a lot faster than a tow....
 

mlbinseattle

Petty Officer 2nd Class
Joined
Aug 1, 2015
Messages
100
Throwing a prop blade will not instantly destroy a gearcase. Unfortunately, lots of props lose blades.

Running with an unbalanced prop is bad for a gearcase, but how bad it is depends on how unbalanced the prop is. If the vibration is noticeable, it is bad enough to warrant immediate change of prop. You should have a spare prop anyway. You may spin the prop hub, and will want to change it to get home. That is a lot faster than a tow....

Thanks, Chris. This is good to know. I'll be on the Columbia River, tomorrow, with much smoother waters than Lake Washington. I'll remember to look out for any vibration.

Any thoughts about what I said about the pee- stream?
 

Bill kubiak

Chief Petty Officer
Joined
Jan 31, 2004
Messages
629
Throwing a prop blade will not instantly destroy a gearcase. Unfortunately, lots of props lose blades.

Running with an unbalanced prop is bad for a gearcase, but how bad it is depends on how unbalanced the prop is. If the vibration is noticeable, it is bad enough to warrant immediate change of prop. You should have a spare prop anyway. You may spin the prop hub, and will want to change it to get home. That is a lot faster than a tow....

Hate to disagree here, but I have seen 3 gear cases severely damaged or outright destroyed by throwing a blade at WOT and under a load either by hitting a rock or letting a damaged blade run to far. The vibration is so great at first most folks get startled and do not react fast enough to get the power off, admittedly they were all larger motors but I would assume the effect is the same on any motor at WOT. I would smooth file any rough edges on a damaged prop and keep the rpm's down below WOT.
 

Bill kubiak

Chief Petty Officer
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Jan 31, 2004
Messages
629
I hear ya. I don't see it throwing a blade, just yet. I'm headed out for a camping trip, tomorrow, and I'll be pulling a couple of granddaughters on a towable. After yesterday getting pounded on Lake Washington, it's still holding up. I'll keep an eye on it. Thing is, people have been waiting for me to get this thing going, and I'll never hear the end of it if I tell them no to any fun stuff.

Unfortunately most people do not see a thrown blade coming until it actually happens, my brother threw one on a Johnson Stinger cruising along about 2/3 power and hit something, got the power off, raised the engine saw the damage, did not have a spare prop and limped home at a tad above idle so it would not shake much,. lucky for him he was only a mile or two from his docking ramp when it happened.

After I retired I worked part time at a West Marine for a couple years and you will not believe the condition of props that were brought in for repairs. Many were unrepairable even stainless props came in all busted up.
 
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Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,030
Mike, Those telltales should be strong at all speeds, but they do clog easily. Pull the hose off the block and see if it is stronger. If not, I would expect an overheating potential for you. Did you old impeller come out intact, or could a piece of it gotten onto the motor?

Bill, You are a hard guy to help, so I will give up.
.
 

mlbinseattle

Petty Officer 2nd Class
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Aug 1, 2015
Messages
100
Mike, Those telltales should be strong at all speeds, but they do clog easily. Pull the hose off the block and see if it is stronger. If not, I would expect an overheating potential for you. Did you old impeller come out intact, or could a piece of it gotten onto the motor?

Bill, You are a hard guy to help, so I will give up.

I took the boat with me on this camping trip. (Returned today.) I checked for any blockages before leaving, and there weren't any. When I replaced the old impeller, it was ate up, and I dug out a several bits and pieces when I had the exhaust cover and inner/outer water jacket covers off. I also blew out all the passages with compressed air. I checked for any blockages, again, before leaving on the camping trip, and there weren't any. I'm confident there aren't any blockages, but I shall check one more time.

The other thing, the engine is not overheating. In fact, it's running pretty cool. I mean, the telltale is warm, but not scalding, and you can actually lay hands on the engine after running it without getting burnt. Ran it for several days while on the camping trip, and it performed great.

I'm thinking something happened to the new impeller. I'm going on another camping trip at the end of next week, and I'm going to pull the lower unit today or tomorrow to inspect the pump/impeller. I'll report back and let everyone know what I found.
 

Chris1956

Supreme Mariner
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Mar 25, 2004
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Mike, Remember that motor has no thermostat. It should run dead cold at idle and warmer at cruise. The key is that the impeller pumps enough water to cool the motor, at whatever load you have on it. So I would suggest you run it at idle and verify the motor is lake temp. Next cruise as normal and see that she is not too hot to touch for a few seconds.

BTW - never reuse an impeller, and never turn one over, and reinstall. It will fail.
 
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