More Speed?

H

howle

Cadet
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Jul 23, 2005
Messages
14
I am new to the outdrive world and I have many questions. I<br />I purchased a 1989 Mach 1 Concorde 23ft with th 260MR apha 1. The motor has 320 hrs and runs great so far. I do not know if regular maintenance was kept up. It will do approx 50 with my wife and I. It has a quicksilver 19p prop on it currently. I have no idea what the engine RPMs are since the tach is broke. <br /><br />My questions are: <br /><br />What type of maintenance should I have done?<br />What can I do to increase the speed.<br />Is this a good setup?<br />What should I look for as far as maintenance etc...<br /><br />Any comments/esperiance would greatly be appreciated.
 
N

novicetech

Petty Officer 1st Class
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Jan 19, 2004
Messages
267
Re: More Speed?

You really need to get the tach fixed, there are some pretty good prop experts on this forum but they will need to know what your wide open throttle rpms are.
 
H

howle

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Jul 23, 2005
Messages
14
Re: More Speed?

For this type of engine, what is the max rpm and can you run it at that range continuously
 
T

TilliamWe

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6,579
Re: More Speed?

Those ole 260s had an WOT rpm range of 4200-4600 I think. Certainly no higher than 4800.<br />Get the tach fixed, pronto. It's my opinion that you should be able to turn a 21p prop, so I am guessing that the 19 is over revving. A 21p would also give you more top end speed, if it can turn it to the proper WOT rpm.<br />They can run a long time at WOT. Great engine. Good low end torque. We had one in a 19' Renken in 1984, and it was a beast! Never broke the drive either.<br />Change the oil regularly, and change the drive gear lube as recommended. Also have the impeller in the drive replaced, if you have no record of when it was done last.
 
H

howle

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Jul 23, 2005
Messages
14
Re: More Speed?

Thanks guys. This has been really helpful. This weekend I remove the lower unit because I thought the gimble bearing was bad. I removed it and it was good along with the U-joint. I started the engine with the outdrive removed and it still makes a "clunking" sound. Any ideas?<br /><br />Additionall I repaired the tach. Due to the outdrive noise I have not had a chance to check the rpm etc..
 
Bondo

Bondo

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Re: More Speed?

I started the engine with the outdrive removed and it still makes a "clunking" sound. Any ideas?<br />
Click to expand...
When,...... Where,.........<br /><br />Explain........
 
H

howle

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Jul 23, 2005
Messages
14
Re: More Speed?

At idle, not a consistent noise.<br /><br />I pulled the flywheel access cover tonight and it still made the noise.<br /><br />It is consistent when letting off the throttle or giving it gas. Only thing I know to do now is pull the engine unless another idea comes up.<br /><br />It is not coming from a main bearing, it sounds like it may be from the transom but I know when noises travel through metal it could be from anywhere.
 
C

cslaufer

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Jul 5, 2005
Messages
25
Re: More Speed?

You may have flappers in the exhaust making the noise. Thant My 5 cents
 
W

WSUDERMAN

Petty Officer 2nd Class
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Sep 9, 2001
Messages
176
Re: More Speed?

You could try the rod to the ear trick to narrow down the location. Take a metal rod and place against different parts of the engine. Each time hold your hand over the end of the rod and put your ear against your hand on the end of the rod. This has the affect of amplifing and isolating the noise so you can find a focal point. This is one of those Grandpa Tricks...
 
H

howle

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Jul 23, 2005
Messages
14
Re: More Speed?

You fellas are awesome. I did try the stick method and it did not work for me. When I use to work in a garage we did it all the time though. <br /><br />Anyways I had a friend stop by just to get another set of eyes and ears on it and guess what it was. The darn bellows in the exhaust. I removed both cause they were wearing the inside tubes. I may replace them this winter but what I have heard is you really don’t need them? <br /><br />Additionally I have inspected all the bellows and found the shift cable busted. I figure why it is apart I will replace it. I had an estimate and they told me 250 + parts. I took the old one out and have decided to put it back together myself. With the manual, I should be able to do it. <br /><br />Thanks again guys, I have learned so much. Really impressed with this forum!!
 
R

rickf1985

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Jun 5, 2005
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Re: More Speed?

I will bet when you see that tach it is going to scare you. I have a 24' Baja with a 7.4, Bravo I running a 23 pitch bravo s/s prop and I amd turning 50 at 4100 rpm with a top speed of 65 at 4800. I think just about all the V-8's of that era had 1.50 ratios which means your 260 is screaming at 50 with a 19. Let us know what you find.<br />Rick
 
achris

achris

More fish than mountain goat
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May 19, 2004
Messages
27,468
Re: More Speed?

I've just put the numbers in my prop calculator and with the following information.<br /><br />Speed : 50mph<br />Ratio : 1.5:1<br />Prop : 14" x 19"<br /><br />You should be running around the 4600-4800 rpm mark.<br /><br />Chris..........
 
Bondo

Bondo

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Re: More Speed?

Originally posted by achris:<br /> I've just put the numbers in my prop calculator and with the following information.<br /><br />Speed : 50mph<br />Ratio : 1.5:1<br />Prop : 14" x 19"<br /><br />You should be running around the 4600-4800 rpm mark.<br /><br />Chris..........
Click to expand...
Ayuh,..............<br /><br />That's Not Too Bad at All,..........<br /><br />But,.... Fixing the Tach is No Doubt,... Priority 1.............. ;)
 
H

howle

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Jul 23, 2005
Messages
14
Re: More Speed?

Well I have learned much during the past few weeks. <br /><br />I have changed the gimble bearing, u joints, shift boot, and removed the flappers out of the exhaust that was causing the funny noise. Additionally I have changed the tach and it reads great.<br /><br />Here is my info.<br /><br />1.5 gear ratio<br />260 Mercruiser (350) alpha drive<br />4600 rpm 50mph with 19 pitch prop.<br /><br />The boat is 23ft long. <br /><br />I have heard I could make the mid 50s with a 22pitch prop. Is this correct?
 
Don S

Don S

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Aug 31, 2004
Messages
62,321
Re: More Speed?

I have heard I could make the mid 50s with a 22pitch prop. Is this correct?
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Probably not. Speed has a lot to do with hull design, and you are at the perfect WOT rpm. lowering it will overload the engine, causing it to wear out faster, and probably only gain you MAYBE 1 or 2 mph.<br />You need a BIG increase in horse power to gain 10 mph.
 
H

howle

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Joined
Jul 23, 2005
Messages
14
Re: More Speed?

One more question.<br /><br />Can you run the boat at 4600-4800 rpms?
 
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